Table of Contents

Multiple Indicator Cluster Survey (MICS)

Statistics and Monitoring
Four surfaces of incisors and canines and five surfaces, including the occlusal surface, of premolars and molars were examined. US Department of Agriculture; Children can play in the rain and snow and in low temperatures when wearing clothing that keeps them dry and warm. Findings also suggest that Mexican-Americans continue to have the lowest prevalence of edentulism, although non-Hispanic whites also have experienced a decline in edentulism since In order to appropriately safeguard the information in them, as described above, these cookies are encrypted.

Work Environment

National Oceanic and Atmospheric Administration

Because the coordinated design enabled estimates to be developed by State in all 50 States plus the District of Columbia, States may be viewed as the first level of stratification and as a variable for reporting estimates. In , the actual sample sizes in these States ranged from 3, to 3, For the remaining 42 States and the District of Columbia, the target sample size was Sample sizes in these States ranged from to in This approach ensured there was sufficient sample in every State to support State estimation by either direct methods or small area estimation SAE 9 while at the same time providing adequate precision for national estimates.

These regions were contiguous geographic areas designed to yield approximately the same number of interviews. Within each SSR, 48 census tracts were selected with probability proportional to population size. One area segment was selected within each sampled census tract with probability proportional to population size. Eight reserve sample segments per SSR were fielded during the survey year.

Four of these segments were retained from the survey, and four were selected for use in the survey. These sampled segments were allocated equally into four separate samples, one for each 3-month period calendar quarter during the year. That is, a sample of addresses was selected from two segments in each calendar quarter so that the survey was relatively continuous in the field.

In each of the area segments, a listing of all addresses was made, from which a national sample of , addresses was selected. Of the selected addresses, , were determined to be eligible sample units. In these sample units which can be either households or units within group quarters , sample persons were randomly selected using an automated screening procedure programmed in a handheld computer carried by the interviewers.

The number of sample units completing the screening was , Youths aged 12 to 17 years and young adults aged 18 to 25 years were oversampled at this stage, with 12 to 17 year olds sampled at an actual rate of Similarly, persons in age groups 26 or older were sampled at rates of The overall population sampling rates were 0.

Nationwide, 88, persons were selected. In addition, State samples were representative of their respective State populations. The data collection method used in NSDUH involves in-person interviews with sample persons, incorporating procedures to increase respondents' cooperation and willingness to report honestly about their illicit drug use behavior.

Confidentiality is stressed in all written and oral communications with potential respondents. Respondents' names are not collected with the data, and computer-assisted interviewing CAI methods are used to provide a private and confidential setting to complete the interview. Introductory letters are sent to sampled addresses, followed by an interviewer visit. The computer uses the demographic data in a preprogrammed selection algorithm to select zero to two sample persons, depending on the composition of the household.

This selection process is designed to provide the necessary sample sizes for the specified population age groupings. All interviewers carry copies of this letter in Spanish.

If the interviewer is not certified bilingual, he or she will use preprinted Spanish cards to attempt to find someone in the household who speaks English and who can serve as the screening respondent or who can translate for the screening respondent. In households where a language other than Spanish is encountered, another language card is used to attempt to find someone who speaks English to complete the screening.

If the sample person prefers to complete the interview in Spanish, a certified bilingual interviewer is sent to the address to conduct the interview. Immediately after the completion of the screener, interviewers attempt to conduct the NSDUH interview with each sample person in the household. The interviewer requests that the sampled respondent identify a private area in the home to conduct the interview away from other household members. The interview averages about an hour and includes a combination of CAPI computer-assisted personal interviewing, in which the interviewer reads the questions and ACASI audio computer-assisted self-interviewing.

The core consists of initial demographic items which are interviewer-administered and self-administered questions pertaining to the use of tobacco, alcohol, marijuana, cocaine, crack cocaine, heroin, hallucinogens, inhalants, pain relievers, tranquilizers, stimulants, and sedatives. Topics in the remaining noncore self-administered sections include but are not limited to injection drug use, perceived risks of substance use, substance dependence or abuse, arrests, treatment for substance use problems, pregnancy and health care issues, and mental health issues.

Noncore demographic questions which are interviewer-administered and follow the ACASI questions address such topics as immigration, current school enrollment, employment and workplace issues, health insurance coverage, and income.

Thus, the interview begins in CAPI mode with the FI reading the questions from the computer screen and entering the respondent's replies into the computer. No personal identifying information about the respondent is captured in the CAI record. Screening and interview data are encrypted while they reside on laptops and mobile computers. Data are transmitted back to RTI on a regular basis using either a direct dial-up connection or the Internet. All data are encrypted while in transit across dial-up or Internet connections.

After the data are transmitted to RTI, certain cases are selected for verification. For completed interviews, respondents write their home telephone number and mailing address on a quality control form and seal the form in a preaddressed envelope that FIs mail back to RTI.

All contact information is kept completely separate from the answers provided during the screening or interview. Samples of respondents who completed screenings or interviews are randomly selected for verification. These cases are called by telephone interviewers who ask scripted questions designed to determine the accuracy and quality of the data collected. Any cases discovered to have a problem or discrepancy are flagged and routed to a small specialized team of telephone interviewers who recontact respondents for further investigation of the issue s.

Depending on the amount of an FI's work that cannot be verified through telephone verification, including bad telephone numbers e. Field verification involves another FI returning to the sampled DU to verify the accuracy and quality of the data in person. If the verification procedures identify situations in which an FI has falsified data, the FI is terminated. All cases completed that quarter by the falsifying FI are verified and reworked by the FI conducting the field verification.

Any cases completed by the falsifying FI in earlier quarters of the same year are also verified. All cases from earlier quarters identified as falsified or unresolvable are removed and not reworked. Examples of unresolvable cases include those for which verifiers were never able to make contact with a resident of the DU, residents who refused to verify their data, previous residents who had moved, or residents who reported accurate roster data for the DU but did not recall speaking to an FI.

Data that FIs transmit to RTI are processed to create a raw data file in which no logical editing of the data has been done. The raw data file consists of one record for each transmitted interview. Cases are eligible to be treated as final respondents only if they provided data on lifetime use of cigarettes and at least 9 out of 13 of the other substances in the core section of the questionnaire.

Even though editing and consistency checks are done by the CAI program during the interview, additional, more complex edits and consistency checks are completed at RTI. Additionally, statistical imputation is used to replace missing or ambiguous values after editing for some key variables.

Analysis weights are created so that estimates will be representative of the target population. Details of the editing, imputation, and weighting procedures for will appear in the NSDUH Methodological Resource Book , which is in process. With the exception of industry and occupation data, coding of written answers that respondents or interviewers typed was performed at RTI for the NSDUH. Written responses in "OTHER, Specify" data were assigned numeric codes through computer-assisted survey procedures and the use of a secure Web site that allowed for coding and review of the data.

The computer-assisted procedures entailed a database check for a given "OTHER, Specify" variable that contained typed entries and the associated numeric codes. If an exact match was found between the typed response and an entry in the system, the computer-assisted procedures assigned the appropriate numeric code.

Typed responses that did not match an existing entry were coded through the Web-based coding system. Data on the industries in which respondents worked and respondents' occupations were assigned numeric industry and occupation codes by staff at the U. As noted above, the CAI program included checks that alerted respondents or interviewers when an entered answer was inconsistent with a previous answer in a given module.

In this way, the inconsistency could be resolved while the interview was in progress. However, not every inconsistency was resolved during the interview, and the CAI program did not include checks for every possible inconsistency that might have occurred in the data. For example, if respondents reported that they never used a given drug, the CAI logic skipped them out of all remaining questions about use of that drug.

Similarly, respondents were instructed in the prescription psychotherapeutics modules i. Therefore, if a respondent's only report of lifetime use of a particular type of "prescription" psychotherapeutic drug was for an OTC drug, the respondent was logically inferred never to have been a nonmedical user of the prescription drugs in that psychotherapeutic category.

In addition, respondents could report that they were lifetime users of a drug but not provide specific information on when they last used it. In this situation, a temporary "indefinite" value for the most recent period of use was assigned to the edited recency-of-use variable e. The editing procedures for key drug use variables also involved identifying inconsistencies between related variables so that these inconsistencies could be resolved through statistical imputation.

In this example, the inconsistent period of most recent use was replaced with an "indefinite" value, and the inconsistent age at first use was replaced with a missing data code.

These indefinite or missing values were subsequently imputed through statistical procedures to yield consistent data for the related measures, as discussed in the next section.

For some key variables that still had missing or ambiguous values after editing, statistical imputation was used to replace these values with appropriate response codes. In this case, the imputation procedure assigns a value for when the respondent last used the drug e. Similarly, if a response is completely missing, the imputation procedures replace missing values with nonmissing ones. PMN allows for the following: The PMN method has some similarity with the predictive mean matching method of Rubin except that, for the donor records, Rubin used the observed variable value not the predictive mean to compute the distance function.

Also, the well-known method of nearest neighbor imputation is similar to PMN, except that the distance function is in terms of the original predictor variables and often requires somewhat arbitrary scaling of discrete variables.

PMN is a combination of a model-assisted imputation methodology and a random nearest neighbor hot-deck procedure. The hot-deck procedure within the PMN method ensures that missing values are imputed to be consistent with nonmissing values for other variables. Whenever feasible, the imputation of variables using PMN is multivariate, in which imputation is accomplished on several response variables at once.

In the modeling stage of PMN, the model chosen depends on the nature of the response variable. In the NSDUH, the models included binomial logistic regression, multinomial logistic regression, Poisson regression, time-to-event survival regression, and ordinary linear regression, where the models incorporated the sampling design weights. In general, hot-deck imputation replaces an item nonresponse missing or ambiguous value with a recorded response that is donated from a "similar" respondent who has nonmissing data.

For random nearest neighbor hot-deck imputation, the missing or ambiguous value is replaced by a responding value from a donor randomly selected from a set of potential donors. Potential donors are those defined to be "close" to the unit with the missing or ambiguous value according to a predefined function called a distance metric.

In the hot-deck procedure of PMN, the set of candidate donors the "neighborhood" consists of respondents with complete data who have a predicted mean close to that of the item nonrespondent. The predicted means are computed both for respondents with and without missing data, which differs from Rubin's method where predicted means are not computed for the donor respondent Rubin, In the univariate case where only one variable is imputed using PMN , the neighborhood of potential donors is determined by calculating the relative distance between the predicted mean for an item nonrespondent and the predicted mean for each potential donor, then choosing those means defined by the distance metric.

The pool of donors is restricted further to satisfy logical constraints whenever necessary e. Whenever possible, missing or ambiguous values for more than one response variable are considered together. In this multivariate case, the distance metric is a Mahalanobis distance, which takes into account the correlation between variables Manly, , rather than a Euclidean distance.

The Euclidean distance is the square root of the sum of squared differences between each element of the predictive mean vector for the respondent and the predictive mean vector for the nonrespondent.

The Mahalanobis distance standardizes the Euclidean distance by the variance-covariance matrix, which is appropriate for random variables that are correlated or have heterogeneous variances.

Whether the imputation is univariate or multivariate, only missing or ambiguous values are replaced, and donors are restricted to be logically consistent with the response variables that are not missing. Furthermore, donors are restricted to satisfy "likeness constraints" whenever possible. That is, donors are required to have the same values for variables highly correlated with the response. For example, donors for the age at first use variable are required to be of the same age as recipients, if at all possible.

If no donors are available who meet these conditions, these likeness constraints can be loosened. Although statistical imputation could not proceed separately within each State due to insufficient pools of donors, information about each respondent's State of residence was incorporated in the modeling and hot-deck steps. For most drugs, respondents were separated into three "State usage" categories as follows: This categorical "State rank" variable was used as one set of covariates in the imputation models.

In addition, eligible donors for each item nonrespondent were restricted to be of the same State usage category i. Variables for measures that are highly sensitive or that may not be known to younger respondents e. In addition, certain variables that are subject to a greater number of skip patterns and consistency checks e. The general approach to developing and calibrating analysis weights involved developing design-based weights as the product of the inverse of the selection probabilities at each selection stage.

Since , NSDUH has used a four-stage sample selection scheme in which an extra selection stage of census tracts was added before the selection of a segment. Thus, the design-based weights, , incorporate an extra layer of sampling selection to reflect the sample design change. Adjustment factors, , then were applied to the design-based weights to adjust for nonresponse, to poststratify to known population control totals, and to control for extreme weights when necessary.

In view of the importance of State-level estimates with the State design, it was necessary to control for a much larger number of known population totals.

Several other modifications to the general weight adjustment strategy that had been used in past surveys also were implemented for the first time beginning with the CAI sample. Weight adjustments were based on a generalization of Deville and Särndal's logit model. The final weights minimize the distance function defined as. Every effort was made to include as many relevant State-specific covariates typically defined by demographic domains within States as possible in the multivariate models used to calibrate the weights nonresponse adjustment and poststratification steps.

Because further subdivision of State samples by demographic covariates often produced small cell sample sizes, it was not possible to retain all State-specific covariates even after meaningful collapsing of covariate categories and still estimate the necessary model parameters with reasonable precision.

Therefore, a hierarchical structure was used in grouping States with covariates defined at the national level, at the census division level within the Nation, at the State group within the census division, and, whenever possible, at the State level. Census Bureau has produced the necessary population estimates for the same year as each NSDUH survey in response to a special request.

This shift to the census data for the NSDUH could have affected comparisons between substance use estimates in and onward and those from prior years. Consistent with the surveys from onward, control of extreme weights through separate bounds for adjustment factors was incorporated into the GEM calibration processes for both nonresponse and poststratification.

This is unlike the traditional method of winsorization in which extreme weights are truncated at prespecified levels and the trimmed portions of weights are distributed to the nontruncated cases. In GEM, it is possible to set bounds around the prespecified levels for extreme weights. Then the calibration process provides an objective way of deciding the extent of adjustment or truncation within the specified bounds.

A step was included to poststratify the household-level weights to obtain census-consistent estimates based on the household rosters from all screened households.

An additional step poststratified the selected person sample to conform to the adjusted roster estimates. The respondent poststratification step poststratified the respondent person sample to external census data defined within the State whenever possible, as discussed above.

The person-level weights for estimates based on the annual averages were obtained by dividing the analysis weights for the 2 specific years by a factor of 2. The estimates of drug use prevalence from the National Survey on Drug Use and Health NSDUH are designed to describe the target population of the survey—the civilian, noninstitutionalized population aged 12 or older living in the United States.

However, it excludes some small subpopulations that may have very different drug use patterns. For example, the survey excludes active military personnel, who have been shown to have significantly lower rates of illicit drug use. The survey also excludes two groups that have been shown to have higher rates of illicit drug use: Readers are reminded to consider the exclusion of these subpopulations when interpreting results.

This report includes national estimates that were drawn from a set of tables referred to as "detailed tables" that are available at http: The final, nonresponse-adjusted, and poststratified analysis weights were used in SUDAAN to compute unbiased design-based drug use estimates. The sampling error of an estimate is the error caused by the selection of a sample instead of conducting a census of the population.

The use of probability sampling methods in NSDUH allows estimation of sampling error from the survey data. The SEs are used to identify unreliable estimates and to test for the statistical significance of differences between estimates.

Estimates of means or proportions, , such as drug use prevalence estimates for a domain d , can be expressed as a ratio estimate:. When the domain size, , is free of sampling error, an estimate of the SE for the total number of substance users is. This approach is theoretically correct when the domain size estimates, , are among those forced to match their respective U. Census Bureau population estimates through the weight calibration process.

In addition, more detailed information about the weighting procedures for will appear in the NSDUH Methodological Resource Book , which is in process.

For estimated domain totals, , where is not fixed i. Census Bureau population estimates , this formulation still may provide a good approximation if it can be assumed that the sampling variation in is negligible relative to the sampling variation in. This is a reasonable assumption for many cases in this study.

For some subsets of domain estimates, the above approach can yield an underestimate of the SE of the total when was subject to considerable variation. Because of this underestimation, alternatives for estimating SEs of totals were implemented. Since the NSDUH report, a "mixed" method approach has been implemented for all detailed tables to improve the accuracy of SEs and to better reflect the effects of poststratification on the variance of total estimates.

This approach assigns the methods of SE calculation to domains i. The set of domains considered controlled i. Domains consisting of three-way interactions may be controlled in a single year but not necessarily in preceding or subsequent years.

As a result of the use of this mixed-method approach, the SEs for the total estimates within many detailed tables were calculated differently from those in NSDUH reports prior to the report.

However, the list does include all of the domains that were used in computing SEs for estimates produced in this report and in the detailed tables. This table includes both the main effects and two-way interactions and may be used to identify the method of SE calculation employed for estimates of totals. Estimates among the total population age main effect , males and females age by gender interaction , and Hispanics and non-Hispanics age by Hispanic origin interaction were treated as controlled in this table, and the formula above was used to calculate the SEs.

Estimates presented in this report for racial groups are for non-Hispanics. However, published estimates for whites by age group in this report and in the detailed tables actually represent a three-way interaction: The criteria used to define unreliability of direct estimates from NSDUH are based on the prevalence for proportion estimates , relative standard error RSE defined as the ratio of the SE over the estimate , nominal actual sample size, and effective sample size for each estimate.

Proportion estimates , or rates, within the range [ ], and the corresponding estimated numbers of users were suppressed if. Using a first-order Taylor series approximation to estimate and , the following equation was derived and used for computational purposes when applying a suppression rule dependent on effective sample size:.

Using the minimum effective sample size for the suppression rule would mean that estimates of between. To simplify requirements and maintain a conservative suppression rule, estimates of between. Beginning with the survey, the suppression rule for proportions based on described previously replaced a rule in which data were suppressed whenever. This rule was changed because the rule prior to imposed a very stringent application for suppressing estimates when is small but imposed a very lax application for large.

The new rule ensured a more uniformly stringent application across the whole range of i. The previous rule also was asymmetric in the sense that suppression only occurred in terms of. That is, there was no complementary rule for , which the current NSDUH suppression criteria for proportions take into account. Estimates of totals were suppressed if the corresponding prevalence rates were suppressed. Estimates of means that are not bounded between 0 and 1 e.

This rule was based on an empirical examination of the estimates of mean age of first use and their SEs for various empirical sample sizes.

Although arbitrary, a sample size of 10 appeared to provide sufficient precision and still allow reporting by year of first use for many substances. This section describes the methods used to compare prevalence estimates in this report. Customarily, the observed difference between estimates is evaluated in terms of its statistical significance. Statistical significance is based on the p value of the test statistic and refers to the probability that a difference as large as that observed would occur because of random variability in the estimates if there were no difference in the prevalence estimates for the population groups being compared.

The significance of observed differences in this report is reported at the. When comparing prevalence estimates, the null hypothesis no difference between prevalence estimates was tested against the alternative hypothesis there is a difference in prevalence estimates using the standard difference in proportions test expressed as.

In cases where significance tests between years were performed, the prevalence estimate from the earlier year becomes the first estimate, and the prevalence estimate from the later year becomes the second estimate e. Under the null hypothesis, Z is asymptotically distributed as a standard normal random variable.

Therefore, calculated values of Z can be referred to the unit normal distribution to determine the corresponding probability level i. A similar procedure and formula for Z were used for estimated totals. When comparing population subgroups across three or more levels of a categorical variable, log-linear chi-square tests of independence of the subgroups and the prevalence variables were conducted using SUDAAN in order to first control the error level for multiple comparisons.

If Shah's Wald F test transformed from the standard Wald chi-square indicated overall significant differences, the significance of each particular pairwise comparison of interest was tested using SUDAAN analytic procedures to properly account for the sample design RTI International, Using the published estimates and SEs to perform independent t tests for the difference of proportions usually will provide the same results as tests performed in SUDAAN.

However, where the significance level is borderline, results may differ for two reasons: A caution in interpreting trends in totals e. The estimate for was determined to be affected by large analysis weights for a small number of heroin users and suggests that the estimated numbers of past year and past month heroin users in were statistical anomalies. This finding also underscores the importance of reviewing trends across a larger range of years especially for outcome measures that correspond to a relatively small proportion of the total population e.

The analyses focused on prevalence estimates for 8th and 10th graders and prevalence estimates for young adults aged 19 to 24 for through Estimates for the 8th and 10th grade students were calculated using MTF data as the simple average of the 8th and 10th grade estimates.

Estimates for young adults aged 19 to 24 were calculated using MTF data as the simple average of three modal age groups: Published results were not available from NIDA for significant differences in prevalence estimates between years for these subgroups, so testing was performed using information that was available. For the 8th and 10th grade average estimates, tests of differences were performed between and the 11 prior years.

Estimates for persons in grade 8 and grade 10 were considered independent, simplifying the calculation of variances for the combined grades. Across years, the estimates for involved samples independent of those in to Design effects published in Johnston et al. For the to year-old age group, tests of differences were done assuming independent samples between years an odd number of years apart because two distinct cohorts a year apart were monitored longitudinally at 2-year intervals.

This is appropriate for comparisons of , , , , , and data with data. However, this assumption results in conservative tests for comparisons of , , , , and data with data because testing did not take into account covariances associated with repeated observations from the longitudinal samples. Estimates of covariances were not available. This discussion also includes variance estimation in the MTF data for testing between adjacent survey years.

The accuracy of survey estimates can be affected by nonresponse, coding errors, computer processing errors, errors in the sampling frame, reporting errors, and other errors not due to sampling. These types of "nonsampling errors" and their impact are reduced through data editing, statistical adjustments for nonresponse, close monitoring and periodic retraining of interviewers, and improvement in quality control procedures.

Although these types of errors often can be much larger than sampling errors, measurement of most of these errors is difficult. However, some indication of the effects of some types of these errors can be obtained through proxy measures, such as response rates, and from other research studies. Of the , eligible households sampled for the NSDUH, , were screened successfully, for a weighted screening response rate of To be considered a completed interview, a respondent must provide enough data to pass the usable case rule.

A total of 15, sample persons Among demographic subgroups, the weighted IRR was higher among 12 to 17 year olds The overall weighted response rate, defined as the product of the weighted screening response rate and weighted interview response rate or. Nonresponse bias can be expressed as the product of the nonresponse rate and the difference between the characteristic of interest between respondents and nonrespondents in the population.

By maximizing NSDUH response rates, it is hoped that the bias due to the difference between the estimates from respondents and nonrespondents is minimized. Drug use surveys are particularly vulnerable to nonresponse because of the difficult nature of accessing heavy drug users. However, in a study that matched census data to NHSDA nonrespondents, 15 it was found that populations with low response rates did not always have high drug use rates. For example, although some populations were found to have low response rates and high drug use rates e.

Among survey participants, item response rates were generally very high for most drug use items. However, respondents could give inconclusive or inconsistent information about whether they ever used a given drug i. In addition, respondents could give inconsistent responses to items such as when they first used a drug compared with their most recent use of a drug. These missing or inconsistent responses first are resolved where possible through a logical editing process.

Additionally, missing or inconsistent responses are imputed using statistical methodology. These imputation procedures in NSDUH are based on responses to multiple questions, so that the maximum amount of information is used in determining whether a respondent is classified as a user or nonuser, and if the respondent is classified as a user, whether the respondent is classified as having used in the past year or the past month.

For example, ambiguous data on the most recent use of cocaine are statistically imputed based on a respondent's data for use or most recent use of tobacco products, alcohol, inhalants, marijuana, hallucinogens, and nonmedical use of prescription psychotherapeutic drugs. Nevertheless, editing and imputation of missing responses are potential sources of measurement error. The reliability of the responses was assessed by comparing the responses of the first interview with the responses from the reinterview.

This section summarizes the results for the reliability of selected variables related to substance use and demographic characteristics. The kappa values for the lifetime and past year substance use variables marijuana use, alcohol use, and cigarette use all showed almost perfect response consistency, ranging from 0. The value obtained for the substance dependence or abuse measure in the past year showed substantial agreement 0.

The variables for age at first use of marijuana and perceived great risk of smoking marijuana once a month showed substantial agreement 0. The demographic variables showed almost perfect agreement, ranging from 0.

For further information on the reliability of a wide range of measures contained in NSDUH, see the complete methodology report Chromy et al. Most substance use prevalence estimates, including those produced for NSDUH, are based on self-reports of use. Although studies generally have supported the validity of self-report data, it is well documented that these data may be biased underreported or overreported.

The bias varies by several factors, including the mode of administration, the setting, the population under investigation, and the type of drug Aquilino, ; Brener et al.

NSDUH utilizes widely accepted methodological practices for increasing the accuracy of self-reports, such as encouraging privacy through audio computer-assisted self-interviewing ACASI and providing assurances that individual responses will remain confidential. Various procedures have been used to validate self-report data, such as biological specimens e. However, these procedures often are impractical or too costly for general population epidemiological studies SRNT Subcommittee on Biochemical Verification, However, there were some reporting differences in either direction, with some respondents not reporting use but testing positive, and some reporting use but testing negative.

Technical and statistical problems related to the hair tests precluded presenting comparisons of self-reports and hair test results, while small sample sizes for self-reports and positive urine test results for opiates and stimulants precluded drawing conclusions about the validity of self-reports of these drugs. Further, inexactness in the window of detection for drugs in biological specimens and biological factors affecting the window of detection could account for some inconsistency between self-reports and urine test results.

These errors resulted from fraudulent cases submitted by field interviewers and affected the data for Pennsylvania to and Maryland and Although all fraudulent interview cases were removed from the data files, the affected screening cases were not removed because they were part of the assigned sample. Instead, these screening cases were assigned a final screening code of 39 "Fraudulent Case" and treated as incomplete with unknown eligibility.

The screening eligibility status for these cases then was imputed. The cases that were imputed to be ineligible did not contribute to the weights and were reported as "Other, Ineligible" in the affected years.

However, some estimates for to in the national findings report and the detailed tables, as well as other new reports, may differ from corresponding estimates found in some previous reports or tables. These errors had minimal impact on the national estimates and no effect on direct estimates for the other 48 States and the District of Columbia. In reports where model-based small area estimation techniques are used, estimates for all States may be affected, even though the errors were concentrated in only two States.

In reports that do not use model-based estimates, the only estimates appreciably affected are estimates for Pennsylvania, Maryland, the mid-Atlantic division, and the Northeast region. The national findings report and detailed tables do not include State-level or model-based estimates. However, they do include estimates for the mid-Atlantic division and the Northeast region. Single-year estimates based on to data and estimates based on pooled data including any of these years may differ from previously published estimates.

Tables and estimates based only on data since are unaffected by these data errors. Caution is advised when comparing data from older reports with data from more recent reports that are based on corrected data files. As discussed previously, comparisons of estimates for Pennsylvania, Maryland, the mid-Atlantic division, and the Northeast region are of most concern, while comparisons of national data or data for other States and regions are essentially still valid.

In particular, CBHSQ has released a set of modified detailed tables that include revised to estimates for the mid-Atlantic division and the Northeast region for certain key measures.

CBHSQ does not recommend making comparisons between unrevised to estimates and estimates based on data for and subsequent years for the geographic areas of greatest concern. In epidemiological studies, incidence is defined as the number of new cases of a disease occurring within a specific period of time. Similarly, in substance use studies, incidence refers to the first use of a particular substance.

This measure is determined by self-reported past year use, age at first use, year and month of recent new use, and the interview date.

Since , the survey questionnaire has allowed for collection of year and month of first use for recent initiates i. Month, day, and year of birth also are obtained directly or are imputed for item nonrespondents as part of the data postprocessing.

Additionally, the computer-assisted interviewing CAI instrument records and provides the date of the interview. By imputing a day of first use within the year and month of first use, a specific date of first use can be used for estimation purposes. Past year initiation among persons using a substance in the past year can be viewed as an indicator variable defined as follows:. The total number of past year initiates can be used in the estimation of different percentages.

The detailed tables show all three of these percentages. Calculation of estimates of past year initiation do not take into account whether a respondent initiated substance use while a resident of the United States. This method of calculation allows for direct comparability with other standard measures of substance use because the populations of interest for the measures will be the same i. One important note for incidence estimates is the relationship between main categories and subcategories of substances e.

For most measures of substance use, any member of a subcategory is by necessity a member of the main category e. However, this is not the case with regard to incidence statistics. Because an individual can only be an initiate of a particular substance category main or sub a single time, a respondent with lifetime use of multiple substances may not, by necessity, be included as a past year initiate of a main category, even if he or she were a past year initiate for a particular subcategory because his or her first initiation of other substances within the main category could have occurred earlier.

In addition to estimates of the number of persons initiating use of a substance in the past year, estimates of the mean age of past year initiates of these substances are computed.

Unless specified otherwise, estimates of the mean age at initiation in the past 12 months have been restricted to persons aged 12 to 49 so that the mean age estimates reported are not influenced by those few respondents who were past year initiates and were aged 50 or older.

As a measure of central tendency, means are influenced heavily by the presence of extreme values in the data, and this constraint should increase the utility of these results to health researchers and analysts by providing a better picture of the substance use initiation behaviors among the civilian, noninstitutionalized population in the United States. This constraint was applied only to estimates of mean age at first use and does not affect estimates of the numbers of new users or the incidence rates.

Although past year initiates aged 26 to 49 are assumed not to be as likely as past year initiates aged 50 or older to influence mean ages at first use, caution still is advised in interpreting trends in these means.

Consequently, review of substance initiation trends across a larger range of years is especially advised for this age group.

The estimated number of past year marijuana initiates aged 26 to 49 in was not significantly different from the numbers in to Except for , the estimated numbers of past year marijuana initiates in this age group since were not significantly different from the number in Since , only the mean age at first use of marijuana in The mean age at first use for any illicit drug among past year initiates aged 26 to 49 in Again, these findings indicate the importance of examining substance initiation trends across a larger range of years for this age group.

Except for the differences that were indicated, trends in the mean age at initiation for marijuana and any illicit drug among initiates aged 26 to 49 have been fairly stable since Similarly, the mean age at first use of inhalants among past year initiates aged 12 to 49 was higher in than in In comparison, the median ages at first use for inhalants, which are less susceptible to the influence of extreme values, were 18 years for past year initiates aged 12 to 49 in and 16 years for those in Thus, the higher mean in could be explained by the effect of extreme values on the age at first use in This finding also underscores the importance of reviewing mean ages at first use across a larger range of years.

Anomalous 1-year shifts in the mean age at first use typically "correct" themselves with 1 or 2 additional years of data. Because NSDUH is a survey of persons aged 12 years old or older at the time of the interview, younger individuals in the sample dwelling units are not eligible for selection into the NSDUH sample.

Some of these younger persons may have initiated substance use during the past year. As a result, past year initiate estimates suffer from undercoverage if a reader assumes that these estimates reflect all initial users instead of reflecting only those above the age of For earlier years, data can be obtained retrospectively based on the age at and date of first use.

As an example, persons who were 12 years old on the date of their interview in the survey may report having initiated use of cigarettes between 1 and 2 years ago; these persons would have been past year initiates reported in the survey had persons who were 11 years old on the date of the interview been allowed to participate in the survey.

Similarly, estimates of past year use by younger persons age 10 or younger can be derived from the current survey, but they apply to initiation in prior years and not the survey year. To get an impression of the potential undercoverage in the current year, reports of substance use initiation reported by persons aged 12 or older were estimated for the years in which these persons would have been 1 to 11 years younger.

These estimates do not necessarily reflect behavior by persons 1 to 11 years younger in the current survey. Instead, the data for the 11 year olds reflect initiation in the year prior to the current survey, the data for the 10 year olds reflect behavior between the 12th and 23rd months prior to this year's survey, and so on. A very rough way to adjust for the difference in the years that the estimate pertains to without considering changes in the population is to apply an adjustment factor to each age-based estimate of past year initiates.

This adjustment factor can be based on a ratio of lifetime users aged 12 to 17 in the current survey year to the same estimate for the prior applicable survey year.

To illustrate the calculation, consider past year use of alcohol. In the survey, , persons who were 12 years old were estimated to have initiated use of alcohol between 1 and 2 years earlier. These persons would have been past year initiates in the survey conducted on the same dates had the survey covered younger persons.

The estimated number of lifetime users currently aged 12 to 17 was 7,, for and 8,, for , indicating fewer overall initiates of alcohol use among persons aged 17 or younger in Thus, an adjusted estimate of initiation of alcohol use by persons who were 11 years old in is given by. This yielded an adjusted estimate of 96, persons 11 years old on a survey date and initiating use of alcohol in the past year:.

A similar procedure was used to adjust the estimated number of past year initiates among persons who would have been 10 years old on the date of the interview in and for younger persons in earlier years. The overall adjusted estimate for past year initiates of alcohol use by persons 11 years of age or younger on the date of the interview was ,, or about 3.

Based on similar analyses, the estimated undercoverage of past year initiates was 2. The undercoverage of past year initiates aged 11 or younger also affects the mean age at first use estimate. An adjusted estimate of the mean age at first use was calculated using a weighted estimate of the mean age at first use based on the current survey and the numbers of persons aged 11 or younger in the past year obtained in the aforementioned analysis for estimating undercoverage of past year initiates.

Analysis results showed that the mean age at first use was changed from The decreases reported above are comparable with results generated in prior survey years. Specifically, for marijuana, hallucinogens, inhalants, and tranquilizers, a respondent was defined as having dependence if he or she met three or more of the following six dependence criteria:. For alcohol, cocaine, heroin, pain relievers, sedatives, and stimulants, a seventh withdrawal criterion was added.

The seventh withdrawal criterion is defined by a respondent reporting having experienced a certain number of withdrawal symptoms that vary by substance e. A respondent was defined as having dependence if he or she met three or more of seven dependence criteria for these substances.

For each illicit drug and alcohol, a respondent was defined as having abused that substance if he or she met one or more of the following four abuse criteria and was determined not to be dependent on the respective substance in the past year:.

Criteria used to determine whether a respondent was asked about the dependence and abuse questions during the interview included the core substance use questions, the frequency of substance use questions for alcohol and marijuana only , and the noncore substance use questions for cocaine, heroin, and stimulants, including methamphetamine.

Missing or incomplete responses in the core substance use and frequency of substance use questions were imputed. However, the imputation process did not take into account reported data in the noncore i. Very infrequently, this may result in responses to the dependence and abuse questions that are inconsistent with the imputed substance use or frequency of substance use. For alcohol and marijuana, respondents were asked the dependence and abuse questions if they reported substance use on more than 5 days in the past year, or if they reported any substance use in the past year but did not report their frequency of past year use i.

These missing frequency data were subsequently imputed after data collection processing. Therefore, inconsistencies could have occurred where the imputed frequency of use response indicated less frequent use than required for respondents to be asked the dependence and abuse questions originally i. For alcohol, for example, about 40, respondents were past year alcohol users in Of these, fewer than respondents were missing their frequency data, but were still asked the alcohol dependence and abuse questions; however, their final imputed frequency of use indicated that they used alcohol on 5 or fewer days in the past year.

For cocaine, heroin, and stimulants, respondents were asked the dependence and abuse questions if they reported past year use in a core drug module or past year use in the noncore special drugs module. Thus, the CAI logic allowed some respondents to be asked the dependence and abuse questions for these drugs even if they did not report past year use in the corresponding core module.

For cocaine, for example, fewer than 1, respondents in were asked the questions about cocaine dependence and abuse because they reported past year use of cocaine or crack in the core section of the interview.

Fewer than 10 additional respondents were asked these questions because they reported past year use of cocaine with a needle in the special drugs module despite not having previously reported past year use of cocaine or crack. In , two new questions were added to the noncore special drugs module about past year methamphetamine use: Which answer is correct? Based on the decisions made during the methamphetamine analysis, 17 respondents who indicated past year methamphetamine use solely from these new special drug use questions i.

Furthermore, if these same respondents were categorized as not having past year dependence or abuse of any other psychotherapeutic drug e. Also, if these respondents were not classified as having dependence or abuse for other substances e.

In , questionnaire logic for determining hallucinogen, stimulant, and sedative dependence or abuse was modified. The revised skip logic used information collected in the noncore special drugs module in addition to that collected in questions from the core drug modules. Complying with the previous decision to exclude respondents whose methamphetamine use was based solely on responses to noncore questions from being classified as having stimulant dependence or abuse, respondents who indicated past year use or nonmedical use of hallucinogens, stimulants, or sedatives based solely on these special drug questions were categorized as NOT having past year dependence or abuse of the relevant substance regardless of how they answered the dependence and abuse questions.

Respondents might have provided ambiguous information about past year use of any individual substance, in which case these respondents were not asked the dependence and abuse questions for that substance.

Subsequently, these respondents could have been imputed to be past year users of the respective substance. In this situation, the dependence and abuse data were unknown; thus, these respondents were classified as not having dependence or abuse of the respective substance. Prescription stimulants are often prescribed for the treatment of attention-deficit hyperactivity disorder ADHD or obesity.

For example, amphetamines e. Although originally developed as a prescription stimulant, methamphetamine is no longer asked about in NSDUH as a prescription stimulant because it tends to be illegally manufactured and distributed. Prescription sedatives are often prescribed for the relief of sleep disorders such as insomnia. For the first time, NSDUH respondents in were asked to report any past year use of these drugs, including the use of one's own prescription medication as directed by a doctor as well as misuse.

Use of prescription psychotherapeutic drugs in the past year was fairly common in the United States. Of the four categories of prescription psychotherapeutic drugs presented in this report i.

In addition, approximately Adults aged 26 or older were more likely than youths or young adults to have used prescription pain relievers in the past year. Adults aged 26 or older were more likely than youths or young adults to have used prescription pain tranquilizers in the past year. Unlike the patterns for pain relievers and tranquilizers, young adults were more likely than youths or adults aged 26 or older to have used stimulants in the past year.

Thus, the overall estimate of 6. Among the population aged 12 or older in , Females were more likely than males to have used prescription pain relievers However, similar percentages of females and males used prescription stimulants in the past year 6.

People aged 12 or older who were not Hispanic were more likely than Hispanics to be past year users for each category of prescription psychotherapeutic drugs The past year use of psychotherapeutic drugs in ranged from The percentages of people aged 12 or older who used prescription pain relievers in the past year ranged from The percentages of people aged 12 or older who used prescription tranquilizers in the past year ranged from 4.

For prescription stimulants, the percentages of people aged 12 or older who reported use in the past year ranged from 2. Percentages of people aged 12 or older who used prescription sedatives in the past year ranged from 3. Among individuals aged 12 or older in , Among individuals aged 12 or older residing in large metropolitan areas, Percentages of individuals aged 12 or older who used prescription stimulants in the past year were 6. Percentages of individuals aged 12 or older who used prescription sedatives in the past year were 6.

NSDUH asked respondents in to identify the specific prescription pain relievers, tranquilizers, stimulants, and sedatives that they used in the past year. Names of similar prescription drugs e. For each prescription psychotherapeutic drug category, these specific prescription drugs were further categorized into subtypes within the overall category.

However, estimates typically were not made for the specific prescription drugs that respondents reported using because the data were based on respondent self-reports. For classification purposes, however, these reports would be equivalent. Estimates for the past year use of buprenorphine products and methadone among people aged 12 or older were 0.

These two products are used in medication-assisted treatment to help people reduce or quit their use of heroin or other opiates. For example, one of the six subtypes of tranquilizers was benzodiazepine tranquilizers , which was further subcategorized into four types of benzodiazepine tranquilizers, such as alprazolam products e.

The four categories of prescription drugs pain relievers, tranquilizers, stimulants, and sedatives in NSDUH cover many medications that currently are or have been available by prescription in the United States.

Misuse of these drugs is defined as use in any way not directed by a doctor, including use without a prescription of one's own; use in greater amounts, more often, or longer than told to take a drug; or use in any other way not directed by a doctor.

Misuse of over-the-counter drugs is not included in the definition of misuse. As noted previously, NSDUH reports combine the four prescription drug categories into a category referred to as "psychotherapeutics. Among people aged 12 or older, an estimated For example, approximately Although adults aged 26 or older were more likely than people in other age groups to have used prescription drugs in the past year, young adults were more likely than youths and adults aged 26 or older to have misused prescription psychotherapeutic drugs in this period.

In addition, youths were more likely than adults aged 26 or older to have misused stimulants in the past year. However, similar percentages of youths and adults aged 26 or older misused prescription pain relievers, tranquilizers, and sedatives in the past year. Among youths aged 12 to 17, 3.

These percentages correspond to , youths who misused prescription pain relievers, , who misused prescription tranquilizers, , who misused prescription stimulants, and , who misused prescription sedatives.

Percentages of young adults aged 18 to 25 who misused specific categories of prescription psychotherapeutic drugs were 8. These percentages correspond to 3. Among adults aged 26 or older, 4. These percentages correspond to 8. In particular, males aged 12 or older were more likely than their female counterparts to have misused any prescription psychotherapeutic drug in the past year 7.

Males also were more likely than females to have misused prescription pain relievers 5. However, males were less likely than females to have misused prescription sedatives in the past year 0. In , percentages of non-Hispanics and Hispanics aged 12 or older were similar for the misuse in the past year of any prescription psychotherapeutic drug 7. However, non-Hispanics were more likely than Hispanics to have misused prescription stimulants in the past year 2. The misuse of any prescription psychotherapeutic drug in the past year among individuals aged 12 or older in ranged from 3.

The misuse of prescription pain relievers in the past year ranged from 1. The misuse of prescription tranquilizers in the past year ranged from 0. The misuse of prescription stimulants in the past year ranged from 0. Estimates for the misuse of prescription sedatives in the past year among racial groups were below 1. Among individuals aged 12 or older in , 7. Most people who used prescription psychotherapeutic drugs in the past year did not misuse them.

For example, the NSDUH asks respondents aged 12 or older about their past year use of alcohol, tobacco, and several illicit drugs: Except for data that are collected on the use of alcohol in combination with the misuse of prescription drugs in the past month not included in this report , NSDUH does not assess whether respondents misused prescription drugs and used other substances at the same time.

This section provides estimates of past year prescription drug misuse among people who used other substances in that period, such as the percentage of past year alcohol users who misused prescription drugs in the past year. In , the following numbers of people aged 12 or older used other substances at least once in the past year regardless of whether they misused prescription drugs in the past year:.

Among the estimated The large majority of past year heroin users aged 12 or older also misused prescription psychotherapeutic drugs in the past year About a quarter Among past year heroin users aged 12 or older, Compared with the estimate of 2.

In addition, more than 1 in 4 past year users of Ecstasy In , the misuse of prescription sedatives in the past year among people aged 12 or older who used other substances in that period was not as pronounced as the misuse of pain relievers, tranquilizers, or stimulants.

In comparison, the percentages of users of other substances who misused sedatives in the past year ranged from 0. Adults are defined as having AMI if they had any mental, behavioral, or emotional disorder in the past year that met the Diagnostic and Statistical Manual of Mental Disorders , 4th edition DSM-IV , criteria excluding developmental disorders and substance use disorders.

This number who misused prescription psychotherapeutic drugs in the past year corresponds to In comparison, among adults who did not have a mental illness in the past year, 5. Among adults in who had AMI in the past year, about 1 in 9 These percentages correspond to 4. About 1 in 10 adults with SMI 9. Adults in who did not have a mental illness in the past year were less likely than adults with AMI or SMI to have misused prescription drugs in each of the four psychotherapeutic categories in the past year.

Among adults in who did not have a mental illness in the past year, 3. MDE is defined for both adults and adolescents using the diagnostic criteria from DSM-IV, although there are separate criteria for adults and youths. However, some wordings to the questions for adolescents were designed to make them more developmentally appropriate for youths. Data are presented separately for adults and adolescents because of the different wording of questions for adults and adolescents.

This number of adults who misused prescription psychotherapeutic drugs represents Adults who did not have an MDE in the past year were less likely than adults who had a past year MDE to misuse prescription psychotherapeutic drugs in the past year 6. Corresponding percentages among adults with a past year MDE were Adults in who did not have an MDE in the past year were less likely than adults who had an MDE to misuse prescription drugs in each of the psychotherapeutic categories in the past year.

Specifically, among adults who did not have an MDE in the past year, 4. In , an estimated 3. This number represents Among adolescents who did not have an MDE in the past year, 4.

These numbers correspond to 7. Adolescents in who did not have an MDE in the past year were less likely than their counterparts who had an MDE to misuse prescription drugs in each of the psychotherapeutic categories in the past year. Among adolescents who did not have an MDE in the past year, 3.

NSDUH respondents aged 18 or older were asked if at any time during the past 12 months they had thought seriously about trying to kill themselves. This section provides estimates of the misuse of prescription drugs among adults who had serious thoughts of suicide in the past year. However, NSDUH does not assess whether respondents misused prescription drugs while they were having serious thoughts of suicide.

Among adults who did not have serious thoughts of suicide in the past year, 6. Among adults who had serious thoughts of suicide in the past year, these numbers represent Adults who did not have serious thoughts of suicide in the past year were less likely than those who had serious thoughts of suicide to have misused prescription drugs in each of the psychotherapeutic categories in the past year.

Among adults who did not have serious thoughts of suicide in the past year, 4. As noted previously, NSDUH respondents in were asked to identify the specific prescription pain relievers, tranquilizers, stimulants, and sedatives that they used in the past year.

The remainder of this section presents estimates for the misuse of specific subtypes of prescription drugs in the past year. Individuals who misused alprazolam products represented 1. The number of people who misused amphetamine products in the past year represented 1.

In contrast to the 2. The number of people who misused zolpidem products in the past year represented 0. An estimated , people aged 12 or older, or 0. Respondents in the NSDUH who reported misuse of any of the four categories of prescription psychotherapeutic drugs in the past year were asked to recall the last prescription drug in that category that they misused in the past year. For the first time in NSDUH, respondents were asked to report their reasons for misusing the prescription drug that last time.

Respondents who reported more than one reason for misusing the last prescription drug were asked to report the main reason for misuse. If respondents reported only one reason for misusing their last prescription drug in a given psychotherapeutic category, then that reason was their main reason for misuse.

Except for "to relieve physical pain," the same reasons were presented for tranquilizers and sedatives; the first reason that was presented for these two psychotherapeutic categories was "to relax or relieve tension. In addition, respondents could report "some other reason" for their misuse of a particular psychotherapeutic drug and then specify a reason that applied to another psychotherapeutic category.

For example, respondents could specify that they also misused their last tranquilizer to relieve physical pain i. Among people aged 12 or older in who misused prescription pain relievers in the past year, the most commonly reported reason for their last misuse of a pain reliever was to relieve physical pain Even if the reason for misuse was to relieve physical pain, use without a prescription of one's own or use at a higher dosage or more often than prescribed still constituted misuse.

Other commonly reported reasons for the last misuse among people who misused pain relievers in the past year were to feel good or get high Less common reasons among past year misusers of pain relievers included to help with sleep 4. Among people aged 12 or older in who misused prescription tranquilizers in the past year, the most common reasons for misuse the last time were to relax or relieve tension However, these individuals misused tranquilizers to achieve the effect for which tranquilizers are prescribed.

Even if the reason for misuse was a reason for which tranquilizers are prescribed, use without a prescription, more often than prescribed, or at higher dosages than prescribed still constituted misuse. Less common reasons for misuse included experimenting to see what the drug was like 6.

In , the most commonly reported main reasons for the misuse of stimulants among people aged 12 or older who misused stimulants in the past year were to help be alert or stay awake Less commonly reported reasons for the last misuse of prescription stimulants among past year misusers were to experiment to see what the drug was like 5. Among people aged 12 or older in who misused prescription sedatives in the past year, the most common reason for the last misuse was to help with sleep Even if people took sedatives to help them sleep, this use constituted misuse if people took them without a prescription, more often than prescribed, or at higher dosages than prescribed.

Other reasons for the last misuse among people who misused sedatives in the past year were to relax or relieve tension Less commonly reported reasons included to help with feelings or emotions 3. If NSDUH respondents in reported that they misused a specific prescription psychotherapeutic drug e. The NSDUH measures whether an individual first misused all prescription drugs in a given psychotherapeutic category within the past 12 months i.

By definition, people who initiated the misuse of any psychotherapeutic drug within a category in the past 12 months will have had their first misuse at their current age or the year before their current age. For this reason, estimates are not included for the past year initiation of misuse for any prescription psychotherapeutic drug. Unlike previous sections, this section focuses on the number of people who were recent initiates for the misuse of drugs in specific categories of prescription psychotherapeutic drugs rather than on percentages.

Information on the number of recent initiates can be useful to policymakers and program planners for anticipating future needs for health services both in the short term and in the longer term.

However, care should be taken in interpreting apparent differences in the estimated numbers of initiates across population subgroups because some of these differences could reflect differences in the size of the respective subgroups.

This section also presents the average age at first misuse for prescription drugs among recent initiates of prescription drugs in a given psychotherapeutic category. Although the numbers of initiates are shown for initiates aged 12 or older as well as by age group, the average ages at first misuse in this report are limited to past year initiates aged 12 to 49 to avoid extreme values from older initiates influencing the averages.

In , there were 2. The average ages at first misuse in among recent initiates aged 12 to 49 were Historically, the number of past year initiates for the misuse of pain relievers has been second only to marijuana among illicit drugs.

This number of recent initiates includes 0. In , approximately , adolescents aged 12 to 17 1. This averages to approximately 1, adolescents each day who initiated the misuse of pain relievers. There were , young adults aged 18 to 25 1. These numbers average to about 1, young adults and about 3, adults aged 26 or older each day who initiated the misuse of pain relievers. In , approximately , adolescents aged 12 to 17 0.

Each day, therefore, about adolescents, 1, young adults, and 2, adults aged 26 or older initiated the misuse of tranquilizers. In , the estimated 1. These numbers of initiates include , females aged 12 or older 0. Approximately , adolescents aged 12 to 17 1. Thus, about adolescents per day, 1, young adults per day, and 1, adults aged 26 or older per day initiated the misuse of stimulants.

In , the approximately , people aged 12 or older who misused sedatives for the first time within the past year average to about 1, initiates per day for misuse of sedatives. About , females aged 12 or older 0. In , approximately 46, adolescents aged 12 to 17 0. Thus, about adolescents, young adults, and adults aged 26 or older initiated the misuse of sedatives each day in NSDUH includes a series of questions to estimate the percentage of the population aged 12 or older who had substance use disorders SUDs in the past 12 months.

Respondents were asked questions about prescription drug use disorders if they reported misuse of prescription drugs in the past 12 months. Because of the creation of a new section in the interview for methamphetamine see the "Introduction" , SUDs for prescription stimulants in do not include methamphetamine. In and earlier years, SUD estimates for prescription stimulants included data from respondents who used methamphetamine in the past year.

Instead, new questions were added to the survey in that ask about SUD symptoms that respondents specifically attributed to their use of methamphetamine in the past year, separate from SUD symptoms that were associated with the misuse of prescription stimulants. This number of people who had a prescription drug use disorder represents 1. An estimated , adolescents aged 12 to 17 in 0.

Among young adults aged 18 to 25, about , had a prescription drug use disorder in the past year 2. In , an estimated 2. This number represents 0. Approximately , young adults aged 18 to 25 and 1. These numbers represent 1. An estimated 77, adolescents aged 12 to 17 in 0.

Approximately , young adults aged 18 to 25 0. About 38, adolescents aged 12 to 17 in 0. Approximately , young adults aged 18 to 25 and , adults aged 26 or older in had a stimulant use disorder in the past year. These numbers represent 0. An estimated 26, adolescents aged 12 to 17 0. Approximately 22, young adults aged 18 to 25 and , adults aged 26 or older in had a sedative use disorder in the past year. NSDUH respondents who used alcohol or illicit drugs in their lifetime are asked whether they ever received substance use treatment i.

Substance use treatment refers to treatment received for illicit drug or alcohol use or for medical problems associated with the use of illicit drugs or alcohol. This includes treatment received in the past year at any location, such as a hospital inpatient , rehabilitation facility outpatient or inpatient , mental health center, emergency room, private doctor's office, prison or jail, or a self-help group, such as Alcoholics Anonymous or Narcotics Anonymous. Respondents who reported receiving substance use treatment in the past year had the opportunity to indicate the specific substances for which they received treatment during their most recent e.

Data on the substances for which people received their most recent treatment are not mutually exclusive because respondents could indicate that they received treatment for their use of more than one substance. The , people who received treatment for the misuse of pain relievers during their most recent treatment in the past year represent An estimated , people aged 12 or older received treatment for tranquilizer misuse during their most recent treatment in the past year 8.

This section presents information for how all people aged 12 or older who misused prescription pain relievers in the past year obtained these pain relievers the last time they misused them. This section also discusses how past year misusers of pain relievers obtained pain relievers the last time they misused them according to approximately increasing levels of problem misuse. More than half About one third of people who misused pain relievers in the past year About 1 in 20 people who misused pain relievers in the past year 4.

Another way of understanding the misuse of prescription pain relievers is to examine whether the sources for the most recently misused prescription pain relievers vary by the type of misuser of pain relievers.

These user types were defined in terms of approximately increasing levels of misuse. Specifically, past year misusers of pain relievers were categorized into the following mutually exclusive groups: As noted previously, individuals who misused pain relievers in the past year were defined as having a pain reliever use disorder in the past year based on criteria specified in DSM-IV.

Obtaining pain relievers from a friend or relative was the most common source for both past year initiates This source was followed by obtaining pain relievers through prescription s or health care providers, which was reported by In comparison, the most common source for past year misusers with a pain reliever use disorder was through prescription s or health care providers Past year misusers with a pain reliever use disorder also were more likely than misusers in the other two groups to have obtained their last prescription pain relievers from a drug dealer or other stranger More than 1 in 8 past year misusers with a pain reliever use disorder Past year misusers with a pain reliever use disorder also were less likely to obtain their last pain relievers from a friend or relative for free A number of changes were made to the NSDUH questionnaire and data collection procedures to collect new information and to address current substance use and mental health policy and research needs.

As noted in the section at the beginning of the report titled "Notable Questionnaire Changes for the NSDUH," these changes included the redesign of the prescription drug questions. Collecting more detailed information on use, misuse, and recent initiation of a comprehensive set of specific prescription drugs was determined to be more useful for policy and research purposes, in part because of public health concerns about increases in addiction, overdoses, and deaths involving prescription drugs.

This section provides a brief summary of enhancements to the NSDUH prescription drug questions and some analyses that are now possible with these new prescription drug data. Notable limitations are also summarized. Several enhancements or improvements were made to the prescription drug questions in the NSDUH, as described below. The definition of misuse was changed to focus on specific behaviors that constitute misuse and to incorporate more ways in which people misuse prescription drugs, including overuse of medication despite having a prescription.

The definition of misuse before included a behavior i. Also, use "for the experience or feeling" that a drug caused could be misinterpreted by respondents to apply to use of prescribed medications for their intended effects e. Because of the focus of the NSDUH questions on the past year reference period for the use and misuse of specific prescription drugs i. Decisions to add specific prescription drugs to the questionnaire were based on a number of factors, including identification of recently approved prescription drugs that were not included in the NSDUH questionnaire for the last major redesign in , changes in prescribing practices e.

In turn, prescription drugs that are no longer available in the United States were removed from the questionnaire, despite some of these having been commonly misused drugs in the past e. In particular, more than half of the stimulants and sedatives in the questionnaire had been discontinued or were no longer legally available in the United States and were therefore not included in the questionnaire.

Keeping a set of measures in the survey that have undergone little or no change over time permits the measurement of trends. However, presenting respondents with a less relevant set of prescription drugs erodes the validity of the trend data for prescription drug misuse, even if the NSDUH questions remain unchanged. Because the NSDUH questionnaire includes subsequent questions on misuse, it is now possible to estimate the percentages of past year users of different categories of psychotherapeutic drugs who reported misuse.

Although not a focus of this report, it also is possible with these data to estimate the number of people who used their own medication only as directed by a doctor by subtracting the number of people who reported misuse from the number who reported any use. Note that people who reported any use of a specific medication and also reported misuse of the same medication are counted as misusers because they misused a medication at least once in the past year.

However, it is not possible to differentiate respondents whose only use in the past year involved misuse from those who used a given medication as directed and who also misused the same medication at some other time in the past year. The prescription drug redesign allows for prescription drug use and misuse to be grouped by chemically related prescription drugs e. Data on specific prescription drugs also can allow drugs to be categorized according to whether the active ingredient is intended to be released fairly rapidly into a person's system i.

Because extended-release prescription drugs typically contain a higher dosage of the active ingredient than their immediate-release counterparts, tampering with extended-release medications e. However, taking a large number of pills for an immediate-release drug could have the same potentially dangerous effect. Thus, understanding patterns of misuse of immediate-release and extended-release prescription drugs can inform decisionmaking about prescribing practices e.

NSDUH now asks respondents to report whether they misused prescription drugs in the following ways:. Although data from these questions were not presented in this report, these questions can be used to assess whether drugs in certain prescription psychotherapeutic categories are more likely to be misused in specific ways compared with other categories of prescription drugs or if ways of misuse vary by respondent characteristics e.

In addition, it would be useful to understand the ways in which people misused prescription drugs in combination with their motivations for misuse see below. NSDUH now asks respondents who misused prescription drugs in a given category in the past year to report why they misused prescription drugs for their last episode of misuse. The specific reasons for misuse are listed below, along with the prescription drug categories to which these reasons applied:. Analyzing data on motivations for misuse according to the ways in which prescription drugs are being misused and how people obtained prescription drugs will be useful for identifying a richer set of social determinants and other risk factors that ultimately could be used by policymakers, researchers, and health care providers in the development of more focused prevention efforts and treatment interventions.

Although the previously described enhancements to the NSDUH prescription drug questions will provide a richer set of data for researchers and policymakers, there also are some important limitations to note that are associated with the changes to these questions. Because of the changes that were described previously, the estimates from the NSDUH for all prescription drug measures are not comparable with corresponding estimates that existed in prior survey years, including estimates of misuse, past year initiation of prescription drug misuse, and prescription drug use disorders.

The changes in the way that lifetime prescription drug misuse was measured appear to have affected the reporting of lifetime misuse of prescription drugs. In particular, the redesigned questions provided fewer questions and cues to aid respondents in recalling whether they misused any prescription psychotherapeutic drug in a given category more than 12 months prior to the interview date.

With the increase in questions asking about specific prescription drugs that were used in the past year, there were fewer questions asking about lifetime use of specific prescription drugs.

The redesigned questions also did not provide examples of prescription drugs that were no longer available by prescription in the United States but may have been historically important e. As a consequence, respondents who did not misuse prescription drugs in the past year but who did so in their lifetime may have underreported lifetime misuse in compared with the situation in prior years.

Therefore, both lifetime prescription drug use and misuse measures are not reported for Prior to , NSDUH respondents who reported that they misused one or more specific prescription psychotherapeutic drugs in a given category in their lifetime were asked to report how old they were when they first misused any prescription drug in that category. This question sequence i. This questioning sequence remained the same in for all substances except for prescription drugs. For prescription drugs, questions about the first time that respondents misused prescription drugs were limited to the specific prescription drugs that respondents misused in the past 12 months.

Specifically, if NSDUH respondents reported that they misused a particular prescription psychotherapeutic drug in the past 12 months, they were asked to report their age when they first misused it. Because initiation data in the NSDUH were not collected for respondents who reported lifetime but not past year misuse, an additional issue for the redesigned prescription drug questions is that limited data are available for establishing the temporal sequence of initiation for misuse of prescription drugs relative to the initiation of use for other substances.

For example, if a respondent initiated use of heroin in the past year and reported misuse of prescription pain relievers more than 12 months prior to being interviewed, information was not available in on the period of time between the initiation of the misuse of pain relievers and the first use of heroin. As noted in the preceding section, there is evidence of underreporting of lifetime but not past year misuse of prescription drugs compared with prior years.

This potential underreporting of lifetime misuse also has two effects on estimates in for initiation of prescription drug misuse. First, underreporting of lifetime misuse would increase the estimated size of the population who are defined as being "at risk" for initiation; respondents who initiated use or misuse of a substance more than 12 months ago can no longer be "at risk" for initiation in the past 12 months. Second, the potential for respondents to underreport lifetime misuse has affected the estimation of past year initiation of misuse for any prescription psychotherapeutic drug i.

If a respondent was defined as being a past year initiate for misuse of one category of prescription drugs e. Likewise, respondents who underreported lifetime but not past year misuse of prescription drugs could be misclassified as initiating the use or misuse of any illicit drug in the past year.

Therefore, estimates for are still reported for past year initiation for the individual prescription drug categories i. However, estimates in are no longer reported for the initiation of misuse of any prescription psychotherapeutic drug or any illicit drug in the past year. Further studies are needed to evaluate how this underreporting has affected the estimates for these aggregate initiation measures.

Prescription drug use and misuse in the United States: Key substance use and mental health indicators in the United States: Some of these estimated numbers are not included in figures or tables in the report but may be found in the detailed tables for the NSDUH available at http: Misuse of prescription drugs: Prevalence, correlates, and comorbidity of nonmedical prescription drug use and drug use disorders in the United States: Journal of Clinical Psychiatry, 67 , Nonmedical use of prescription opioids: Motive and ubiquity issues.

Journal of Pain, 9 , Although some people in the general population of the United States are outside of the civilian, noninstitutionalized population, information from the U. See the following reference: In particular, Tables A.

Center for Behavioral Health Statistics and Quality. Methodological summary and definitions. Implications for data users. National Survey on Drug Use and Health: See endnote 7 for the reference.

Because respondents were allowed to choose more than one racial group, a "two or more races" category is presented that includes persons who reported more than one category among the seven basic groups listed in the survey question white, black or African American, American Indian or Alaska Native, Native Hawaiian, Other Pacific Islander, Asian, Other.

The category "Hispanic or Latino" includes Hispanics of any race. Also, more detailed categories describing specific subgroups were obtained from survey respondents if they reported either Asian race or Hispanic ethnicity. Office of Management and Budget. Revisions to the standards for the classification of federal data on race and ethnicity. Federal Register, 62 , These regions consist of the following groups of states, including the District of Columbia:.

For this purpose, counties are grouped based on the rural-urban continuum codes. These codes are updated approximately every 10 years and are available at http: See the following references:. Rural-urban continuum codes for metro and non-metro counties , Staff Report No. Department of Agriculture, Economic Research Service. Revised definitions of metropolitan statistical areas, new definitions of micropolitan statistical areas and combined statistical areas, and guidance on uses of the statistical definitions of these areas OMB Bulletin No.

Other prescription pain relievers could include products that are similar to the specific pain relievers that were listed previously. Other prescription tranquilizers could include products that are similar to the specific tranquilizers that were listed previously. Other prescription stimulants could include products that are similar to the specific stimulants that were listed previously.

Since , methamphetamine has not been included as a prescription stimulant. Other prescription sedatives could include products that are similar to the specific sedatives that were listed previously.

Adults were first asked whether they ever had a period in their lifetime lasting several days or longer when any of the following was true for most of the day: Adults who reported any of these problems were asked further questions about having an MDE in their lifetime, including whether they had at least five of nine symptoms in the same 2-week period in their lifetime; at least one of the symptoms needed to be having a depressed mood or loss of interest or pleasure in daily activities.

Those who had lifetime MDE were asked if they had a period of time in the past 12 months when they felt depressed or lost interest or pleasure in daily activities for 2 weeks or longer, and they reported that they had some of their other lifetime MDE symptoms in the past 12 months. These adults were defined as having past year MDE.

Adolescents who reported any of these problems were asked further questions about having an MDE in their lifetime, including whether they had at least five of nine symptoms in the same 2-week period in their lifetime; at least one of the symptoms needed to be having a depressed mood or loss of interest or pleasure in daily activities.

Unlike in the questions for adults, adolescents who reported gaining weight without trying were asked if this occurred because they were growing. These adolescents were defined as having past year MDE. Suicidal thoughts and behavior among adults: NSDUH respondents who reported that they misused a particular prescription drug in the past 12 months are asked to report their age when they first misused it.

Respondents who reported first misuse of a prescription drug within a year of their current age which is within 24 months of the date of the interview also are asked to report the year and month when they first misused it. Risk and protective factors and initiation of substance use: Coming to terms with the nonmedical use of prescription medications.

Substance Abuse Treatment, Prevention, and Policy, 3 For substances such as hallucinogens, respondents were asked whether they ever used specific substances in that category. If respondents answered affirmatively for one or more of the specific substances, they were asked to report their age when they first used any drug in that category e. For each prescription psychotherapeutic drug category, respondents first were asked whether they used a series of specific prescription drugs in the past 12 months.

To aid respondents in recalling whether they used a specific prescription drug in the past 12 months, electronic images of pills or other forms of the drugs where applicable were shown to respondents on the computer screen; a document that shows the prescription drug images for the NSDUH is available at http: Respondents who reported use of prescription psychotherapeutics in any of these four psychotherapeutic categories in the past 12 months or the lifetime period were defined as users of any prescription psychotherapeutic drug.

In order to identify past year misusers of prescription psychotherapeutic drugs, respondents who reported that they used specific prescription psychotherapeutic drugs in the past 12 months were shown a list of the drugs that they used in the past 12 months and were asked for each drug whether they used it in the past 12 months "in any way not directed by a doctor" i.

If respondents reported misuse of one or more specific drugs within a psychotherapeutic category in the past 12 months, they were asked whether they used any drug in that category e. This question was used to estimate past month or "current" misuse. Respondents who reported misuse of prescription psychotherapeutics in any of these four psychotherapeutic categories in the past 30 days, past 12 months, or in the lifetime period were defined as having misused any prescription psychotherapeutic drug.

Unlike prior years, the NSDUH reports and tables no longer refer to "prescription-type" psychotherapeutic drugs because questions about use of methamphetamine in are asked separately from questions about the use and misuse of prescription psychotherapeutic drugs.

Prior to , methamphetamine was included in the section of the interview for prescription stimulants. However, most methamphetamine that is used in the United States is produced in clandestine laboratories rather than by the pharmaceutical industry.

Thus, beginning in , methamphetamine questions were removed from the prescription stimulants section and were included in a new, separate section of the interview. For these reasons, it is not necessary for the NSDUH to refer to "prescription-type" psychotherapeutic drugs. Department of Justice to place controlled substances into "schedules. Altogether, the questionnaire asked about the past year use or misuse of 37 specific pain relievers.

In comparison, the questionnaire asked about the lifetime misuse of 27 specific pain relievers, including some that are no longer available by prescription in the United States e. In , pain relievers that contain hydrocodone plus acetaminophen e. For this report, codeine products are included in estimates of the use and misuse of prescription pain relievers as a whole. Prescription opioids are substances that act in the central nervous system to reduce the perception of pain.

Although all of the pain reliever subtypes are opioids, the term "pain relievers" in NSDUH is not synonymous with "opioids" because respondents could specify that they misused other pain relievers besides the ones they were asked about in the questionnaire.

These other pain relievers could include nonopioids such as nonsteroidal anti-inflammatory drugs that are not classified as controlled substances e. Altogether, the questionnaire asked about the past year use or misuse of 15 specific tranquilizers.

Although the questionnaire asked about the lifetime misuse of nominally more tranquilizers i. The drugs that were included in the tranquilizers section of the NSDUH interview included benzodiazepines that are prescribed as tranquilizers e. These three substances had been included in the tranquilizers section of the interview in the NSDUH and had been kept for the questionnaire based on the results of field testing of the planned questionnaire and review by pharmacists of the proposed specific prescription drugs for the questionnaire.

Buspirone and hydroxyzine have been dropped for , but cyclobenzaprine has been retained for the NSDUH questionnaire. Although cyclobenzaprine is not scheduled as a controlled substance, it is classified as a muscle relaxant. Although both tranquilizers and sedatives cause drowsiness, an important distinction between these drug categories is that tranquilizers are prescribed for anxiety relief or to relieve muscle spasms, whereas sedatives are prescribed specifically for the relief of insomnia.

In particular, benzodiazepine drugs that are prescribed as tranquilizers typically are metabolized more slowly than benzodiazepines that are prescribed as sedatives.

Altogether, the questionnaire asked about the past year use or misuse of 26 specific stimulants. This number of stimulants in is slightly more than the 21 specific stimulants in the questionnaire for which respondents were asked about lifetime misuse, which included methamphetamine. Not counting methamphetamine, more than half of the stimulants in the questionnaire are no longer available by prescription in the United States e.

Thus, unlike the other prescription drug categories, the intended purpose of prescribing stimulants is not always apparent from the name of the category. In contrast, the reason for prescribing pain relievers, tranquilizers, or sedatives is implied in the category name i. However, this did not occur for Altogether, the questionnaire asked about the past year use or misuse of 14 specific sedatives. Although the questionnaire asked about the lifetime misuse of nominally more sedatives i.

A design in which half of the sample received the original question about barbiturates and the other half received a question about "sedatives, which include barbiturates," yielded almost identical estimates for the two different question forms among 12th graders.

The researchers concluded that users of sedatives that were not barbiturates were including these sedatives in their answers.

Prior to the NSDUH, the term "nonmedical use" was used in NSDUH reports to describe use of the prescription drugs that were not prescribed for individuals or that individuals took only for the experience or feeling that the drugs caused. As noted previously, questions in the NSDUH for prescription drugs were revised to ask about use "in any way that a doctor did not direct you to use them. Potential alternatives to the term "nonmedical use" include "extramedical use," "misuse," and "abuse"; these terms have different meanings and therefore are not interchangeable.

Nevertheless, the term "misuse" appears for multiple reasons to be the most appropriate and parsimonious term to describe the types of behaviors that are covered by the new NSDUH prescription drug questions for Butler and colleagues defined substance misuse as "the use of any drug in a manner other than how it is indicated or prescribed. To address the priorities and needs of policymakers and researchers, the changes listed below were implemented as part of the redesign of the prescription drug questions for the NSDUH.

This section also discusses expected improvements to the data because of these changes. Because of these changes, new baselines started in for all prescription drug measures, including measures for prescription psychotherapeutics overall and for categories of prescription psychotherapeutics i. Specifically, new baselines were established for the following measures that existed before Unlike the other prescription drug measures that were described previously, corresponding measures did not exist before for these questions.

In addition, field testing of the redesigned prescription drug questions suggested that the focus on the past 12 months could cause some respondents to underreport the use or misuse of prescription psychotherapeutic drugs that occurred in their lifetime but not in the past 12 months. This section discusses the following issues related to the measurement of prescription drug use and misuse in the NSDUH:. A separate methodological summary report for the NSDUH contains information about additional data processing and measurement issues for the use and misuse of prescription drugs, including the following: Detailed documentation of the editing and imputation procedures for the prescription drug data also will be provided in a forthcoming report on general editing and imputation procedures for the NSDUH; this report will be included in the NSDUH Methodological Resource Book and will be available at http: The report of editing and imputation procedures for also will discuss procedures for handling answers that respondents typed for other prescription drugs that they misused, other reasons for misuse, and other sources of prescription drugs also referred to as "OTHER, Specify" data , including procedures to assign numeric codes to the typed responses and procedures for using these "OTHER, Specify" data to edit the prescription drug data.

Questions in the NSDUH for prescription pain relievers were used to define the following 10 specific subtypes of opioid pain relievers:.

Separate estimates were not produced for prescription drugs that are available both as brand name drugs and as generic equivalents e. Consequently, some respondents could report the use or misuse of brand name drugs when, in fact, they took the generic equivalent.

Conversely, respondents who recently switched prescriptions from a generic to a corresponding brand name drug could misreport that they used or misused the generic when their behavior actually applied to the brand name drug. For these types of prescription drugs, therefore, only combined estimates were produced that were based on the use or misuse of either brand name drugs or their generic equivalents.

Questions in the NSDUH for specific prescription tranquilizers were used to define the following broad subtypes of prescription tranquilizers not counting other tranquilizers:.

These tables also list brand names which have been discontinued in the United States that respondents may recognize for cyclobenzaprine, buspirone, hydroxyzine, and meprobamate. Questions in the NSDUH for specific prescription stimulants were used to define the following broad subtypes of prescription stimulants not counting other stimulants:. In particular, the amphetamine and methylphenidate products in these tables are primarily prescribed for the treatment of ADHD.

Questions in the NSDUH for specific prescription sedatives were used to define the following broad subtypes of prescription sedatives not counting other sedatives:.

The variables that were used to estimate any use and misuse in the past year for the overall categories of prescription pain relievers, tranquilizers, stimulants, and sedatives included statistical imputation to account for item nonresponse and therefore had no missing data. Past year initiation variables for prescription drug misuse and SUD variables for prescription drugs in also were imputed. Respondents with missing data for the main reason for the last misuse and for the source of the last prescription pain reliever were excluded from the analyses.

Bias may result when respondents with missing data are excluded from the analysis. For population totals i. When population proportions are estimated for these two measures, there may or may not be bias, and the bias can be negative or positive. The direction and magnitude of the bias for proportions depend on how different the item respondents are from the item nonrespondents with respect to the outcome of interest.

In addition, respondents could have missing data for whether they used or misused specific subtypes of prescription drugs in the past year. For example, respondents were presented with a list of prescription pain relievers containing hydrocodone and were asked to report which, if any, of these they had used in the past 12 months.

Except in special situations, respondents who answered "don't know" or "refused" when presented with this list would have missing data for the past year use of hydrocodone products. In turn, these respondents were not asked whether they misused specific hydrocodone products in the past year. During the processing, missing values in variables pertaining to subtypes of prescription drugs were coded as "no use" or "no misuse" in the past 12 months.

Estimates for subtypes of prescription drugs were then produced based on the data from respondents who did not have missing data and the respondents with missing data who were assumed not to have used or misused that subtype. However, some of these respondents with missing data could have used or misused a specific subtype of prescription drugs in the past 12 months, which will cause a negative bias in the estimates.

These true percentages are not known but can be estimated by the difference in estimates, depending on whether respondents with missing data are excluded from the analysis or are included i. However, low percentages of NSDUH respondents in had missing data for most prescription drug measures.

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