National Survey on Drug Use and Health (NSDUH-2018)

Parent Series Details:

Background

The National Survey on Drug Use and Health (NSDUH) series, formerly titled National Household Survey on Drug Abuse, is a major source of statistical information on the use of illicit drugs, alcohol, and tobacco and on mental health issues among members of the U.S. civilian, non-institutional population aged 12 or older. The survey tracks trends in specific substance use and mental illness measures and assesses the consequences of these conditions by examining mental and/or substance use disorders and treatment for these disorders.

Examples of uses of NSDUH data include the identification of groups at high risk for initiation of substance use and issues among those with co-occurring substance use disorders and mental illness.

NSDUH public-use data files are available for download in SAS, SPSS, STATA and ASCII formats, and online analysis with SDA. NSDUH restricted-use data files are available for online analysis with the R-DAS.

The NSDUH is sponsored by the Center for Behavioral Health Statistics and Quality (formerly Office of Applied Studies), Substance Abuse and Mental Health Services Administration. For more information, visit the NSDUH website.

NSDUH State and Substate Estimates

Due to disclosure limitations for respondent confidentiality, a state variable is not included in public-release datasets. The data tables on SAMHSA’s site and the interactive NSDUH State and Substate Estimates tools use the full non-restricted analytic file that includes the state variable. 

NSDUH restricted-use data availability information is here:  https://www.cdc.gov/rdc/b1datatype/nsduh.htm.

SAMHSA’s restricted-use data analysis system (RDAS) is an online crosstab tool that includes restricted data, including certain geographic identifiers, like state. https://rdas.samhsa.gov/#/.

NSDUH state and substate estimates are located here:

1999-2015 NSDUH Small Area Estimation

state_saes_final.sas7bdat
NSDUH-99-15-State-SAE-Documentation-10-5-17.docx

NSDUH Variable Crosswalk Charts

PUFVariableCrosswalkChart_2012.xlsx
PUFVariableCrosswalkChart_2013.xlsx
PUFVariableCrosswalkChart_2014.xlsx
PUFVariableCrosswalkChart_2015.xlsx
PUFVariableCrosswalkChart_2016.xlsx
PUFVariableCrosswalkChart_2017.xlsx

NSDUH Reports and Detailed Tables

NSDUH Questionnaire Details

The population of the NSDUH series is the general civilian population aged 12 and older in the United States. Questions include age at first use, as well as lifetime, annual, and past-month usage for the following drugs: alcohol, marijuana, cocaine (including crack), hallucinogens, heroin, inhalants, tobacco, pain relievers, tranquilizers, stimulants, and sedatives. The survey covers substance abuse treatment history and perceived need for treatment, and includes questions from the Diagnostic and Statistical Manual (DSM) of Mental Disorders that allow diagnostic criteria to be applied.

Respondents were also asked about personal and family income sources and amounts, health care access and coverage, illegal activities and arrest record, problems resulting from the use of drugs, perceptions of risks, and needle-sharing. Demographic data include gender, race, age, ethnicity, educational level, job status, income level, veteran status, household composition, and population density.

The questionnaire was significantly redesigned in 1994. The 1994 survey included for the first time a rural population supplement to allow separate estimates to be calculated for this population. Other modules have been added each year and retained in subsequent years: mental health and access to care (1994-B); risk/availability of drugs (1996); cigar smoking and new questions on marijuana and cocaine use (1997); question series asked only of respondents aged 12 to 17 (1997); questions on tobacco brand (1999); marijuana purchase questions (2001); prior marijuana and cigarette use, additional questions on drug treatment, adult mental health services, and social environment (2003); and adult and adolescent depression questions derived from the National Comorbidity Survey, Replication (NCS-R) and National Comorbidity Survey, Adolescent (NCS-A) (2004).

Survey administration and sample design were improved with the implementation of the 1999 survey, and additional improvements were made in 2002. Since 1999, the survey sample has employed a 50-state design with an independent, multistage area probability sample for each of the 50 states and the District of Columbia. At this time, the collection mode of the survey changed from personal interviews and self-enumerated answer sheets to using computer-assisted personal interviews and audio computer-assisted self-interviews. In 2002, the survey’s title was officially changed to the National Survey on Drug Use and Health (NSDUH).

Since 2002, participants are given $30 for participating in the study. This resulted in an increase in participation rates from the years prior to 2002. Also, in 2002 and 2011, the new population data from the 2000 and 2010 decennial Censuses, respectively, became available for use in the sample weighting procedures. For these reasons, data gathered for 2002 and beyond cannot validly be compared to data prior to 2002.

NSDUH underwent a partial redesign in 2015, so there are several measures that “broke trends” in 2015, meaning that estimates from 2015 and later are no longer comparable to their 2014 and earlier counterparts. This also means that you cannot pool data across incomparable years. For affected measures, you will likely only be able to look at the 2002-2014 timeframe to pool enough years of comparable data to get a sufficient sample size at the county level. Measures that were not affected can be pooled through 2015. More information on the partial 2015 redesign and its effects on estimates is available here: https://www.samhsa.gov/data/sites/default/files/NSDUH-TrendBreak-2015.pdf


Study Details:

The target population for the 2018 survey was the same as has been defined since the 1991 survey: the civilian, noninstitutionalized population of the United States (including civilians living on military bases) who were 12 years of age or older at the time of the survey. Before 1991, the sample was drawn from the household population of the contiguous 48 states. Residents of Alaska and Hawaii were added to the sample population in 1991, as were residents of noninstitutional group quarters (e.g., college dormitories, group homes, civilians dwelling on military installations) and persons with no permanent residence (homeless people in shelters and long-term residents of single rooms in hotels). In addition, six special-interest metropolitan statistical areas (MSAs) were oversampled in 1991. The 1992 and 1993 surveys retained the oversampling of the six MSAs and also were designed to provide quarterly as well as annual estimates.

Since 1999, the survey sample has employed a 50-state design with an independent, multistage area probability sample for each of the 50 states and the District of Columbia. For the 1999 through 2013 surveys, the 8 states with the largest populations (which together account for 48 percent of the total U.S. population aged 12 or older according to the 2010 census) were designated as large sample states (California, Florida, Illinois, Michigan, New York, Ohio, Pennsylvania, and Texas) with a target sample size of 3,600, and the remaining 42 states and the District of Columbia had target sample sizes of 900. The 2014 through 2017 sample redesign allowed for a more cost-efficient sample allocation to the largest states, while maintaining sufficient sample sizes in the smaller states to support small area estimation at the state and substate levels. A large reserve sample of area clusters or segments was selected at the time the 2014 through 2017 NSDUH sample was selected, which is being used to field the 2018 through 2022 NSDUHs. Thus, the 2018 through 2022 NSDUH designs simply continue the coordinated design. The 2014 through 2022 NSDUHs were designed to yield 4,560 completed interviews in California; 3,300 completed interviews each in Florida, New York, and Texas; 2,400 completed interviews each in Illinois, Michigan, Ohio, and Pennsylvania; 1,500 completed interviews each in Georgia, New Jersey, North Carolina, and Virginia; 967 completed interviews in Hawaii; and 960 completed interviews in each of the remaining 37 states and the District of Columbia. Consistent with previous designs, the 2014 through 2022 design also oversamples youths aged 12 to 17 and young adults aged 18 to 25. However, the 2014 through 2022 design places more sample in the 26 or older age groups to more accurately estimate drug use and related mental health measures among the aging population. The 2018 sample was allocated to age groups as follows: 25 percent for youths aged 12 to 17, 25 percent for young adults aged 18 to 25, 15 percent for adults aged 26 to 34, 20 percent for adults aged 35 to 49, and 15 percent for adults aged 50 or older.

Important methodological differences since 2002 also have affected the comparability of estimates from 1999 to 2001 with estimates from 2002 and later years. As noted above, the survey's name was changed from the National Household Survey on Drug Abuse (NHSDA) to the National Survey on Drug Use and Health (NSDUH) in 2002. In addition to the survey's name change, each NSDUH respondent since 2002 has been given an incentive of $30. These changes resulted in some improvement in the survey response rate. The changes also affected respondents' reporting of many critical items that are the basis of prevalence measures reported by the survey each year. Further, the data could have been affected by  improved data collection quality control procedures introduced in the survey beginning in 2001. In addition, new population data from the 2000 decennial census became available for use in NSDUH's sample weighting procedures, resulting in another discontinuity between estimates since 2002 and those prior to 2002. Where estimates in 2018 are still comparable with those from prior years, analyses of the effects of each of these factors on NSDUH estimates have shown that the 2002 to 2018 data should not be compared with 2001 and earlier data to assess changes over time. For measures comparable across the years being analyzed, however, comparisons may be made between 2002 and surveys in subsequent years, including this one, as noted above.

A description of the 2018 survey, including more detailed information on sample issues, can be found in several NSDUH documents that discuss methodological issues for 2018 or present some key 2018 findings in tabular, graphical, and report formats. The following 2018 NSDUH documents were released simultaneously on August 20, 2019:

  • Center for Behavioral Health Statistics and Quality. (2019). 2018 National Survey on Drug Use and Health: Methodological summary and definitions. Retrieved from https://www.samhsa.gov/data/
  • Substance Abuse and Mental Health Services Administration. (2019). Key substance use and mental health indicators in the United States: Results from the 2018 National Survey on Drug Use and Health (HHS Publication No. PEP19-5068,  NSDUH Series H-54). Rockville, MD: Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration. Retrieved from https://www.samhsa.gov/data/
  • Center for Behavioral Health Statistics and Quality. (2019). Results from the 2018 National Survey on Drug Use and Health: Detailed tables. Retrieved from https://www.samhsa.gov/data/ 

Study Scope

Time period: 
2018
Collection date: 
2018
Geographic coverage : 
United States
Unit of observation: 
individual
Data types: 
survey data
Universe: 
Civilian, noninstitutionalized population of the United States aged 12 and older, including residents of noninstitutional group quarters such as college dormitories, group homes, shelters, rooming houses, and civilians dwelling on military installations.
Notes: 

NSDUH is the primary nationally representative source of annual estimates of drug use and mental illness among civilian members of the noninstitutionalized population in the United States. Most of the questions in NSDUH are administered with ACASI, which is designed to provide the respondent with a highly private and confidential mode for responding to questions in order to increase the level of honest reporting of illicit drug use and other sensitive behaviors. In addition, the large and dispersed NSDUH sample enables not only state-level estimates, but also estimates for substate areas.

Although NSDUH is useful for many purposes, it has certain limitations. First, the data are based on self-reports of drug use, and their value depends on respondents' truthfulness and memory. Although some experimental studies have established the validity of self-reported data in similar contexts and NSDUH procedures were designed to encourage honesty and recall, some underreporting and overreporting may take place. To aid respondent recall, the prescription drug questions in 2018 allowed respondents to report any use or misuse in the past 12 months of specific related medications (e.g., the tranquilizers Xanax®, Xanax® XR, generic alprazolam, and generic extended-release alprazolam). These self-reports capture information on the use or misuse of prescription drugs that contain a given active ingredient. However, these self-reports are not necessarily accurate for identifying the exact drugs respondents took, especially when respondents identify certain drugs by their brand names (e.g., if a respondent actually took the generic drug alprazolam but reported use or misuse of the brand name tranquilizer Xanax® because of name recognition). For this reason, the public use file includes recoded variables for subtypes of related prescription drugs (e.g., alprazolam products) but with few exceptions does not include variables for individual prescription drugs.

Second, the survey is cross-sectional rather than longitudinal. That is, individuals were interviewed only once and were not followed for additional interviews in subsequent years. Each year's survey, therefore, provides an overview of the prevalence of drug use at a specific point in time rather than a view of how drug use changes over time for specific individuals.

Third, because the target population of the survey is defined as the civilian, noninstitutionalized population of the United States, a small proportion (approximately 3 percent) of the population is excluded.9 The subpopulations excluded are members of the
active-duty military and individuals in institutional group quarters (e.g., hospitals, prisons, nursing homes, and treatment centers). If the drug use of these groups differs from that of the civilian, noninstitutionalized population, NSDUH may provide slightly inaccurate estimates of substance use and mental health in the total population. This may be particularly true for prevalence estimates for less commonly used drugs, such as heroin.

Subject Terms: 
  • addiction
  • alcohol
  • alcohol abuse
  • alcohol consumption
  • amphetamines
  • barbiturates
  • cocaine
  • controlled drugs
  • crack cocaine
  • demographic characteristics
  • depression (psychology)
  • drinking behavior
  • drug abuse
  • drug dependence
  • drug treatment
  • drug use
  • drugs
  • employment
  • hallucinogens
  • health care
  • heroin
  • households
  • income
  • inhalants
  • marijuana
  • mental health
  • mental health services
  • methamphetamine
  • pregnancy
  • prescription drugs
  • sedatives
  • smoking
  • stimulants
  • substance abuse
  • substance abuse treatment
  • tobacco use
  • tranquilizers
  • youths

Study Methodology

Mode of data collection: 
CAI methods
Sample: 
Like the 1999 to 2017 surveys, the 2018 survey was conducted using CAI methods. This survey also allows for improved state estimates based on minimum sample sizes per state. The target sample size of 67,507 allows SAMHSA to continue reporting adequately precise demographic subgroup estimates at the national level without needing to oversample specially targeted demographics, as was required in the past. The achieved sample size, or completed interviews, for the 2018 survey was 67,791 individuals. A coordinated sample design was developed for the 2014 through 2017 NSDUHs. A large reserve sample of area clusters or segments was selected at the time the 2014 through 2017 NSDUH sample was selected. This reserve sample is being used to field the 2018 through 2022 NSDUHs. Thus, the 2018 through 2022 NSDUH designs simply continue the coordinated design. The coordinated design facilitates a 50 percent overlap in third-stage units (area segments [see below]) between each 2 successive years from 2014 through 2022.10 This design was intended to increase the precision of estimates in year-to-year trend analyses because of the expected positive correlation resulting from the overlapping sample between successive survey years. The 2018 design allows for computation of estimates by state in all 50 states plus the District of Columbia. States may therefore be viewed as the first level of stratification and as a reporting variable. Compared with previous sample designs, the 2014 through 2022 sample design moves from two to essentially five state sample size groups (including Hawaii with the remaining states and the District of Columbia). The 2014 through 2022 surveys have a sample designed to yield 4,560 completed interviews in California; 3,300 completed interviews each in Florida, New York, and Texas; 2,400 completed interviews each in Illinois, Michigan, Ohio, and Pennsylvania; 1,500 completed interviews each in Georgia, New Jersey, North Carolina, and Virginia; 967 completed interviews in Hawaii; and 960 completed interviews in each of the remaining 37 states and the District of Columbia—for a total national target sample size of 67,507. The sample is selected from 6,000 area segments that vary in size according to state. The change in the state sample allocation in 2014 was driven by the need to increase the sample in the original 43 small states (to improve the precision of state and substate estimates in these states) while moving closer to a proportional allocation in the larger states.
Weight: 
The estimates yielded by NSDUH are based on sample survey data rather than on complete data for the entire population. This means that the data must be weighted to obtain unbiased estimates for survey outcomes in the population represented by the 2018 NSDUH. The "final analysis weight" of the ith respondent, say wi, can be interpreted as the number of sampling units in the NSDUH target population represented by the ith respondent. The sum of the weights over all respondents is used to estimate the size of the total target population, where the summation is over all respondents in the 2018 NSDUH. Similar to the 2017 NSDUH, three sets of analysis weights at the person level, questionnaire dwelling unit (QDU) level, and person pair level were developed for the 2018 NSDUH. The person-level, QDU-level, and person pair-level analysis weights shared the same first 11 weight components at the screening dwelling unit (SDU) level. In addition to the 11 common weight components, QDU-level and person pair-level analysis weights had several specific weight components, and the final weights are the product of all of the weight components. As in the 2017 NSDUH, all of the adults in the 2018 NSDUH sample received the WHODAS questions. Therefore, there was no need to have a separate adult mental health weight in the 2018 NSDUH because the person-level analysis weight could be used to produce the adult mental health estimates. The person-level analysis weights (ANALWT_C) are the product of 16 weight components from the analytic file, and two additional weight calibration adjustments done for the public use file. Each weight component accounts for either a selection probability at a selection stage or an adjustment factor adjusting for nonresponse, coverage, or extreme weights. The sum of the weight over all respondents on the data file represents an estimate of the total number of individuals in the target population. In view of the use of weights as expansion factors in forming estimates, the weight can be interpreted as the total number of individuals in the target population that each record on the file represents. For variance estimation, suitable software, such as SUDAAN®, should be used to take the sample design into account. Similar to the 2017 NSDUH, the 2018 NSDUH used 2010 census-based population estimates in the poststratification adjustment.
Response rates: 
  • The fieldwork for the 2018 NSDUH was directed by RTI staff members. RTI maintained a field staff of approximately 650 FIs to collect the data.

    A total final sample of 67,791 interviews was obtained for the 2018 survey. Strategies for ensuring high rates of participation resulted in a weighted screening response rate of 73.30 percent and a weighted interview response rate for the NSDUH of 66.56 percent; the overall response rate was 48.79 percent for people aged 12 or older.

    Throughout the course of the study, respondent anonymity and the privacy of responses were protected by separating identifying information from survey responses. Respondents were assured that their identities and responses would be handled in strict compliance with federal law. As discussed above, the questionnaire itself and the interviewing procedures were designed to enhance the privacy of responses, especially during segments of the interview in which questions of a sensitive nature were posed. Answers to sensitive questions were gathered using ACASI. During the ACASI portions of the interview, respondents listened to prerecorded questions through headphones and entered their responses directly into a NSDUH laptop computer without FIs knowing how they were answering. At the conclusion of the ACASI section, the interview returned to the CAPI mode with the FI asking the respondent questions and entering the responses into the laptop. Respondents who completed a full interview were each given $30 in cash as a token of appreciation for their time.