Prescription Opioid Use, Misuse, and Use Disorders in U.S. Adults: 2015 National Survey on Drug Use and Health

The United States is experiencing an epidemic of prescription opioid misuse, with prescription opioid overdose deaths more than quadrupling between 1999 and 2015 (14). Misuse is defined as use of a psychotropic medication without a prescription; for a reason other than as directed by a physician; or in greater amounts, more often, or longer than prescribed. The potential for misuse complicates prescription of opioids (5, 6). Several studies based on local data (711) or national samples of high school seniors (12, 13) have examined motivations for medication misuse. However, an examination of the prevalence of prescription opioid use, misuse, and use disorders and motivations for misuse in the U.S. adult population has been lacking. Such data could inform efforts to reduce prescription opioid misuse and related morbidity and mortality. Based on a nationally representative sample of U.S. adults, this study examined the 12-month prevalence of prescription opioid use by sociodemographic characteristics, health conditions, and behavioral health status; the prevalence of misuse and use disorders among prescription opioid users by sociodemographic characteristics, health conditions, and behavioral health status; motivations for misuse; and sources of prescription opioids among adults with misuse and use disorders. Methods Survey Methods and Study Population The 2015 National Survey on Drug Use and Health (NSDUH) was a face-to-face household interview survey conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA). The NSDUH used a stratified, multistage area probability sample that was designed to be representative of the nation as a whole as well as each of the 50 states and the District of Columbia. Under a stratified design, with states serving as the primary strata and state sampling regions serving as the secondary strata, census tracts, census block groups, segments within census block groups, and dwelling units within segments were selected using probability-proportional-to-size sampling. After dwelling units were selected, an interviewer visited each unit to obtain a roster of all persons residing there. The roster information obtained from an eligible member of the dwelling unit was used to select 0 to 2 people for the survey. Data collection for NSDUH was approved by the Institutional Review Board at RTI International. Data were collected by interviewers in personal visits to households and noninstitutional group quarters. Each participant provided verbal informed consent. The interview lasted about an hour, and each respondent received $30 in cash after completion (14). The NSDUH collected nationally representative data on prescription opioid use, misuse, and use disorders and motivations for misuse among the U.S. civilian, noninstitutionalized population aged 12 years or older (14). Additional details about the NSDUH survey methods and questionnaire are available at SAMHSA's Web site (14). The NSDUH collected data using audio computer-assisted self-interviewing, in which respondents read or listened to the questions on headphones and then entered their answers directly into a laptop computer. This interview technique is designed for accurate reporting of information by providing respondents with a private, confidential way to record answers to sensitive questions. The NSDUH also used computer-assisted personal interviewing, in which interviewers read less sensitive questions to respondents and entered answers into the laptop computer. In 2015, the NSDUH screening process (in which an interviewer visited each selected dwelling unit to obtain a roster of all persons residing there) was completed at 132210 addresses, and the weighted screening response rate was 79.7%, which was not specific to age groups (14). The weighted interview response rate was 68.4% for adults, based on the definitions of the American Association for Public Opinion Research (15). A total of 72600 eligible persons aged 18 years or older were selected for the 2015 NSDUH, and 51200 completed the survey interview. Measures of Main Outcomes and Patient Characteristics The 2015 NSDUH asked about lifetime and past-year use and misuse of prescription opioids. The NSDUH defined prescription opioid misuse as in any way that a doctor did not direct you to use them, including 1) use without a prescription of your own; 2) use in greater amounts, more often, or longer than you were told to take them; or 3) use in any other way a doctor did not direct you to use them (16). Past-year prescription opioid use disorder was defined on the basis of the 11 diagnostic criteria for prescription opioid dependence or abuse specified in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), including withdrawal; tolerance; use in dangerous situations; trouble with the law; and interference with major obligations at work, school, or home (17). For respondents who reported prescription opioid misuse in the past year, NSDUH asked about the main motivation for the most recent episode with multiple-choice questions that offered the following options: to relieve physical pain, to relax or relieve tension, to experiment or see what the drug was like, to feel good or get high, to help with sleep, to help with feelings or emotions, to increase or decrease the effects of other drugs, because the respondent was hooked or had to have it, or other reason (16). The source of prescription opioids for the most recent episode of misuse was assessed with a multiple-choice question that offered the following options: obtained from a friend or relative for free; prescribed by a physician; stolen from a friend or relative; bought from a friend or relative; bought from a drug dealer or stranger; or stolen from a physician's office, clinic, or pharmacy. If respondents reported that they obtained the prescription opioids from a friend or relative for free, NSDUH asked them where the friend or relative had obtained the opioids. In addition to sociodemographic characteristics (age, sex, race/ethnicity, educational attainment, employment status, family income, marital status, health insurance, metropolitan statistical area, and census region), NSDUH asked respondents about lifetime and past-year use of tobacco, alcohol, cannabis, cocaine, heroin, hallucinogens, and inhalants as well as lifetime and past-year use and misuse of prescription sedatives, tranquilizers, and stimulants. Using survey items assessing DSM-IV diagnostic criteria, the NSDUH estimated prevalence in the past 12 months of major depressive episode and substance use disorders (alcohol, cannabis, cocaine, heroin, hallucinogens, inhalants, prescription tranquilizers or sedatives, and prescription stimulants) in addition to prescription opioid use disorders (17). Nicotine dependence among cigarette smokers was assessed using the Nicotine Dependence Syndrome Scale (18). These measures of substance use and use disorders have demonstrated good validity and reliability (1921). For example, the 2006 NSDUH Reliability Study reported that the coefficient (a standard measure of testretest agreement) was 0.73 for prescription opioid misuse and 0.62 for illicit drug use disorders, suggesting good to excellent reliability (21). Furthermore, a clinical validation study reported sensitivity of 0.85 and specificity of 0.75 for illicit drug use disorders (including prescription opioid use disorder) (20). Finally, the survey asked about medical diagnoses received from a physician or other health care professional (hypertension, heart disease, diabetes mellitus, chronic obstructive pulmonary disease, asthma, cancer, HIV/AIDS, hepatitis B or C, cirrhosis, and kidney disease), respondents' self-rated health, and the number of emergency department visits in the prior year. Among the 2015 NSDUH adult participants, item response rates were high (for example, >99% for the prescription opioid misuse and use disorder variables). Furthermore, missing values are imputed in NSDUH using predictive mean neighborhoods (22, 23), a combination of a model-assisted imputation method and a random nearest-neighbor hot-deck procedure. For prescription opioid use, misuse, and use disorders (the main variables of this study), a modified version of predictive mean neighborhoods was used to cycle through a group of variables being imputed as a set (23). Statistical Analysis We estimated the national 12-month prevalence of prescription opioid use overall and by sociodemographic, health, and behavioral health characteristics. Next, among adults with prescription opioid use in the past 12 months, we estimated the national 12-month prevalence of prescription opioid misuse and use disorders overall and by sociodemographic, health, and behavioral health characteristics. Finally, we assessed the main motivations and the sources of prescription opioids for the most recent episode of misuse. We used SUDAAN software (RTI International) (24) to account for the complex sample design and sample weights of NSDUH. The NSDUH weighting procedures adjusted for nonresponse through direct adjustments as well as an indirect adjustment via poststratification (25). Institutional Review Board Approval The NSDUH data collection protocol was approved by the U.S. Office of Management and Budget and the Institutional Review Board at RTI International. Role of the Funding Source The funding sources supported the authors, who were responsible for preparation, review, and approval of the manuscript and the decision to submit the manuscript for publication. The funding sources had no role in the design and conduct of the study, analysis and interpretation of the data, preparation and review of the manuscript, or the decision to submit the manuscript for publication. The funding sources reviewed and approved the manuscript. Results National Prevalence of Prescription Opioid Use, Misuse, and Use Disorders On the basis of the 51200 adult respo