Data were obtained from the 2002–2014 National Survey on Drug Use and Health (NSDUH). NSDUH is directed by the Substance Abuse and Mental Health Services Administration and contracted through RTI, International. The survey is conducted annually and measures substance use patterns in the U.S. civilian, noninstitutionalized, domiciled population aged 12 and older. NSDUH utilizes a 50-state design with an independent multistage area probability sample for each state and the District of Columbia. Informed consent is obtained prior to participation. RTI fieldworkers interview participants; questions about potentially sensitive behaviors, including drug use and illegal activities, are administered via audio-computer-assisted self-interview to maximize confidentiality. Detailed information about survey methodology is available elsewhere (28). Data collection procedures were approved by the Institutional Review Board at RTI. Public use NSDUH files for the time period of interest were obtained from the Interuniversity Consortium for Social and Political Research (29).
