Past-year heroin use was examined as a dichotomous variable. A dichotomous variable for past-year non-heroin illicit drug use was created as a composite of the following NSDUH variables: past-year use of hallucinogens, inhalants, or cocaine; or past-year non-medical use of sedatives, tranquilizers or stimulants. Given the relatively high prevalence of recreational cannabis use as well as recent changes in cannabis legalization in multiple states, cannabis use was not included in the variable.
