Adolescents were asked whether they had ever used a list of illicit drugs “even once.” Respondents were asked about (1) “marijuana or hashish”; (2) “cocaine in any form, including powder, crack, free base, coca leaves, or paste”; (3) “tranquilizers, stimulants, painkillers, or other prescription drugs either without the recommendation of a health professional, or for any reason other than a health professional said you should use them”; and (4) “heroin, opium, glue, LSD, peyote, or any other drug.”45,50 We created a dichotomous variable for polydrug use by combining affirmative responses from the above list, and assigning a “yes” value if participants endorsed use of greater than one drug type.
