Participants completed the Composite International Diagnostic Interview – Substance Abuse Module (CIDI-SAM), a valid and reliable structured interview which provides information on DSM-IV symptoms and diagnoses of abuse and dependence 26–28. The present study uses lifetime symptoms and diagnoses based on information collected in the CIDI-SAM regarding the frequency, onset, and temporal clustering of DSM-IV substance use symptoms. Interviews were conducted by trained lay interviewers. Participants gave written informed assent/consent and were paid a nominal fee for participation. The research was approved by the Institutional Review Boards for each participating campus of the University of Colorado.
