Strengths include the rigorous conduct of the original trial (standardized assessments, comprehensive research staff training, protocol monitoring, regulatory control); geographic diversity (from 11 cities across the nation); and inclusion of all opioid-dependent participants from study intake in the analysis, thus making the sample more heterogeneous than that found at a single site. All participants were assessed for substance-specific SUDs using the same instrument, allowing for comparisons of all dependence criteria across various substances. Such comparisons provide vital information regarding whether a similar set of questions can apply to alcohol and various drugs, as prior research has focused on two dependence-related questions and combined alcohol and drug use into a single question (Brown et al., 2001). Another strength is the assessment of the withdrawal criterion for cannabis, hallucinogen, and inhalant use disorders, permitting comparison of this criterion with others. Withdrawal is not considered present for these SUDs in the DSM-IV (APA, 2000), but data are needed to evaluate its inclusion in DSM-5 with regards to prevalence and screening efforts.
