The cocaine use and related behaviors section of the SSADDA contains 25 questions on age of onset, frequency, and intensity of cocaine use; route of cocaine administration; occurrence of psychosocial and medical consequences of cocaine use; attempts to quit cocaine use; and cocaine abuse treatment sought and received, resulting in 160 variables. In a previous study, in which we used a subset of the present sample, we identified 68 key questions (see Supplementary Tables SI and SII) in this section that performed well for subtyping cocaine use and related behaviors [Kranzler et al., 2008]. Those features were based on their clinical utility as discriminators of cocaine use behavior subtypes and were used here to generate subtypes of cocaine use and related behaviors. Demographics and other substance use and psychiatric variables obtained from the SSADDA interview and estimated heritability served to test the validity of the clusters.
