Utility of lead-in period in cocaine dependence pharmacotherapy trials.

We examined whether drug use behaviors during a 2-week lead-in for a pharmacotherapy trial were predictive of retention in treatment and of the level of cocaine use during the subsequent 12 weeks of treatment. Fifty cocaine dependent patients were grouped based on: (1) principal route of cocaine administration: intranasal versus smoking, and (2) level of cocaine use during the 2-week lead-in: high versus low. Results indicate that level of cocaine use during the 2-week lead-in was a significant predictor of cocaine use during the subsequent 12 weeks of treatment. Patients with reported higher level of use during the lead-in period were more likely to continue using cocaine during the treatment. Patients who used smoking as their primary route of cocaine use were more likely to drop out early in the treatment. Findings of this study suggest that route and level of cocaine use during lead-in be used as a covariate in models testing treatment effect.