Abstinence at intake for marijuana dependence treatment predicts response

Abstinence prior to entering treatment is common among individuals seeking substance abuse treatment. The current study examined the relationship between abstinence at a pretreatment intake assessment and treatment response during outpatient treatment for marijuana dependence. At the intake assessment, 142 marijuana-dependent individuals completed past 30 day calendars of daily drug use. Forty-four (31%) participants were pretreatment abstainers, as defined by reports of one or more consecutive days of marijuana abstinence prior to the day of the intake assessment. Non-abstainers (69%) reported marijuana use the day prior or the day of the assessment. Pretreatment abstainers were more likely to enter treatment (P < 0.05) and showed better treatment response than non-abstainers. Abstainers provided 50% more marijuana-negative urine screens during treatment (P < 0.05), and more than three times as many abstainers reported no marijuana use (P < 0.01). The groups did not differ on treatment completion. Marijuana abstinence at the time of initial clinic contact appears to be a strong predictor of success during treatment. Pretreatment abstinence may prove useful as a pretreatment matching strategy that could improve outcomes and cost-effectiveness. Clinical trials might consider including pretreatment abstinence status as a stratification variable during participant assignment or as a covariate in outcome analyses.