Predictors of marijuana treatment outcomes: the role of self-efficacy.

This study tested the ability of sets of demographic, socioeconomic, marijuana use/abuse, psychological distress, and self-efficacy variables to predict posttreatment indices of marijuana intake and problems related to use. Subjects were 167 adults who participated in one of two outpatient treatments for marijuana dependence and completed the 3-, 6-, and 12-month posttreatment follow-ups. Only pretreatment marijuana quantity-frequency of intake and self-efficacy variables made significant and consistent contributions to the regression equations predicting posttreatment frequency of use. In contrast, socioeconomic and severity of abuse indicators predicted posttreatment marijuana-related problems. Contrary to social cognitive theory (Bandura, 1986), there was no evidence that self-efficacy mediated the effects of other predictors. Results are discussed in terms of the specificity of predictor-outcome relationships and the need for improvements in self-efficacy measurement.