Of 60 individuals randomized to CBT, 57 initiated treatment, 54 completed more than one treatment session and 50 had homework assigned. Twenty-seven of the 50 participants randomized to CBT who were assigned homework completed treatment; of the 23 participants who did not begin or who dropped out of treatment, 19 were successfully tracked and interviewed for the posttreatment assessment. Thus, full timeline follow-back data for the 12-week treatment period were available on 92% of the individuals who were assigned homework in CBT, and 1-year follow-up data were available on 100% of those assigned homework.
Of the 50 participants who were assigned homework, 43 attempted or completed homework and 26 of those completed homework once or more during treatment, on the basis of the therapists' weekly session reports. Homework was assigned by therapists in 72% of all sessions, was attempted or completed by participants in 48% of sessions where it was assigned, and was fully completed in 24% of the sessions in which it had been assigned. and present participant demographic and baseline characteristics by homework completion, treated as a categorical variable. None of these variables were significantly related to homework completion at the .05 level.
Demographic and Baseline Characteristics by Level of Homework Completion
Baseline Psychosocial Functioning and Substance Use Variables by Level of Homework Completion
There were no significant differences across therapists in the mean number of sessions in which homework was assigned by the therapists, F(4, 38) = 0.73, p = .58; the percentage of their participants who completed homework, F(4, 38) = 2.10, p = .72; or in their overall percentage of sessions in which homework was attempted or completed, F(4, 38) = 0.65, p = .63. The therapists' reports of whether they had assigned homework for the next session closely matched the independent raters' ratings regarding whether homework had been assigned in that session, F(1, 271) = 43.20, p < .001. Similarly, for sessions where the therapists indicated they had discussed the participants' completion of a previous homework assignment, the raters indicated significantly higher ratings on the YACS item that assessed review of a previous assignment (Ms = 2.6 vs. 1.5, respectively), F(1, 271) = 52.20, p < .001. There were also strong associations between participants' compliance with homework assignments and ratings of the therapists' overall CBT adherence and skill. That is, compared with session in which homework was not done, there were significantly higher ratings mean ratings of CBT adherence (2.7 vs. 2.2), F(1, 270) = 20.10, p < .001, and skill (4.5 vs. 4.2), F(1, 264) = 8.50, p < .001, for those sessions in which homework had been completed or attempted, as measured by the six-item CBT Scale of the YACS. As shown in , homework completion was significantly related to retention, as measured by the number of treatment sessions completed. However, the extent to which participants completed assignments was not strongly associated with other markers of compliance such as total number of weeks in treatment or medication compliance. Level of homework completion was not significantly related to the working alliance from the participants' perspective but was associated with the alliance from the therapists' perspective.
Treatment Compliance and Working Alliance by Level of Homework Completion
Acquisition of coping skills was assessed before and after treatment by independent ratings of quality and type of coping responses on the CRRT role-playing task. As shown in , there were significant Group X Time interactions for a number of CRRT dimensions. These interactions suggest that there were greater increases across time in the quality of participants' coping responses and greater reductions in the number of situations in which the participants indicated they were likely to use cocaine, with post hoc Tukey's tests indicating that those completing homework had significantly better responses than those who did not do homework or those who only attempted homework. Similarly, self-reported confidence in a range of high-risk situations, as measured by the CUI, suggested that participants who completed homework reported significantly greater increases in confidence than those who did not do or only attempted homework.
Changes in Coping Skills and Confidence in Responding to High-Risk Situations by Level of Homework Completion
There were also significant relationships between homework completion and cocaine use outcomes. As shown in , participants who completed homework had a significantly higher percentage of days abstinent from cocaine during treatment and tended to have a higher percentage of cocaine-free urine specimens (p = .09) than those who did not do or who only attempted homework. Similarly, the participants' longest period of consecutive abstinence during the 12-week treatment period was strongly associated with their level of homework completion.
Cocaine Use Outcomes by Level of Homework Completion
Homework completion was strongly related to outcome during the one-year follow-up. As shown in , which provides estimates from random regression analyses evaluating frequency of cocaine use across the 1-year follow-up by level of homework completion, participants who completed or attempted homework during treatment used cocaine significantly less frequently during follow-up than those who did not do homework (Homework X Time z = 2.04, p = .04). Moreover, the relationship between doing any homework and long-term outcome remained significant even after including number of sessions completed in the model as a covariate (Homework X Time z = 2.1, p = .04; covariate z = 2.6, p = .01).
Estimates (based on random regression analyses) of cocaine use during 1-year follow-up by level of homework completion and by month.