What is the effect of homework engagement in group cognitive behavioral therapy for anxiety disorders and depression?

BACKGROUND: Homework is integral to cognitive behavioral therapy (CBT) treatment programs. Previous research has reported mostly positive findings regarding the effect of homework adherence on CBT outcomes, but only limited research has evaluated the effect in transdiagnostic CBT (tCBT).

METHODS: This secondary study used data from 164 patients with major depressive disorder, social phobia, agoraphobia, or panic disorder, randomized to 14 sessions of diagnosis-specific CBT (dCBT) in groups or group tCBT (Unified Protocol). The number of times patients engaged in homework assignments was measured with a single-item homework engagement assessment. We evaluated the effects of total mean homework engagement on symptom outcomes using the Hopkins Symptom Checklist at the end of therapy, and the effect of intervention arm and diagnosis on homework engagement across three periods with repeated measures analysis of variance. Finally, we used cross-lagged panel modeling (CLPM), with the inclusion of baseline covariates and interaction variables, to investigate whether homework engagement predicted next-session symptom severity as measured with the Overall Depression Severity and Impairment Scale and the Overall Anxiety Severity and Impairment Scale.

RESULTS: Patients' general homework engagement significantly affected their symptoms at end of treatment (F1,162: 3.944, p = 0.05), and had a significant cross-lagged effect on next-week symptoms (coefficient = - 0.23, se = 0.11, z = -2.16, p = 0.03, 95% CI [-0.44, - 0.02]). Initial analysis indicated that homework engagement was higher in dCBT than in the UP, and patients with depression in dCBT conditions were more engaged in homework assignments in the first period of therapy. However, these differences did not affect the overall treatment outcome in repeated measures or CLPM analyses.

DISCUSSION: This is the first study to examine the effects of homework engagement on symptoms in group UP and also adds to the limited literature using such methods to isolate the unique effects of treatment engagement on symptom outcomes. Future studies should confirm these results and investigate other relevant aspects of homework engagement, such as the quality of said engagement and process variables such as therapist factors, group cohesion, and negative effects of homework assignments.