Differential effectiveness of group, individual, and conjoint treatments: An archival analysis of OQ-45 change trajectories.

Objective: While empirically-supported treatment (EST) choices are continually expanding, choices regarding formats for delivery (individual only, group only, or conjoint [simultaneous individual & group]) are often determined by agency resources or clinician preference. Studies comparing individual and group formats have produced mixed results, while recent meta-analytic reviews support format equivalence.

Method: We employed a multilevel model to test for outcome differences using the OQ-45 on an outpatient archival data set of clients receiving individual-only (n = 11,764), group-only (n = 152) or conjoint (n = 1557).