Within- and between-patients associations between self-efficacy, outcome expectation, and symptom change in cognitive behavioral therapy for generalized anxiety disorder.

Patients' self-efficacy and outcome expectation increased, whereas severity of their symptoms reduced during and after treatment. At the within-patient (WP) level, an increase in self-efficacy was associated with a decrease in worry and depressive symptoms, and an increase in outcome expectation was associated with a decrease in depressive symptoms. The between-patient (BP) effect, however, was contrary to the WP effect, that is, self-efficacy was positively correlated with worry and outcome expectation was positively correlated with depressive symptoms CONCLUSION: These results highlight the importance of disaggregating the WP variability from BP variability in psychotherapy process-outcome research as they exhibit different associations at the within- and between-patient levels. Clinical Trial Registration: ClinicalTrial.gov (NCT03079336).