Improvements in Depression Outcomes Following a Digital Cognitive Behavioral Therapy Intervention in a Polychronic Population: Retrospective Study (Preprint)

Abstract

BACKGROUND Digital mental health interventions have shown promise in reducing barriers to effective care for depression. OBJECTIVE We aimed to examine the effectiveness of a 12-week, therapist supported, app-based cognitive behavioral therapy program in improving symptoms of depression and anxiety in an adult population with a heavy burden of chronic physical disease including obesity and type 2 diabetes. METHODS A total of 1512 participants with at least moderate depression were enrolled. The treatment cohort consisted of 831 participants who completed a follow-up assessment. The program included structured lessons and tools (ie, exercises and practices) and offered one-on-one weekly video counseling sessions with a licensed therapist for 12 weeks and monthly sessions thereafter. The clinically validated Patient Health Questionnaire (PHQ-8) and Generalized Anxiety Disorder Scale (GAD-7) were used to assess depression and anxiety, respectively. Linear mixed-effects modeling was employed to examine changes in depression and anxiety over time. Given correlation among various measures of program usage, a composite variable for depth of usage was used to analyze the correlation between usage and changes in depressive symptoms. Bodyweight changes from baseline were assessed primarily with digitally connected scales. RESULTS 74.5% (619/831) of participants in the treatment cohort showed a clinically significant reduction in depressive symptom severity in 12 weeks where follow-up PHQ-8 scores had shifted downwards by at least one diagnostic category. 67.5% (561/831) showed a reliable improvement in PHQ-8 scores as measured by the reliable change index. There was an average reduction of 5.9 points (SD=5.2, P<0.001) between baseline and follow-up. Greater program usage was correlated with greater likelihood of reliable improvement in depressive symptoms (OR=1.3, 95% CI: 1.1–1.5, P=0.002). Exploratory analysis of bodyweight changes with a multilevel, mixed-effect model suggested that reliable improvement in depressive symptoms at follow-up was associated with significantly greater weight loss at 9 months (B=–1.11, P=0.002). CONCLUSIONS The results provide further support that digital interventions can support clinically meaningful improvements in depression. Some form of synergy in treatment of comorbid depression and obesity or diabetes could be studied in future research. The study was limited by post-intervention participant attrition as well as the retrospective observational study design.