Internet-delivered cognitive behavioral therapy for panic disorder with or without agoraphobia: a systematic review and meta-analysis.

The current systematic review and meta-analysis examined the efficacy and effectiveness of internet-delivered cognitive behavioral therapy (iCBT) on panic disorder and agoraphobia symptom severity. Twenty-seven studies were identified. Results from nine randomised controlled trials (RCTs) showed that iCBT outperformed waiting list and information controls for panic (g = 1.22) and agoraphobia (g = .91) symptoms, but the quality of RCTs varied and heterogeneity was high. Results from three RCTs suggested iCBT may have similar outcomes to face-to-face CBT in reducing panic and agoraphobia symptoms. Within-group effect sizes between baseline and post-treatment were large for panic (n = 29, g = 1.16) and medium for agoraphobia symptom severity (n = 18, g = .73). Subgroup analyses of within-group pre/post treatment effect sizes showed larger within-group effect sizes for efficacy studies (n = 15) compared to effectiveness studies (n = 14) for panic severity (g = 1.38 vs. g = .98) but not agoraphobia severity. There was no impact of program length, inclusion or arousal reduction techniques, or degree of clinician support. Within-group effects of iCBT suggest the reduction in panic and agoraphobia symptom severity is maintained at 3-6 month follow-up (n = 12).