Internet-delivered exposure therapy versus internet-delivered cognitive behavioral therapy for panic disorder: A pilot randomized controlled trial

•Compared internet exposure therapy to internet cognitive behavioral therapy.•Adherence was strong (81 % completion rate) and both interventions were acceptable.•Significant reduction in panic severity and functional impairment for both groups.•No significant difference between groups; effects maintained at six-month follow-up.•A fully powered comparison study is needed. To compare the efficacy and acceptability of internet-delivered exposure therapy for panic disorder, to multi-component internet-delivered cognitive behavioral therapy (iCBT) that included controlled breathing, cognitive restructuring and exposure. Participants with panic disorder, with or without agoraphobia, were randomized to internet-delivered exposure therapy (n = 35) or iCBT (n = 34). Both programs were clinician guided, with six lessons delivered over eight weeks. Outcomes included panic disorder and agoraphobia symptom severity, as well as depression symptom severity, functional impairment and days out of role. Participants in both conditions displayed a large reduction in panic disorder symptom severity (ds >1.30) from pre- to post-treatment. Participants in both conditions displayed medium to large reduction in agoraphobia and depression symptom severity, functional impairment and days out of role. Effects were maintained at three- and six-month follow-up. There was no significant difference between the interventions in clinical outcomes, adherence or treatment satisfaction. Internet-delivered exposure therapy appeared to be as acceptable and efficacious as more established iCBT, despite including less strategies. However, a fully powered replication is now needed to compare the two approaches.