Randomized Study of Cognitive-Behavioral Therapy vs Imipramine and Their Combination for Panic Disorder

PROTOCOL OUTLINE: This is a randomized, double-blind, placebo-controlled study. Patients are randomized to receive one of five treatments: cognitive-behavioral therapy (CBT) alone, imipramine plus medical management (IMI), CBT plus IMI, pill placebo plus medical management (PLA), or CBT plus PLA.

Patients are seen by therapists for 11 sessions over 12 weeks (3 sessions during days 1-10 followed by 6 weekly sessions and 2 biweekly sessions). Each CBT session lasts approximately 1 hour, each IMI session lasts approximately 30 minutes, and patients in combined treatment see 2 therapists for a total of about 80 minutes. Oral IMI or placebo is taken daily.

Patients not responding to placebo or IMI after the initial 12 weeks are offered alternative treatment for up to 3 months or given a referral; responders continue to be treated monthly for the next 6 months. This is followed by a washout period of 6 months, after which patients receive final assessment. All therapy and assessment sessions are video- or audiotaped.

Patients are interviewed by an independent evaluator at the start of treatment and 3, 9, and 15 months later, and must keep a set of weekly self-monitoring forms. In addition, patients complete rating forms and questionnaires, and undergo carbon dioxide measurement at the start of treatment and 3, 9, and 15 months later.

At study conclusion, patients are told which medication they received and receive treatment recommendations.