Predictors and Time Course of Response Among Panic Disorder Patients Treated With Cognitive-Behavioral Therapy

Objective: Cognitive-behavioral therapy (CBT) is well documented as an efficacious treatment for panic disorder. We provided open CBT treatment to patients who subsequently participated in a maintenance treatment study. This article reports on predictors and trajectory of response in 381 participants who completed treatment at 4 sites.

Method: Participants who met criteria for panic disorder with or without agoraphobia (N = 381) completed assessment and entered treatment. Of these, 256 completed 11 sessions of CBT delivered by trained and supervised research therapists. Raters trained to reliability obtained demographic data and administered structured diagnostic interviews and the Hamilton Rating Scales for Depression and Anxiety and the Panic Disorder Severity Scale (PDSS) measures at baseline and posttreatment. We obtained self-report (SR) measures of anxiety sensitivity and adult separation anxiety at baseline and posttreatment and PDSS-SR ratings weekly. The study was conducted between November 1999 and July 2002.

Results: Treatment response rate was 65.6% for completers and 44.1% for the intent-to-treat sample. Greater severity of panic disorder and lower levels of adult separation anxiety predicted response. Beginning at week 4, responders showed greater mean decreases in PDSS scores than nonresponders and maintained the advantage throughout the treatment. By week 6, 76% of responders, compared to 36% of nonresponders, recorded PDSS scores at least 40% below baseline on 2 consecutive weeks (odds ratio = 5.42, 95% CI = 3.10 to 9.48).

Conclusion: These results suggest that CBT is just as effective for more severe panic disorder patients as it is for those with less severe panic disorder, regardless of other comorbid disorders, including agoraphobia. However, patients experiencing adult separation anxiety disorder are less likely to respond. Our results further inform clinicians that many people who will respond to 11 weeks of treatment will have done so by the middle of the treatment.