Subtyping panic disorder by major depression and avoidance behaviour and the response to active treatment.

In order to establish the clinical validity of currently used ways of subtyping panic disorder the predictive power of associated current avoidance behaviour and (secondary) major depression for the response to active treatment (alprazolam, imipramine) was tested. The analysis was based on the data from the Cross-National-Collaborative-Panic-Study. Limited support for validity evidenced by predicting drug response was found for grading panic disorder by the severity of avoidance behaviour; patients with panic attacks and agoraphobia are more responsive to imipramine (compared with alprazolam) when using the reduction of the total number of panic attacks (or of spontaneous panic attacks) as the outcome criterion; patients without any avoidance behaviour did better with alprazolam (compared with imipramine).