Panic and avoidance in agoraphobia. Application of path analysis to treatment studies.

We explored a causal sequence between panic and avoidance to provide recommendations for psychotherapy, pharmacotherapy, and their combination in treating agoraphobia. We produced a two-way [( imipramine hydrochloride vs placebo] by [office-based behavioral therapy vs in vivo exposure]) design by amalgamating two studies. We assessed agoraphobic patients for panic and avoidance at these time points: baseline (week 0), midcourse (week 13), and termination (week 26). The causal sequence model was tested by path analysis. Imipramine was superior to placebo in lowering panic and avoidance at both postbaseline time points. Exposure was superior to office-based treatment in lowering avoidance only at week 13. Exposure appeared to produce quicker improvement of avoidance than office-based therapy, but relapse occurred if this improvement was not supported by medication. Exposure did not benefit panic. We believe patients should be informed that imipramine is superior to exposure in inducing a panic-free state. Exposure without imipramine is of benefit only in reducing avoidance, but adding imipramine to exposure is necessary for panic control and substantially improves exposure and exposure maintenance.