Prognostic indices with brief and standard CBT for panic disorder: II. Moderators of outcome

Background. Despite the growth of reduced therapist-contact cognitive behavioural therapy (CBT) programmes, there have been few systematic attempts to determine prescriptive indicators for such programmes vis-à-vis more standard forms of CBT delivery. The present study aimed to address this in relation to brief (6-week) and standard (12-week) therapist-directed CBT for panic disorder (PD) with and without agoraphobia. Higher baseline levels of severity and associated disability/co-morbidity were hypothesized to moderate treatment effects, in favour of the 12-week programme. Method. Analyses were based on outcome data from two out of three treatment groups (n=72) from a recent trial of three forms of CBT delivery for PD. The dependent variables were a continuous composite panic/anxiety score and a measure of clinical significance. Treatment×predictor interactions were examined using multiple and logistic regression analyses. Results. As hypothesized, higher baseline severity, disability or co-morbidity as indexed by strength of dysfunctional agoraphobic cognitions; duration of current episode of PD; self-ratings of panic severity; and the 36-item Short Form Health Survey (SF-36) (Mental component) score were all found to predict poorer outcome with brief CBT. A similar trend was apparent in relation to baseline level of depression. With high and low end-state functioning as the outcome measure, however, only the treatment×agoraphobic cognitions interaction was found to be significant. Conclusions. While there was no evidence that the above variables necessarily contraindicate the use of brief CBT, they were nevertheless associated with greater overall levels of post-treatment improvement with the 12-week approach.