Abstract
Although the alliance-outcome correlation is well established, no published studies to date have separated between therapists' and patients' contributions while controlling for early symptom change. In this study, we examined therapist effects in two trials of CBT for panic disorder with agoraphobia (PDA) and the impact of therapists' and patients' contribution to the alliance on outcome and attrition in one trial. Alliance ratings were obtained from patients and therapists early and late in treatment (n = 133). Data were analyzed using multi-level modeling controlling for early symptom change. No therapist effects were found. The patients' contribution to the alliance predicted outcome (in both panic severity and anxiety sensitivity) and attrition. The therapists' contribution to the alliance predicted attrition but not outcome. Results suggest that the patient's contribution to the alliance plays an important role in CBT for PDA and that including common factors into research on CBT may help elucidate treatment processes.