Longer term outcome of cognitive-behavioural and psychodynamic psychotherapy in routine mental health care: randomised controlled trial.

We investigated the comparative effectiveness of cognitive-behavioural (CBT) and psychodynamic therapy (PDT) under clinically representative conditions as a subtrial of a prior study (Watzke et al., 2010, BJP). A consecutive sample of 147 patients with common mental disorders was randomised to either CBT or PDT in routine mental health care. In a primary per-protocol analysis patients randomised to CBT had a significantly better longer term outcome in the primary outcome symptom severity (General Severity Index of the SCL-14; p=.001; partial η(2)=0.073) as well as in health related quality of life (Mental Component Summary of the SF-8; p=.013; partial η(2)=.041) and concerning interpersonal issues (Inventory of Interpersonal Problems, IIP-C; p=.001; partial η(2)=.070) 6 months after treatment than patients randomised to PDT. These results could be confirmed in intention-to-treat analyses (n=180) suggesting that there was no substantial attrition bias due to drop outs at the follow-up assessment. Thus, the so called equivalence outcome paradox was not replicated in this study.