Outcome of Psychoanalytic and Cognitive-Behavioural Long-Term Therapy with Chronically Depressed Patients: A Controlled Trial with Preferential and Randomized Allocation

Objective: For chronic depression, the effectiveness of brief psychotherapy has been limited. This study is the first comparing the effectiveness of long-term cognitive-behavioural therapy (CBT) and long-term psychoanalytic therapy (PAT) of chronically depressed patients and the effects of preferential or randomized allocation. Methods: A total of 252 adults met the inclusion criteria (aged 21-60 years, major depression, dysthymia, double depression for at least 24 months, Quick Inventory of Depressive Symptoms [QIDS] >9, Beck Depression Inventory II [BDI] >17, informed consent, not meeting exclusion criteria). Main outcome measures were depression self-rating (BDI) and rating (clinician-rated QIDS [QIDS-C]) by independent, treatment-blinded clinicians. Full remission rates (BDI <= 12, QIDS-C <= 5) were calculated. An independent center for data management and biostatistics analyzed the treatment effects and differences using linear mixed models (multilevel models and hierarchical models). Results: The average BDI declined from 32.1 points by 12.1 points over the first year and 17.2 points over 3 years. BDI overall mean effect sizes increased from d = 1.17 after 1 year to d = 1.83 after 3 years. BDI remission rates increased from 34% after 1 year to 45% after 3 years. QIDS-C overall effect sizes increased from d = 1.56 to d = 2.08, and remission rates rose from 39% after 1 year to 61% after 3 years. We found no significant differences between PAT and CBT or between preferential and randomized allocation. Conclusions: Psychoanalytic as well as cognitive-behavioural long-term treatments lead to significant and sustained improvements of depressive symptoms of chronically depressed patients exceeding effect sizes of other international outcome studies.