Effectiveness, response, and dropout of dialectical behavior therapy for borderline personality disorder in an inpatient setting.

To examine the effectiveness of dialectical behavior therapy for inpatients with borderline personality disorder (BPD), small sample sizes and, predominantly, tests of statistical significance have been used so far. We studied 1423 consecutively admitted individuals with BPD, who were seeking a 3-month inpatient treatment. They completed the Borderline Symptom List (BSL) as the main outcome measure, and other self-rating measures at pre- and post-treatment. Therapy outcome was defined in three ways: effect size (ES), response based on the reliable change index, and remission compared to the general population symptom level. Non-parametric conditional inference trees were used to predict dropouts. In the pre-post comparison of the BSL, the ES was 0.54 (95% CI: 0.49-0.59). The response rate was 45%; 31% remained unchanged, and 11% deteriorated. Approximately 15% showed a symptom level equivalent to that of the general population. A further 10% of participants dropped out. A predictive impact on dropout was demonstrated by substance use disorders and a younger age at pre-treatment. In future research, follow-up assessments should be conducted to investigate the extent to which response and remission rates at post-treatment remain stable over time. A consistent definition of response appears to be essential for cross-study and cross-methodological comparisons.