Is Personalized Treatment Selection a Promising Avenue in BPD Research? A Meta-Regression Estimating Treatment Effect Heterogeneity in RCTs of BPD

Objective: Psychotherapy is the first-line treatment for borderline personality disorder (BPD) in evidence-based care. The effects are, on average, medium; however, nonresponse rates point to differential treatment effects. Personalized treatment selection has the potential to improve outcomes, but they depend on the heterogeneity of treatment effects (HTEs), which this article seeks to establish. Method: Using an extensive database of randomized controlled trials on psychotherapy for BPD, we determined a reliable estimate of this heterogeneity in treatment effects by (a) applying Bayesian variance ratio meta-analysis and (b) estimating the HTE. In total, 45 studies were included in our study. HTE was found for all psychological treatments, although with low degrees of certainty. Results: Across all psychological treatment and control group types, the estimate for the intercept was 0.10, indicating a 10% higher variance of endpoint values in the intervention groups after controlling for differences in posttreatment means. Conclusions: The results suggest that, while there might be sufficient heterogeneity in treatment effects, the estimates are uncertain, and future research is needed to gain more accurate boundaries for HTE. Personalizing psychological treatments for BPD by using treatment selection approaches could have positive effects, but the current evidence does not allow for a precise estimate of potential outcome improvement.