The impact of comorbid cluster B traits and personality disorders on depression treatment outcome: a systematic review and meta-analysis

There are opposing opinions and evidence about the effect of comorbid personality disorders (PDs) on the treatment outcome for depression. Here a systematic search was conducted to identify studies reporting on the effect of comorbid cluster B PDs on depression treatment outcomes. Medline, PsycINFO, Web of Science, Embase and Cochrane Library databases were searched in March 2024, yielding 61 reports of which 25 had sufficient data to be included in the meta-analysis. The overall effect of poor outcome in patients with comorbid cluster B PDs compared with those without PDs was 2.27 (95% confidence interval 1.63–3.15, P < 0.00001, pooled n = 5,419). The presence of concurrent cluster B PDs is associated with more than double the odds of nonresponse to treatments for depression compared with patients with depression without comorbid PDs. This synthesis highlights the prognostic value of comorbid cluster B PDs in depressive disorders and a need for devising new treatment approaches to target this complex patient population. In a systematic review and meta-analysis, the authors find that individuals with a concurrent cluster B personality disorder diagnosis are 2.27 times more likely not to respond to treatment for depression than patients without personality disorders, suggesting the need for more targeted approaches for patients with comorbid personality disorders.