Background: Results from previous meta-analyses of the impact of comorbid personality disorders (PD's) on treatment outcomes for depressive disorder are contradictory and biased by methodological differences between included studies.
Aim: To investigate the impact of comorbid PD on the outcome of depression treatments, using only studies with controlled treatments and structured measurement instruments (PROSPERO, CRD42019120200).
Method: Studies were searched in PubMed, PsycINFO and Embase, and in reference lists of selected articles and previous meta-analyses. Treatment studies for depression with a subset of individuals with comorbid PD were included. Primary outcome was depression severity change during treatment. Effect sizes were estimated using random effect models, study-level variables were examined with meta-regression. Bias was assessed with the Risk of Bias tool.
Results: Six studies involving 942 individuals (447 with PD) were included. There was no significant difference in depression severity reduction between individuals with and without PD (g = 0.03, 95% CI -0.15-0.20, p = 0.27). Heterogeneity and risk of bias were low. The meta-regression did not yield significant results.
Conclusion: Findings don't indicate an impact of comorbid PD on the outcome of acute phase treatment for depression. Depressed patients with and without comorbid PD should receive the same evidence-based depression treatments.