Self-rated personality disorder symptoms do not predict treatment outcome for posttraumatic stress disorder in routine clinical care

Objective: To test the hypothesis that self-rated personality disorder (PD) symptoms are a significant and clinically relevant predictor of treatment outcomes in a naturalistic treatment setting specialized in trauma-focused treatment using a single-group pretest–posttest design. Method: Treatment-seeking patients reporting clinical levels of posttraumatic stress disorder (PTSD) symptoms filled out questionnaires at intake and after treatment. The primary outcome was change in PTSD severity after treatment, measured by the PTSD Checklist for DSM-5 (PCL-5). PD symptoms were measured with the Structured Clinical Interview for DSM-5 Screening Personality Questionnaire (SCID-5-SPQ). Secondary outcomes were general mental health problems, treatment response, number of sessions and dropout. Results: N = 1174 patients (59% female, baseline PCL-5 score M [SD] = 53.0 [10.8]) were included for the primary analysis. Regression analysis revealed that PD symptoms explained 0.4% of variance in PTSD symptom change (p =.066). After controlling for baseline PTSD symptoms, PD symptoms explained 0.0% of variance (p =.311). The fully adjusted model including baseline PTSD symptom severity, age, gender, cumulative exposure to potentially traumatic experiences, PD symptoms, and number of sessions together explained 5% of the observed variance in PTSD symptom change. Baseline PTSD severity was the only significant predictor and negatively predicted outcome. Sensitivity analyses with imputed data from N = 2694 cases yielded comparable results. Finally, secondary analyses showed that PD symptoms did not predict significant or clinically relevant changes in treatment response status, general mental health problems, dropout rates or number of sessions. Conclusion: The findings provide no evidence that self-rated PD symptoms predict treatment outcomes for patients suffering from clinical levels of PTSD symptoms in a naturalistic treatment setting specializing in trauma-focused treatment. Self-report screening for these symptoms to inform clinicians about expected effects of PTSD treatment is not supported by the evidence.