The frequency and correlates of complex post-traumatic stress disorder among patients being treated for borderline personality disorder: cross-sectional study

Background Despite overlapping diagnostic criteria and aetiology, the frequency of complex post-traumatic stress disorder (C-PTSD) in people being treated for borderline personality disorder (BPD) is unknown. Aims To establish the frequency and correlates of probable C-PTSD in people meeting the diagnostic criteria and being treated for BPD. Method C-PTSD was assessed in 87 patients meeting the diagnostic criteria for BPD and initiating treatment in out-patient personality disorder services in the UK, using the Structured Clinical Interview for DSM-IV Axis II Personality Disorders diagnostic interview, items from the Structured Interview for Disorders of Extreme Stress – Self Report and other measures. The cross-sectional association between C-PTSD and demographics, trauma and clinical variables was evaluated with logistic, ordinal and linear regression. Results A total of 93% of participants reported a trauma history (95% CI 88–98%), and 57% met the criteria for probable C-PTSD (95% CI 47–67%). Previous sexual trauma increased the odds of probable C-PTSD (odds ratio 6.22, 95% CI 2.21–17.54, P < 0.001). Probable C-PTSD was associated with an increased odds of self-harm in the past 12 months (odds ratio 9.41, 95% CI 1.87–47.27, P = 0.01) and higher levels of abandonment fears (odds ratio 2.78, 95% CI 1.17–6.55, P = 0.02), abandonment–avoidant behaviour (odds ratio 4.25, 95% CI 1.30–13.91, P = 0.02) and identity instability (odds ratio 4.39, 95% CI 1.79–10.78, P < 0.01). Conclusions C-PTSD symptoms are likely to be common in people diagnosed with BPD, and are associated with higher overall psychiatric severity, with potential implications for formulation and treatment.