Risk-factors and comorbidity of ICD-11 PTSD and Complex PTSD: Findings from a trauma-exposed population based sample of adults in the United Kingdom

Background: Following the recently published 11th version of the WHO International Classification of Diseases (ICD-11), we sought to examine the risk factors and comorbidities associated with posttraumatic stress disorder (PTSD) and Complex PTSD (CPTSD). Method: Cross-sectional and retrospective design. The sample consisted of 1051 trauma-exposed participants from a nationally representative panel of the UK adult population. Results: 5.3% (95% CI = 4.0%-6.7%) met the diagnostic criteria for PTSD and 12.9% (95% CI = 10.9%-15.0%) for CPTSD. Diagnosis of PTSD was independently associated with being female, being in a relationship, and the recency of traumatic exposure. CPTSD was independently associated with younger age, interpersonal trauma in childhood, and interpersonal trauma in adulthood. Growing up in an urban environment was associated with diagnosis of PTSD and CPTSD. High rates of physical and mental health comorbidity were observed for PTSD and CPTSD. Those with CPTSD were more likely to endorse symptoms reflecting Major Depressive Disorder (OR = 21.85, 95 CI = 12.51 – 38.04) and Generalized Anxiety Disorder (OR = 24.63, 95 CI = 14.77 – 41.07). Presence of PTSD (OR = 3.13, 95 CI = 1.81 – 5.41) and CPTSD (OR = 3.43, 95 CI = 2.37 – 4.70) increased the likelihood of suicidality by more than three times. Nearly half the participants with PTSD and CPTSD reported the presence of a chronic illness. Conclusions: CPTSD is a more common, co-morbid, debilitating condition compared PTSD. Further research is now required to identify effective interventions for its treatment.