Karatzias T, et al. - Researchers ought to study the risk factors and comorbidities correlated with posttraumatic stress disorder (PTSD) and complex PTSD (CPTSD) following the recently published 11th version of the WHO International Classification of Diseases (ICD-11). Of 1,051 trauma-exposed participants from a nationally representative panel of the UK adult population, 5.3% fulfilled the diagnostic criteria for PTSD and 12.9% for CPTSD. Being female, being in a relationship and the recency of traumatic exposure were noted to be independently associated with the diagnosis of PTSD. Younger age, interpersonal trauma in childhood and interpersonal trauma in adulthood were independently associated with CPTSD. The diagnosis of PTSD and CPTSD were also noted in correlation with growing up in an urban environment. Physical and mental health comorbidities were observed in high rates for PTSD and CPTSD. Symptoms reflecting major depressive disorder and generalized anxiety disorder were more frequent among those with CPTSD. Increase in the likelihood of suicidality by more than three times was noted in the presence of PTSD and CPTSD. Chronic illness was evident in nearly half the participants with PTSD and CPTSD. These findings suggest that compared to PTSD, CPTSD is a more common, comorbid, debilitating condition.