Objective: To establish factors associated with ICD-11 post-traumatic stress disorder (PTSD) and complex PTSD (CPTSD) in a large sample of adults with lived experience of psychiatric disorder and examine the psychiatric burden associated with the two disorders.Methods: One thousand three hundred and five adults were recruited from the National Centre for Mental Health (NCMH) cohort. ICD-11 PTSD/CPTSD were assessed with the International Trauma Questionnaire (ITQ).