Using Latent Class Analysis to Support the ICD-11 Complex Posttraumatic Stress Disorder Diagnosis in a Sample of Homeless Adults

The 11th revision of the International Classification of Diseases (ICD-11), ratified at the World Health Assembly in May 2019, introduced revised diagnostic guidelines for posttraumatic stress disorder (PTSD) as well as a separate diagnosis of complex PTSD (CPTSD). We aimed to test the new ICD-11 symptom structure for PTSD and CPTSD in a sample of individuals who have experienced homelessness. Experiences of trauma exposure and the associated mental health outcomes have been underresearched in this population. A sample of adults experiencing homelessness (N = 206) completed structured and semi-structured interviews that collected information about trauma exposure and symptoms of PTSD and CPTSD. We conducted a latent class analysis (LCA) using six symptom clusters (three PTSD symptom clusters that are components of CPTSD and three CPTSD symptom clusters). All participants reported trauma exposure, with 88.6% having experienced at least one event before 16 years of age. Four distinct classes of participants emerged in relation to the potential to meet the diagnosis: LCA CPTSD (n = 122, 59.8%), LCA no diagnosis (n = 27: 13.2%), LCA PTSD (n = 33; 16.2%), and LCA disturbance in self-organization (DSO; n = 22; 10.8%). Of note, participants with an ICD-11 CPTSD as well as those with an ICD-11 PTSD diagnosis fell into the LCA CPTSD class. Our findings provide some support for the distinction between CPTSD and PTSD within this population specifically but potentially have broader implications. Clear diagnoses will allow targeted PTSD and CPTSD treatment development.