Trauma history and relapse probability among patients seeking substance abuse treatment.

We estimated the prevalence of trauma history and relapse in a sample of 959 patients at two outpatient chemical dependence clinics of a managed healthcare organization. A large majority (89%) reported a history of at least one traumatic event. The most common traumatic events were serious accidents, being robbed, seeing someone killed or seriously injured, and partner violence. One third of the patients had a history of substance abuse disorder relapse. There were gender and ethnic differences in the types of traumatic events reported. There were ethnic differences in relapse rates, which were highest among African American and multicultural patients. The types of traumatic events reported differed in patients of various sexual orientations. Bisexual patients had the highest rates of relapse, even when trauma exposure was controlled. Clinical implications of the findings are discussed.