The aetiology of posttraumatic stress disorder in four ethnic groups in outpatient psychiatry.

Background: PTSD is one of few diagnoses to be defined by its aetiology. At treatment centres specialising in a certain type of trauma, like war, torture or sexual abuse, the aetiology may be regarded as self-explanatory. Recent surveys of general populations reveal high rates of PTSD, often following exposure to multiple traumatic events. Traumas are frequently overlooked in general psychiatric settings and PTSD is underestimated. Such findings indicate the need to conceptualise trauma in terms of multiple events and to examine the aetiology of PTSD amongst patients in everyday psychiatric practice. The present study examines aetiological factors of PTSD in three minority groups at a general psychiatric outpatient clinic. Arabs, Iranians and Turks selected from an entire year's cohort of patients-and a sample of Swedish patients of similar age and gender distribution.

Methods: Histories were collected from 115 patients, both regarding their own traumas and traumas involving relatives and close friends, by means of a questionnaire. A self-rating instrument for PTSD, with no reference to a specific trauma, was used in order to study the relationship between trauma and PTSD outcome.

Results: Of the patients, 89% had experienced at least one trauma, and 77% multiple traumatic events. The prevalence of probable PTSD varied between ethnic groups: Iranians 69%, Arabs 59%, Turks 53% and Swedes 29%. In a logistic regression analysis, probable PTSD outcome was associated with multiplicity of relatives' traumas (OR = 3.14), multiplicity of own traumas (OR = 2.56) and belonging to an ethnic minority (OR = 2.44), but not with gender. No patient without a trauma history was positively assessed for probable PTSD.

Conclusion: The symptomatic syndrome of probable PTSD does not appear in the absence of extreme trauma, lending empirical support to the definition of PTSD. Prevalence increases with multiplicity of traumas, including those involving a relative or close friend. The high prevalence of probable PTSD found in this study warrants screening for trauma among patients, their relatives and close friends, in outpatient psychiatry.