Assessing the Prevalence of Trauma Exposure in Epidemiological Surveys

OBJECTIVE: Estimates of the prevalence of exposure to potentially traumatic events (PTEs) in population surveys have increased over time. There is limited empirical evidence on the impact of changes in measurement practices on these estimates. The present study examined the effect of increasing the number of events assessed on the prevalence of exposure longitudinally. METHODS: Data were ultilized from the 1997 and 2007 Australian National Surveys of Mental Health and Wellbeing. The 1997 survey assessed exposure using 11 items from the Composite International Diagnostic Interview (CIDI), version 2.1. The 2007 survey utilized 29 items from the World Mental Health CIDI. Prevalence rates of exposure to matched events among age-matched samples from both surveys were compared to determine whether differences in the estimates obtained were due to respondents having been asked about an increased number of event types in the latter survey. RESULTS: The effect of increasing the number of event types in the CIDI from 11 to 29 was to increase the overall population prevalence of exposure to PTEs by 18%. The difference between estimates was more pronounced in women than in men. The cross-cohort analyses revealed that these differences were not indicative of an increase in trauma exposure over time; but rather the endorsement of new events that were not listed in the earlier survey. CONCLUSIONS: The findings underscore the importance of using comprehensive assessments in the measurement of exposure to PTEs. Previous epidemiological surveys may have underestimated the prevalence of traumatic and other stressful life events, particularly among women.