Prevalence of exposure to potentially traumatic events and PTSD. The Zurich Cohort Study.

OBJECTIVE: The aim of this study was to estimate the prevalence rate of exposure to potentially traumatic events (PTE) and posttraumatic stress disorder (PTSD) in a representative sample of the general population.

METHOD: A representative community-based cohort from the canton of Zurich, Switzerland was interviewed in 1993 and 1999 at the age of 34/35 and 40/41 years, respectively, by means of a semi-structured diagnostic interview.

RESULTS: The weighted lifetime prevalence of PTE in 1999 was 28%. Of the persons who reported exposure to PTE (criterion A), none met all the remaining criteria for PTSD according to the DSM-IV. Eleven persons (2 males and 9 females) met the criteria for subthreshold PTSD. This corresponds to a weighted 12-month prevalence for subthreshold PTSD of 1.30% (0.26 % for males; 2.21 % for females). In 1993, no participant met all criteria for PTSD according to the DSMIII- R. The weighted 12-month prevalence for subthreshold PTSD was 1.90 % (2.9 % for males; 0.9 % for females).

CONCLUSION: The prevalence of exposure to PTE in Switzerland was relatively low. No single case of full PTSD was found in the sample, and even for subthreshold PTSD the prevalence was very low. The relatively stable socio-economic and political climate in Switzerland may contribute to a sense of safeness, which may protect Swiss citizens to some extent from developing PTSD in the aftermath of traumatic experiences.