Risk of psychopathology following traumatic events among immigrants and native-born persons in Denmark

Purpose: Immigrants may have increased risk of mental disorders compared with native-born persons. We aimed to expand the limited research on immigrants' posttraumatic psychopathology related to traumatic experiences in their country of resettlement.

Methods: We obtained data from a cohort of Danish residents with ≥ 1 traumatic event recorded in health and administrative national registries during 1994-2016. We calculated risks of posttraumatic stress disorder (PTSD), depression, and substance use disorders (SUD) within 5 years post-trauma among native-born Danes and immigrants who had been in Denmark for ≥ 10 years at the time of their index trauma (including immigrants overall and immigrants from specific regions). Risks were compared via age- and sex-standardized risk ratios (SRR) with 95% confidence intervals (CI). We restricted to persons with no record of the disorder under investigation in the 10 years pre-trauma, and stratified by non-interpersonal (e.g., transport accidents) versus interpersonal trauma (e.g., assaults).

Results: Following non-interpersonal trauma, immigrants were more likely than native-born Danes to be diagnosed with PTSD (SRR = 5.2, 95% CI 4.6, 5.9), about as likely to be diagnosed with depression (SRR = 0.98, 95% CI 0.92, 1.1), and less likely to be diagnosed with SUD (SRR = 0.89, 95% CI 0.82, 0.95). Results were similar following interpersonal trauma, except the SRR for PTSD was reduced in magnitude (SRR = 3.0, 95% CI 1.7, 5.4). There were differences by region of birth.

Conclusion: Immigrants to Denmark have higher risk of PTSD following traumatic experiences than do native-born Danes, possibly due to the combined influence of adverse pre-, peri-, and/or post-migration experiences.