2. Substance use disorders in refugee and migrant groups in Sweden: A nationwide cohort study of 1.2 million people

Refugees are at higher risk of some psychiatric disorders, including post-traumatic stress disorder (PTSD) and psychosis, compared with other non-refugee migrants and the majority population. However, it is unclear whether this also applies to substance use disorders.

Using linked Swedish register data, we followed a cohort born between 1984-1997 from 14th birthday or arrival in Sweden, until a substance use diagnosis (F10.X–19.X), emigration, death, or end of follow-up (31.12.2016). We used Cox proportional hazards regression to estimate unadjusted and adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) in refugee and non-refugee migrants, compared with Swedish-born individuals, for all substance use disorders (F10.X–19.X), alcohol use disorders (F10.X), cannabis use disorders (F12.X), and polydrug use disorders (F19.X).

Our sample of 1,241,901 participants included 17,783 (1.4%) refugee and 104,250 (8.4%) nonrefugee migrants. Refugee groups were more economically disadvantaged at cohort entry (p < 0.001) than the Swedish-born population. Refugee (aHR: 0.52; 95% CI 0.46– 0.60) and non-refugee (aHR: 0.46; 95% CI 0.43–0.49) migrants had similarly lower rates of all substance use disorders compared with Swedish-born individuals (crude incidence: 290.2 cases per 100,000 person-years; 95% CI 287.3–293.1).

Rates of substance use disorders in migrants converged on the Swedish-born rate over time. We observed similar patterns for alcohol and polydrug use disorders. While a PTSD diagnosis was over 5 times more common in refugees than the Swedish-born population, it was more strongly associated with increased rates of substance use disorders in the Swedish born population than nonrefugee migrants.