Suicidal Behaviour Has Decreased in International Adoptees: A Swedish National Cohort Study

Abstract

Background: A previous Lancet article about international adoptees in Sweden showed a three-to fourfold higher risk of suicidal behaviour in youth during 1986-1995. The aim of this study was to investigate whether this high risk persists during later years, beyond youth and in later cohorts. Methods: Register study in Swedish national cohorts born 1972-86 including 20,625 non-European international adoptees, and comparison populations of 10 915 non-European immigrants and 1 435 167 Swedish born. The study population was followed from age 18 to the year 2016 with suicide death and hospital admissions due to suicide attempt as outcomes. Poisson regression models of person time in the study, adjusted for gender and household income at age 17, were fitted to calculate relative risks (RR). Outcomes: Adjusted RR for suicide death in international adoptees was high at age 18-22, 2·74 (95% C.I. 1·95-3·86), but decreased gradually to age 33-43 when the risk was similar to Swedish-born. Adjusted RR for suicide attempts in international adoptees was 2·33 (2·15-2·52) at age 18-22, decreased slightly with older age, but remained higher than Swedish born in all age-classes. Risks for both outcomes were greatest, around three times higher compared with the majority population, in the oldest birth cohorts of international adoptees, born 1972-76. Risks for both suicide outcomes increased with higher age at adoption. Interpretation: The risk of suicidal behaviour in international adoptees in Sweden decreases in middle age and is lower in later birth cohorts and in infant adoptions. Funding Statement: None to declare. Declaration of Interests: Dr. Lindblad reports that he is an adoptive father, all other authors have nothing to declare. Ethics Approval Statement: Our study has been approved by the Regional ethics committee in Stockholm region (No. 2014/415-31/5).