Rates and characteristics of suicide by immigration background in Norway

Suicide mortality among immigrant groups is an important health issue, particularly in countries with growing segments of immigrant populations such as Norway. Through linkage of Norwegian national registers we wanted to estimate suicide rates (per 100,000 population) in immigrant groups and to profile characteristics of suicide by immigration background with respect to sex, age, method and seasonality of suicide as well as time since immigrating to Norway. Among all 11,409 suicides during 1992-2012, 1,139 (10%) were individuals with an immigration background. Suicide rate was lower in first-generation immigrants (foreign-born persons to two foreign-born parents) than native Norwegians (9.53 vs 12.22, P < 0.01), with a significant difference confined to male rates only. Foreign-born persons with at least one Norwegian-born parent had significantly higher suicide rates than natives in both sexes (22.42 vs 18.03 in males, 11.67 vs 6.54 in females, P < 0.01). The most frequently used suicide method in all the population groups was hanging; this method accounted for 44.0% of all suicides of first-generation immigrants, 45.2% of all suicides of foreign-born persons with at least one Norwegian-born parent, and 35.4% of all suicides of natives. Suicide by firearms accounted for a much smaller proportion of cases of first-generation immigrants (6.7%) and foreign-born persons with at least one Norwegian-born parent (6.8%) than cases of native Norwegians (20.7%). In terms of monthly distribution, suicides of first-generation immigrants displayed two peaks, in May and in November (P = 0.01). More than 25% of all first-generation immigrant suicides occurred in the first five years after immigration; but differences in time since immigration were observed by sex and country group of origin, in particular among those aged 35 years or less when moving to Norway. In conclusion, there are notable differences in characteristics of suicides by immigration background. Knowledge of immigrant mortality according to suicide method, seasonality of suicide, and time since immigration may be useful when planning suicide preventive measures.