Osteoporotic fractures in second-generation immigrants and Swedish natives

SUMMARY: In this national study of osteoporotic fractures in second-generation immigrants in Sweden, we found a similar risk of osteoporotic fractures in general compared to Swedish natives, which suggests that environmental factors are important for the high risk of osteoporotic fractures in Nordic countries. INTRODUCTION: Second generation immigrants may have a similar environment as individuals with two native-born parents. These individuals may be of interest to study concerning whether environmental or hereditary factors could be mostly associated to the risk of osteoporotic fractures. The aim of this study was to analyse the risk of osteoporotic fractures in second-generation immigrants compared to Swedish natives. METHODS: This was a nationwide study of individuals aged 50 years of age and older (N = 1,377,035; 691,750 men and 685,285 women). Osteoporotic fractures were defined as at least one registered diagnosis of fractures in the hip, humerus, forearm or vertebrae, in the National Patient Register between January 1, 1998, and December 31, 2012. Cox regression analysis was used to estimate the relative risk (hazard ratios (HR) with 95% confidence intervals (CI)) of incident osteoporotic fractures in second generation immigrants compared to Swedish natives. The Cox regression models were adjusted for age, comorbidities and for sociodemographic status. RESULTS: A total of 114,505 osteoporotic fractures were registered, 109,622 (8.4%) were among individuals with Swedish-born parents and 4883 (7.5%) among those with foreign-born parents, with distal forearm fractures dominating in general (44.9%). Fully adjusted HRs (95% CI) were for all immigrants 0.95 (95% CI, 0.91–0.99), for men 0.96 (95% CI, 0.89–1.04) and for women 0.95 (95% CI, 0.90–1.00). CONCLUSIONS: We observed a similar risk of osteoporotic fractures among second-generation immigrants as in Swedish natives, which suggests that environmental factors are important for osteoporotic fractures. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00198-020-05776-4.