Osteoporotic fractures among foreign-born individuals registered in Sweden before and after the age of 30 years

Purpose

To analyse risk of osteoporotic fractures in foreign-born individuals migrating to Sweden at different ages, compared to Swedish-born individuals.

Methods

This was a nationwide open cohort study including individuals ≥30 years of age at baseline (N = 4,715,081). Foreign-born individuals were divided as having arrived to and being registered in Sweden from the ages 0–30 years of age or >30 years of age. Osteoporotic fractures were defined as at least one registered diagnosis of fractures in the hip, humerus, forearm, vertebrae, or pelvis, in the National Patient Register between January 1, 1998, and December 31, 2018. Cox regression analysis was used to estimate relative risk (hazard ratios (HR) with 99 % confidence intervals (CI)) of incident osteoporotic fractures in foreign-born compared to Swedish-born individuals. Cox regression models were stratified by sex and adjusted for age, co-morbidities, and sociodemographic status.

Results

Totally 304,462 fractures (men n = 82,992, and women n = 221,470) were registered, with hip fractures dominating (54.0 % among men, 42.6 % among women). Fully adjusted HRs (99 % CI) were for foreign-born men registered at the age 0–30 years 0.81 (0.78–0.85) and 0.73 (0.69–0.78) for foreign-born men above 30 years, respectively. The corresponding risk for foreign-born women registered at the age 0–30 years was 0.92 (0.90–0.95) and 0.84 (0.80–0.88) for foreign-born women registered above 30 years.

Conclusions

We found slightly different risks of osteoporotic fractures among immigrants, but with no statistically significant interaction between risks for those being registered in Sweden at the age above 30 years vs those registered until this age.

Summary

In this national study of osteoporotic fractures in foreign-born individuals, the fracture risk did not differ by age at immigration.