Ethnic differences in risk of hip fracture in Norway: a NOREPOS study

Hip fracture is a major public health problem, and the incidence rates vary considerably between countries. Ethnic differences in bone mineral density have been identified as a factor to explain some of the geographical differences in rates of hip fracture. In this Norwegian register-based study, we found that all immigrant groups experienced lower risk of hip fracture than individuals born in Norway. Introduction Norway is among the countries with the highest incidence rates. The aim of this study was to investigate differences in risk of hip fracture between ethnic groups living in Norway. Methods We linked individuals in the Norwegian Population and Housing Census conducted in 2001 and a database consisting of all hip fractures in Norway in the period 2001-2013. Residents (n = 1,392,949) between 50 and 89 years and born in nine different geographical regions of the world were examined, and we computed age-standardized incidence rates for the different geographic regions-denoted ethnic groups in the paper. Gender-stratified Cox regression analysis, adjusted for age, was used to model risk of hip fracture as a function of region of birth. Results Age-standardized incidence rates of hip fracture varied considerably between regions of birth living in Norway, in both genders. All immigrant groups had lower risk of hip fracture compared to the Norwegian-born population. Immigrants from Central and Southeast Asia had the lowest risk of hip fracture when compared to individuals born in Norway (HR = 0.2, 95% CI 0.1-0.3 and HR =0.2, 95% CI 0.2-0.4 in men and women, respectively). Conclusion Lower risk of hip fracture was found in all immigrant groups compared to the Norwegian-born majority population.