The prevalence of forearm fractures increased with increasing degree of urbanization for both genders in the population-based study "Cohort Norway" with more than 180,000 participants. The differences were not explained by available risk factors. Prospective studies with information on bone mineral density and falls are warranted.
Introduction: The purpose was to investigate urban-rural gradients in self-reported forearm fractures and assess the contribution of possible explanatory factors.
Methods: "Cohort Norway" comprises ten population-based surveys inviting 309,742 individuals age 20 years and older. All 181,891 participants underwent a standardized examination and answered 50 common questions, including one concerning former forearm fractures. Based on the home-addresses, participants were divided into three population density groups: cities, densely populated areas and sparsely populated areas. Analyses were limited to 149,725 participants 30 years or over with valid information on exposure and outcome. Of these, 21,627 reported having suffered a forearm fracture.
Results: The prevalence of forearm fractures increased with increasing degree of urbanization for both genders. After adjustment for age and explanatory factors, the odds ratio of having sustained a forearm fracture in men living in densely populated areas and in cities were 1.12 (95% CI, 1.04-1.21) and 1.38 (95% CI, 1.30-1.46), respectively, compared to rural areas. Similar odds ratios were observed among women.
Conclusions: Prospective studies are needed to verify whether lower bone mineral density, different lifestyle and/or more falls may explain the higher proportion of self-reported forearm fractures found in urban compared to rural areas.