Incidence and risk factors for osteoporotic non-vertebral fracture in low-income community-dwelling elderly: a population-based prospective cohort study in Brazil. The São Paulo Ageing and Health (SPAH) study

Abstract

We ascertained the incidence of non-vertebral fracture in a low-income Brazilian elderly cohort. To the best of our knowledge, this is the first population-based study to demonstrate the frequency of non-vertebral fracture in elderly Latin Americans. Age, prior fracture, and bone mineral density (BMD) at hip were predictors of fracture.

Introduction: No data on incidence of osteoporotic non-vertebral fracture have been reported in low-income countries where the population's aging has been faster. Even in developed countries, currently available prospective data on major fracture rates beyond hip are scarce. The aim of this study is to describe the incidence and risk factors for non-vertebral fracture in a longitudinal prospective Brazilian population-based elderly cohort.

Methods: Seven hundred seven older adults (449 women, 258 men) were evaluated at baseline and after a mean follow-up of 4.3 ± 0.8 years. Clinical questionnaire, bone mineral density (BMD), and laboratory tests were performed at baseline. New non-vertebral fracture (hip, proximal humerus, rib, forearm) was determined during the follow-up. Multivariate Poisson regression models were used to identify independent predictors of fracture.

Results: The age-standardized incidence of non-vertebral fracture was 1562.3/100,000 (1085.7-2248.1/100,000) person-years (pyr) in women and 632.8/100,000 (301.7-1327.3/100,000) in men. Concerning to hip fractures, the incidence was 421.2/100,000 (210.7-842.3/100,000) pyr in women and 89.9/100,000 (12.7-638.5/100,000) in men. In a multivariate analysis, age (RR 2.07, 95% CI 1.13-3.82, p = 0.019, each 10-year increase), prior non-vertebral fracture (RR 3.08, 95% CI 1.36-6.95, p = 0.007), and total hip BMD (RR 1.68, 95% CI 1.11-2.56, p = 0.015, each 1 SD decrease) were predictors of new non-vertebral fracture. In men, fitting a model of risk factors for fracture was prevented by the limited number of events in male sample.

Conclusion: This is the first population-based study to ascertain the incidence of major non-vertebral fractures in elderly Latin Americans, confirming the high frequency of the disorder. Age, prior fracture, and hip BMD were predictors of the short-term incidence of fracture.

Keywords: Age-standardized incidence; Aging; Hip fracture; Non-vertebral fracture; Osteoporosis; Risk factors.