Prevention of hip fractures: trade-off between minor benefits to individuals and large benefits to the community.

Goeffrey Rose postulated that a population-based measure bringing a small benefit to each individual can yield large benefits to the community. We aimed to test this axiom by quantifying the relationship between change in bone mineral density (BMD) and hip fracture incidence between two prospective cohorts separated by ~10 years. In this prospective population-based Dubbo Osteoporosis Epidemiology Study (DOES), the participants aged 60+ were recruited in two waves: the initial cohort (1311 women, 842 men) in 1989-1992, and the second cohort (974 women, 544 men) in 1999-2001. The incident hip fracture was radiologically ascertained. Femoral neck BMD was measured biannually. Multivariable-adjusted Cox's proportional hazards models were adjusted for the predefined covariates such as age, BMI, lifestyle factors, falls, and prior fracture. Compared with the initial cohort, the second cohort had a higher femoral neck BMD by ~ 0.04 g/cm 2 in women and 0.03 g/cm 2 in men. However, the prevalence of osteoporosis in the second cohort was halved (prevalence ratio 0.51, 95% CI 0.36-0.73 in women; 0.45, 0.24-0.84 in men), and its hip fracture incidence was significantly reduced (hazard ratio 0.54, 95% CI, 0.38-0.78 in women; 0.39, 0.19-0.80 in men). Sensitivity analyses indicated that the "effect" was unlikely due to unmeasured confounders. These findings suggest that a population-wide strategy aiming at enhancing BMD across the entire population could lead to a substantial decrease in the incidence of hip fractures. This article is protected by copyright. All rights reserved.