Risk of subsequent fractures and mortality in elderly women and men with fragility fractures with and without osteoporotic bone density: the Dubbo Osteoporosis Epidemiology Study

Abstract

Half of fragility fractures occur in individuals with nonosteoporotic BMD (BMD T-score > -2.5); however, there is no information on postfracture adverse events of subsequent fracture and mortality for different BMD levels. The objective of this work was to determine the risk and predictors of subsequent fracture and excess mortality following initial fracture according to BMD. The subjects were community-dwelling participants aged 60+ years from the Dubbo Osteoporosis Epidemiology Study with incident fractures followed from 1989 to 2011. The outcome measurements were as follows: risk of subsequent fracture and mortality according to BMD categorized as normal (T-score < -1), osteopenia (T-score ≤ -1 and > -2.5), and osteoporosis (T-score ≤ -2.5). There were 528 low-trauma fractures in women and 187 in men. Of these, 12% occurred in individuals with normal BMD (38 women, 50 men) and 42% in individuals with osteopenia (221 women, 76 men). The relative risk (RR) of subsequent fracture was >2.0-fold for all levels of BMD (normal BMD: 2.0 [1.2 to 3.3] for women and 2.1 [1.2 to 3.8] for men; osteopenia: 2.1 [1.7 to 2.6] for women and 2.5 [1.6 to 4.1] for men; and osteoporosis 3.2 [2.7 to 3.9] for women and 2.1 [1.4 to 3.1] for men. The likelihood of falling and reduced quadriceps strength contributed to subsequent fracture risk in women with normal BMD. By contrast with subsequent fracture risk, postfracture mortality was increased particularly in individuals with low BMD (age-adjusted standardized mortality ratio [SMR] for osteopenia 1.3 [1.1 to 1.7] and 2.2 [1.7 to 2.9] for women and men, respectively, and osteoporosis 1.7 [1.5 to 2.0] and 2.7 [2.0 to 3.6] for women and men, respectively). This study demonstrates the high burden of subsequent fracture in individuals with normal BMD and osteopenia, and excess mortality particularly for those with osteopenia (and osteoporosis). These findings highlight the importance of these fractures and underscore the gap in evidence for benefit of antiosteoporotic treatment for fragility fracture, in those with only mildly low BMD.

Keywords: BONE MINERAL DENSITY; EPIDEMIOLOGY; FRACTURE PREVENTION; FRACTURE RISK; MORTALITY RISK; OSTEOPOROSIS; PRACTICE/POLICY-RELATED ISSUES.