High-trauma fractures and low bone mineral density in older women and men

Context It is widely believed that fractures resulting from high trauma are not osteoporotic; however, this assumption has not been studied prospectively. Objective To examine the association between bone mineral density (BMD) and high-trauma fracture and between high-trauma fracture and subsequent fracture in older women and men. Design, Setting, and Participants Two prospective US cohort studies in community-dwelling adults 65 years or older from geographically diverse sites. The Study of Osteoporotic Fractures followed up 8022 women for 9.1 years (1988-2006). The Osteoporotic Fractures in Men Study followed up 5995 men for 5.1 years (2000-2007). Main Outcome Measures Hip and spine BMD were assessed by dual-energy x-ray absorptiometry. Incident nonspine fractures were confirmed by radiographic report. Fractures were classified, without knowledge of BMD, as high trauma (due to motor vehicle crashes and falls from greater than standing height) or as low trauma (due to falls from standing height and less severe trauma). Results Overall, 264 women and 94 men sustained an initial high-trauma fracture and 3211 women and 346 men sustained an initial low-trauma fracture. For women, each 1-SD reduction in total hip BMD was similarly associated with an increased risk of high-trauma fracture (multivariate relative hazard [RH], 1.45; 95% confidence interval [CI], 1.23-1.72) and low-trauma fracture (RH, 1.49; 95% CI, 1.42-1.57). Results were consistent in men ( high-trauma fracture RH, 1.54; 95% CI, 1.20-1.96; low-trauma fracture RH, 1.69; 95% CI, 1.49-1.91). Risk of subsequent fracture was 34%( 95% Cl, 7%-67%) greater among women with an initial high-trauma fracture and 31%( 95% Cl, 20%-43%) greater among women with an initial low-trauma fracture, compared with women having no high- or low trauma fracture, respectively. Risk of subsequent fracture was not modeled for men. Conclusions Similar to low-trauma nonspine fractures, high- trauma nonspine fractures are associated with low BMD and increased risk of subsequent fracture in older adults. High-trauma nonspine fractures should be included as outcomes in osteoporosis trials and observational studies.