Fall Severity and Bone Mineral Density as Risk Factors for Hip Fracture in Ambulatory Elderly

Abstract

OBJECTIVE: To determine the relative importance of fall characteristics, body habitus, and femoral bone mineral density (BMD) in predicting hip fracture in community-dwelling elderly. DESIGN: Prospective case-control study. SETTING: Community-based academic hospital. PARTICIPANTS: A total of 149 ambulatory, community-dwelling fallers (126 women, 23 men) aged 65 years and older, including 72 case patients (fallers with hip fracture) and 77 control fallers (fallers with no hip fracture). MAIN OUTCOME MEASURES: Fall characteristics, body habitus, femoral BMD. RESULTS: Significant and independent risk factors for hip fracture in both sexes were direction of the fall (adjusted odds ratio [OR], 5.7; 95% confidence interval [CI], 2.3 to 14.0; P < .001); femoral neck BMD (a decrease of 1 SD; adjusted OR, 2.7; 95% CI, 1.6 to 4.6; P < .001); potential energy of the fall (an increase of 1 SD; adjusted OR, 2.8; 95% CI, 1.5 to 5.2; P < .001); and body mass index (a decrease of 1 SD; adjusted OR, 2.2; 95% CI, 1.2 to 3.8; P < .01). Importantly, the OR for the fall direction was unaffected by the addition or removal of BMD from the model. CONCLUSIONS: We conclude that among elderly fallers--in most of whom hip BMD is already less than the fracture threshold--fall characteristics and body habitus are important risk factors for hip fracture and touch on a domain entirely missed by knowledge of BMD. These data suggest new targets for preventive therapy. In addition to the maintenance of bone density, reductions in fall severity (eg, by use of trochanteric padding or enhancement of muscle strength) may provide additional strategies for prevention of hip fracture in this age group.