Low bone mineral density and risk of fracture in white female nursing home residents

Context Low bone mineral density (BMD) is a strong risk factor for fracture in community-dwelling white women, but the relationship in white female nursing home residents, for whom fracture rates are highest, is less clear, Objective To assess the relative contribution of low BMD to fracture risk in nursing home residents. Design Prospective cohort study with baseline data collected April 1995 to June 1997, with 18 months of follow-up. Setting Forty-seven randomly selected nursing homes in Maryland. Patients A total of 1427 white female nursing home residents aged 65 years or older. Main Outcome Measure Documented osteoporotic fracture occurring during follow-up as a function of baseline BMD measurements higher vs lower than the median, and after controlling for demographic, functional, cognitive, psychosocial, and medical factors. Results A total of 223 osteoporotic fractures occurred among 180 women. Low BMD and transfer independence were significant independent risk factors for fracture in this nursing home sample (P<.001) and the 2 factors acted synergistically (P=.06) to further increase fracture risk. Compared with women whose BMD was higher than the median (0.296 g/cm(2)), those whose BMD was lower than the median had an unadjusted hazard ratio for risk of fracture of 2.1 (95% confidence interval [CI], 1.5-2.8); women who were independent in transfer had a hazard ratio of 1.6 (95% CI, 1.2-2.2) compared with women dependent in transfer. Among residents independent in transfer, those with BMD below the median had a more than 3-fold increase in fracture risk compared with those with higher BMD (unadjusted hazard ratio, 3.1; 95% CI, 2.2-4.4). Among residents dependent in transfer, those with BMD below the median had a 60% increase in fracture risk (unadjusted hazard ratio, 1.6; 95% CI, 1.1-2.3). Adjustment for covariates did not alter the BMD-fracture relationship, Conclusions Our data indicate that low BMD and independence in transfer are significant predictors of osteoporotic fracture in white female nursing home residents.