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. JAMA. 2000;284:972-977