Depression, falls, and risk of fracture in older women

Background: Previous studies have suggested that depression is associated w ith falls and with low bone density, but it is not known whether depression leads to an increased risk of fracture. Subjects and Methods: We conducted a prospective cohort study in elderly wh ite women who were recruited from population-based listings in the United S tates. At a second visit (1988-1990), 7414 participants completed the 15-it em Geriatric Depression Scale and were considered depressed if they reporte d 6 or more symptoms of depression. We measured bone mineral density (BMD) in the spine and hip using dual energy x-ray absorptiometry at the second v isit, and asked participants about incident falls (yes/no) at 4 follow-up v isits. Nonvertebral fractures were ascertained for an average of 6 years fo llowing the depression measure, and verified radiologically. We determined incident vertebral fractures by comparing lateral spine films obtained at t he first visit (1986-1988) with repeat films obtained an average of 3.7 yea rs later (1991-1992). Results: The prevalence of depression (Geriatric Depression Scale score gre ater than or equal to 6) was 6.3% (467/7414). We found no difference in mea n BMD of the hip and lumbar spine in women with depression compared with th ose without depression. Women with depression were more likely to experienc e subsequent falls than women without depression (70% vs 59%; age-adjusted odds ratio [OR], 1.6; 95% confidence interval [CI], 1.3-1.9; P < .001), an association that persisted after adjusting for potential confounding variab les (OR, 1.4; 95% CI, 1.1-1.8; P = .004). Women with depression had a 40% ( age-adjusted hazard ratio [HR], 1.4; 95% CI, 1.2-1.7; P < .001) increased r ate of nonvertebral fracture (124 fractures in 3805 woman-years of follow-u p) compared with women without depression (1367 fractures in 59 503 woman-y ears of followup). This association remained strong after adjusting for pot ential confounding variables, including medication use and neuromuscular fu nction (HR, 1.3; 95% CI, 1.1-1.6; P = .008). Further adjustment for subsequ ent falls appeared to explain part of this association (HR, 1.2; 95% CI, 1. 0-1.5; P = .06). Women with depression were also more likely to suffer vert ebral fractures than women without depression, adjusting for history of ver tebral fracture, history of falling, arthritis, diabetes, steroid use, estr ogen use, supplemental calcium use, cognitive function, and hip BMD (OR, 2. 1; 95% CI, 1.4-3.2; P < .001). Conclusions: Depression is a significant risk factor for fracture in older women. The greater frequency of falls among individuals with depression par tially explains this finding. Other mechanisms responsible for the associat ion between depression and fracture remain to be determined.