Vertebral fractures and mortality in older women: a prospective study. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Osteoporotic fractures, including clinically detected vertebral fractures, are associated with increased mortality. However, only one third of vertebral fractures are diagnosed. It is unknown whether vertebral fractures, whether clinically apparent or not, are associated with greater mortality. OBJECTIVES: To test the hypothesis that women with prevalent vertebral fractures have greater mortality than those without fractures and to describe causes of death associated with vertebral fractures. DESIGN: Prospective cohort study with mean follow-up of 8.3 years. SETTING: Four clinical centers in the United States. PARTICIPANTS: A total of 9575 women aged 65 years or older and enrolled in the Study of Osteoporotic Fractures. MEASUREMENTS: Vertebral fractures by radiographic morphometry; calcaneal bone mineral density; demographic, medical history, and lifestyle variables; blood pressure; and anthropometric measures. In a subset of 606 participants, thoracic curvature was measured during a second clinic visit. MAIN OUTCOME MEASURES: Hazard ratios for mortality and cause-specific mortality. RESULTS: At baseline, 1915 women (20.0%) were diagnosed as having vertebral fractures. Compared with women who did not have a vertebral fracture, women with 1 or more fractures had a 1.23-fold greater age-adjusted mortality rate (95% confidence interval, 1.10-1.37). Mortality rose with greater numbers of vertebral fractures, from 19 per 1000 woman-years in women with no fractures to 44 per 1000 woman-years in those with 5 or more fractures (P for trend, <.001). In particular, vertebral fractures were related to the risk of subsequent cancer (hazard ratio, 1.4;95% confidence interval, 1.1-1.7) and pulmonary death (hazard ratio, 2.1;95% confidence interval, 1.4-3.0). In the subset of women who underwent thoracic curvature measurements, severe kyphosis was also related to pulmonary deaths (hazard ratio, 2.6;95% confidence interval, 1.3-5.1). CONCLUSION: Women with radiographic evidence of vertebral fractures have an increased mortality rate, particularly from pulmonary disease and cancer.