Risk of new vertebral fracture in the year following a fracture.

CONTEXT Vertebral fractures significantly increase lifetime risk of future fractures, but risk of further vertebral fractures in the period immediately following a vertebral fracture has not been evaluated. OBJECTIVE To determine the incidence of further vertebral fracture in the year following a vertebral fracture. DESIGN AND SETTING Analysis of data from 4 large 3-year osteoporosis treatment trials conducted at 373 study centers in North America, Europe, Australia, and New Zealand from November 1993 to April 1998. SUBJECTS Postmenopausal women who had been randomized to a placebo group and for whom vertebral fracture status was known at entry (n = 2725). MAIN OUTCOME MEASURE Occurrence of radiographically identified vertebral fracture during the year following an incident vertebral fracture. RESULTS Subjects were a mean age of 74 years and had a mean of 28 years since menopause. The cumulative incidence of new vertebral fractures in the first year was 6.6%. Presence of 1 or more vertebral fractures at baseline increased risk of sustaining a vertebral fracture by 5-fold during the initial year of the study compared with the incidence in subjects without prevalent vertebral fractures at baseline (relative risk [RR], 5.1; 95% confidence interval [CI], 3.1-8.4; P<.001). Among the 381 participants who developed an incident vertebral fracture, the incidence of a new vertebral fracture in the subsequent year was 19.2% (95% CI, 13.6%-24.8%). This risk was also increased in the presence of prevalent vertebral fractures (RR, 9.3; 95% CI, 1.2-71.6; P =.03). CONCLUSION Our data indicate that women who develop a vertebral fracture are at substantial risk for additional fracture within the next year.