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.