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.
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.
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.
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).
Our data indicate that women who develop a vertebral fracture are at
substantial risk for additional fracture within the next year.