Zoledronate infusions every 5 years may lower fracture risk for early postmenopausal women
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Key takeaways:
- Women who went 5 years between zoledronate infusions had a 44% lower risk for morphometric vertebral fractures than women receiving placebo.
- More research is needed to assess the optimal dosing regimen.
Early postmenopausal women who receive zoledronate every 5 years have a lower risk for morphometric vertebral fractures than those receiving placebo, according to trial findings published in The New England Journal of Medicine.
“The results show that prevention of vertebral fractures in early postmenopausal women is possible with very infrequent infusions of zoledronate,” Mark J. Bolland, MB, ChB, PhD, associate professor in the faculty of medicine and health sciences at the University of Auckland in New Zealand, and colleagues wrote. “The relative risks for any fracture observed in the current trial are similar to those observed in trials of zoledronate in older women and in persons at higher risk of fracture. Early postmenopausal women who wish to reduce their risk of fracture could consider a strategy involving the administration of zoledronate either every 5 years or every 10 years.”
Researchers conducted a randomized, double-blind, placebo-controlled trial enrolling 1,054 postmenopausal women aged 50 to 60 years with a bone mineral density T-score of less than 0 at the lumbar spine, femoral neck or total hip (mean age at baseline, 56 years). Participants were randomly assigned, 1:1:1, to a 5 mg infusion of zoledronate at baseline and at 5 years; a 5 mg infusion of zoledronate at baseline followed by a saline placebo infusion at 5 years; or an infusion of saline placebo at baseline and 5 years. Women were followed for up to 10 years. Incident morphometric vertebral fractures were confirmed through spinal radiographs.
At 10 years, morphometric vertebral fractures were confirmed in 6.3% of women receiving zoledronate at baseline and 5 years, 6.6% of those receiving zoledronate at baseline and placebo at 5 years, and 11.1% of women receiving placebo at baseline and 5 years. Women receiving zoledronate at baseline and 5 years (RR = 0.56; 95% CI, 0.34-0.92; P = .04) and those receiving zoledronate at baseline and placebo at 5 years (RR = 0.59; 95% CI, 0.36-0.97; P = .08) had a lower risk for morphometric vertebral fractures than women receiving placebo at baseline and 5 years. When both zoledronate groups were combined, the therapy conferred a 42% lower risk for morphometric vertebral fracture vs. placebo (RR = 0.58; 95% CI, 0.38-0.87). There was no significant difference in morphometric vertebral fracture risk between the two zoledronate groups.
Women receiving zoledronate at both baseline and 5 years (RR = 0.7; 95% CI, 0.56-0.88) and those receiving zoledronate at baseline and placebo at 5 years (RR = 0.77; 95% CI, 0.62-0.97) had a lower risk for any fracture than women receiving placebo at baseline and 5 years. Findings were similar when researchers examined risk for fragility fractures and major osteoporotic fractures.
Women in both zoledronate groups had higher BMD at the total hip and spine at 5 and 10 years than women receiving placebo only. Zoledronate therapy was tied to a 30% to 40% reduction in bone turnover markers at 5 years. Bone turnover markers remained below baseline levels at 10 years.
Few adverse events were reported during the trial. Of women receiving zoledronate, 1.1% had uveitis and 0.1% had episcleritis at baseline. There were no reports of either condition at 5 years.
The researchers cautioned the trial findings may differ for older women, men or those with osteoporosis. Additionally, they wrote that more research is needed to examine what the optimal dosing strategy may be for zoledronate.
“It is possible that more frequent dosing intervals for zoledronate as used in previous studies, such as annual or every 18 months, might be more effective than the intervals used in our trial, particularly in persons with a higher risk of fracture,” the researchers wrote.
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