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Pros and Cons of Continued Bisphosphonate Use


 

WASHINGTON – Physicians and patients need to work together to decide for or against long-term bisphosphonate treatment for osteoporosis. The body of evidence is still evolving, and there's no one-size-fits-all answer, said Dr. Sundeep Khosla, research chair of the division of endocrinology at the Mayo Clinic in Rochester, Minn.

“I think ultimately the patient has to decide with her physician. … Patient values factor into this,” said Dr. Khosla at an international symposium sponsored by the National Osteoporosis Foundation. A physician can inform a patient about the best information that is currently available in terms of fracture risk and the risk of complications. However, the patient has to decide what risk she is willing to take with regard to fracture.

Dr. Khosla discussed the pros and cons of long-term bisphosphonate use in the context of a hypothetical patient familiar to many physicians. A 60-year-old woman started on vitamin D/calcium supplements and 70 mg/week alendronate 5 years ago when her dual-energy x-ray absorptiometry (DXA) scan revealed a spine T score of −2.6 and a total hip T score of −2.0. She also has a family history of hip fracture. Her bone mineral density (BMD) has increased about 5% at the spine and 3% at the hip. She has not had any clinical fractures. She asks if she should continue with alendronate and if so, for how long.

So, should a patient who has been on alendronate for 5 years continue with therapy? In favor of continuing, it does appear that continuation will reduce the risk of clinical vertebral fractures.

Alendronate is the longest-available bisphosphonate, with 10 years of follow-up data. In one analysis of 10 years of data for postmenopausal women on varying regimens of alendronate, those on 10 mg daily of alendronate had increased BMD for the spine and hip (N. Engl. J. Med. 2004;350:1189-99). Spine BMD increased by 13.7% from baseline over that period, and total hip BMD increased by 6.7%. Smaller gains in BMD were noted for women on 5 mg daily of alendronate: 9.3% and 2.9% for the spine and total hip, respectively. For women in the discontinuation group, spinal BMD leveled off (an increase of 0.3% from years 6-10), and total hip BMD declined slightly (a decrease of 1% from years 6-10). There was an initial reduction in vertebral fractures for women on alendronate, but there was no difference in vertebral fractures during years 6-10. However, the study was not adequately powered to assess fractures.

This study “told us that alendronate did in fact have sustained effects over 10 years on bone density and bone turnover markers,” said Dr. Khosla. However, the fracture data were inconclusive: “At best, there was no clear evidence for an increase in vertebral or nonvertebral fractures following long-term alendronate therapy.”

Other data suggest that stopping treatment for 5 years will increase the risk of nonvertebral fractures and minor vertebral deformities.

In the FLEX (Fracture Intervention Trial [FIT] Long-Term Extension) study, published late last year, researchers assessed the effects of continuing or stopping alendronate after 5 years of treatment (JAMA 2006;296:2927-38). In this study, women who had received 5 years of alendronate therapy were randomized to continue on 5 mg/day or 10 mg/day alendronate, or to stop therapy.

For women on placebo for years 5-10, total hip BMD returned to baseline levels. Women on both doses of alendronate gained and maintained a 4% increase in hip BMD over baseline during the same period. In terms of spine BMD, women on placebo during years 5-10 had a slight increase, and women on alendronate had a steeper increase.

Women who continued on alendronate for 10 years had an almost 50% reduction in clinical vertebral fractures, compared with those who stopped treatment after 5 years. There was no difference between the groups in terms of nonvertebral or morphometric vertebral fractures.

“So if you look at clinical vertebral fractures, what you see is that if the BMD was greater than −2.0, there doesn't appear to be any real benefit [to continued alendronate]. But if you have a BMD less than −2.0 or less than −2.5 … it appears that both of these subgroups benefitted from continuing alendronate for 10 years as opposed to stopping it after 5 years.”

The study provides some useful clinical answers. “It says that continuation of alendronate for 10 years does maintain bone mass and reduces bone remodeling, compared with discontinuation after 5 years,” said Dr. Khosla. Discontinuation did not increase the risk of nonvertebral fractures or x-ray-detected vertebral fractures, but the risk of clinically detected vertebral fractures was significantly increased in those who discontinued therapy after 5 years.

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