Common bone drugs increase risk of rare fractures: Study

Canadian researchers find that bisphosponates like Fosamax may cause users to be 2.7 times more likely to suffer an injury such as Fosamax Femur Fracture.

- CalgaryHerald.com

03/02/2011 - Drugs widely prescribed to keep bones from breaking down increase the risk of rare and unusual fractures of the thigh bone, a large new Canadian study suggests.

Toronto researchers found that women who take bisphosphonates for five years or more were 2.7 times more likely to be hospitalized for fractures in the femur — the long bone that extends from the hip to the knee — compared with women who took the drugs for less than 100 days in total.

The absolute risk was low: for women who had taken the drugs for five years or more, the risk of a thigh bone fracture was about one in 1,000. And the Toronto team confirmed that the drugs lower the risk of more common hip fractures.

But experts say the study underscores that the pills should be prescribed only for women at high risk of osteoporosis-related fractures, including women who have suffered a previous fracture. The drugs have also been linked with increased risks of atrial fibrillation, the most common heart rhythm disturbance that increases the risk of stroke, as well as an increased risk of necrosis of the jaw.

"Unfortunately a considerable number of women who are receiving these medications may not really need them," said Mahyar Etminan, of the Center for Clinical Epidemiology and Evaluation and the department of medicine at the University of British Columbia. Just over 7.5 million prescriptions for bisphosphonates worth $356 million were sold in Canadian pharmacies last year, according to prescription drug-tracking firm IMS Brogan.

"A lot of the women prescribed these drugs only have osteopenia (low bone mineral density) or thinning of the bone. In these women the benefit of the drugs is minimal," Etminan said. Some studies suggest that, for lower-risk women, "calcium and vitamin D would probably give them equal benefit."

The new study isn't the first to link long-term use of the drugs, which include Fosamax, Actonel or Didrocal, with an increased risk of fractures of the femur. Cases reports have been emerging of these unusual, or "atypical" fractures, "which is ironic given that they're taken to prevent fractures," Etminan says.

The study didn't prove cause and effect, just an association. It's also not clear how the fractures might be occurring. But Etminan says studies in animals suggest that, with long term use, the drugs can interfere with the bone remodelling process, "so they start making the bone more brittle rather than strong, or robust."

But findings from smaller studies in humans have been conflicting and left doctors and patients confused. The new study stands out for its sheer size. It included more than 200,000 women in Ontario, aged 68 and older, who were prescribed a bisphosphonate between 2002 and 2008.

Typical hip fractures occur at the upper top of the thigh bone. What makes these thigh bone fractures unusual is that they occur lower down from the hip, closer to the middle of the femur.

"Osteoporosis fractures are serious — we know they're associated with a huge cost to the health-care system," said the study's lead author Laura Park-Wyllie, a pharmaceutical safety and outcomes researcher at St. Michael's Hospital in Toronto

"Thigh bone fractures are also serious, because you do end up going into hospital, often require surgery and there can be delayed healing."

But, "the thigh fractures that we observed were much less common than the fractures that would normally occur with typical osteoporosis."

Up to 50 per cent of women older than 50 will suffer an osteoporosis-related fracture of the wrist, hip, spine or other bone during their lifetime, the Toronto researchers write in this week's issue of the Journal of the American Medical Association. One in five of these women who suffer a hip fracture will die within 12 months of their fracture.

For their study, researchers from St. Michael's Hospital and the Institute for Clinical Evaluative Sciences identified 205,466 women over age 68 prescribed bisphosphonates.

Of those, 716 — or 0.35 per cent — had a fracture of the femur.

The drugs lowered the risk of a hip fracture by about 25 per cent in women taking the drugs for five or more years.

"On average, the benefit of continuing treatment will outweigh the risks," Park-Wyllie said.

"But long-term use of the drugs may warrant reconsideration in patients who are at relatively low risk of fracture. If you're not at high-risk of an osteoporotic fracture, you could talk to your doctor about whether you should continue, or stop taking the drug," she said. "These treatments should be reserved for the women who need them."

Last year, the U.S. Food and Drug Administration warned patients and doctors about the possible risk of thigh bone fractures in patients taking bisphosphonates.

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If you or a loved one have taken Fosamax and have been injured as a result of Fosamax side effects such as osteonecrosis of the jaw or low energy femur fracture, contact the Fosamax lawyer of Ennis & Ennis, P.A. today. The Fosamax lawyers of Ennis & Ennis specialize in Fosamax lawsuits resulting from Fosamax side effects injuries. Ennis & Ennis, P.A. is a national mass tort litigation / drug litigation law firm with offices in Washington DC and throughout Florida. Call us today or fill out our free online case evaluation form.

Under no circumstances should you discontinue taking any medication, including Fosamax, without first consulting with your doctor.