Popular heartburn medications may significantly increase the risk of suffering a disabling broken hip when taken over the long term, Canadian doctors say, and the drugs may be being prescribed inappropriately.

Proton pump inhibitors, or PPIs, such as Prilosec, Nexium and Prevacid, constitute class of drugs commonly prescribed for peptic ulcers and reflux, and they are often taken for years. In 2004, 12.4 million prescriptions were written for the drugs in Canada, according to the Canadian Agency for Drugs and Technologies in Health.

In Tuesday's issue of the Canadian Medical Association Journal, Dr. William Leslie, director of Manitoba's bone density program, and his colleagues find that taking PPIs for seven years or more nearly doubles the risk of an osteoporosis-related fracture.

Hip fractures can be severe, leading to death in about 20 per cent of cases. The number of Canadians who suffer the injury is predicted to increase to more than 88,000 in 2041, up from 23,375 in 1993-1994, an earlier study suggested.

There was also an increased risk of hip fracture after taking the heartburn medications for five years, Leslie's research team found after analyzing health databases to compare fracture rates among people over age 50 who had similar states of health.

While there is no concern for short-term use, the message of the study is important for all physicians, said Leslie, who also works in the departments of internal medicine and radiology at the University of Manitoba.

"In the case of patients who use proton pump inhibitors, this equilibrium" — weighing the risks against the benefits of taking the drugs — "should be reconsidered with knowledge of the mounting, yet incomplete, evidence suggesting that proton pump inhibitors increase the risk of fracture," physician David Goltzman of Montreal's Royal Victoria Hospital writes in a commentary article accompanying the research.

For people with bleeding ulcers, the benefits outweigh the risks of fracture, Goltzman writes. But family physicians should be wary of prescribing PPIs in the long term for minor gastrointestinal discomfort, Goltzman told CBC News.

Over-the-counter drugs suggested

Someone with very mild heartburn may be prescribed a proton pump inhibitor when they could find relief by switching to Tums or Zantac, said the study's lead investigator, Dr. Laura Targownik, a gastroenterologist at the University of Manitoba.

While the researchers tried to correct for many factors, they were unable to consider bone density measurements, which could affect the interpretation of the results.

As for how PPIs may increase the risk, the drugs block the production and secretion of stomach acids that are thought to be important for calcium absorption. Poor absorption of calcium could lead to more fractures, but more proof is needed to test the idea, the commentators said.

In 2006, a large British study also concluded that PPIs increase the risk of a broken hip.

That study concluded the risk increased after only a year of taking the drugs, based on data from several times more patients with hip fractures than in Leslie's study.

The apparent discrepancy in how long it takes before the risk appears could be related to the difference in number of patients studied, but is a clinically important issue that needs to be resolved, Goltzman writes.