CHICAGO -- Long-term use of popular antiheartburn drugs such as Nexium and Prevacid increase the risk of hip fractures in adults over 50, perhaps because the drugs inhibit calcium absorption, researchers said yesterday.
The class of drugs -- called proton pump inhibitors -- shut down stomach acid production, providing relief for millions of patients who suffer from acid-related stomach problems, including ulcers and gastro-esophageal reflux.
But the researchers at the University of Pennsylvania School of Medicine found that a longterm reduction in acid levels may carry somewhat more risk than previously recognized.
Their study of nearly 150,000 Britons older than 50 found that those undergoing antiheartburn drug therapy had a 44 percent greater risk of hip fracture than those who were not taking the drugs.
Dr. Yu-Xiao Yang, the lead author of the study, estimated that taking a regular dose of the heartburn drugs for at least a year was associated with one additional hip fracture annually per every 1,262 people.
The study showed the longer the drugs were used and the higher the dosage, the greater the risk of fracturing a hip. But in many cases, doctors prescribe the drugs for two months or less.
The study's authors termed the increased bone risk significant, especially among those taking higher dosages, and urged further research to identify the underlying mechanism at work.
Some previous research has shown the drugs may reduce the body's ability to absorb calcium, which is needed to maintain healthy bones, and may decrease bone density in some patients, the study said.
"At this point, physicians should be aware of this potential association when considering [proton pump inhibitor] therapy and should use the lowest effective dose for patients with appropriate indications," said Yang.
The report on the study, published in this week's issue of the Journal of the American Medical Association, also said elderly patients requiring long-term and high-dose drug therapy should consider increasing calcium intake.
But Dr. David Forcione, a gastroenterologist at Massachusetts General Hospital, said he did not feel the evidence was strong enough to change how doctors prescribe proton pump inhibitors. For instance, he said the study did not weigh the potential risks of the drugs against the benefits, such as possibly reducing esophageal cancer by reducing the longterm damage from stomach acid.
"It's interesting and warrants further study," he said. "At a glance, it's unlikely to significantly modify our use of PPIs. They're a very safe group of medications overall."
Hip fractures are a curse for the elderly and are difficult to heal, especially for those with declining bone density. One in five who suffer a hip fracture die within a year, the study said.
Some of the brand-name versions of the heartburn- and ulcer-fighting drugs include
Liz Kowalczyk of the Globe staff contributed to this report.