The association was found among persons with at least one other risk factor for hip fracture, suggesting that acid inhibition may be associated with fracture risk primarily among people already at risk for osteoporosis.
The researchers explain that acid suppressing medications may increase fracture risk by decreasing calcium absorption; this can decrease bone strength. Decreased calcium absorption with acid suppressing medications has been demonstrated in some small experimental studies.
“Acid inhibitors are among the most commonly used medications in the United States" said the study’s lead investigator, Douglas Corley, MD, PhD, with the Kaiser Permanente Division of Research in Oakland, CA. “So it’s important to better understand if there are long-term effects of medication use.”
These findings extend prior studies in Canada and the United Kingdom that evaluated acid inhibition and fracture risk. However, previous studies also found increased risk for other drugs not clearly associated with fracture risk such as aspirin, nonsteroidal anti-inflammatory drugs and antidepressants, which raised concerns about confounding in those evaluations. These findings were not present in the current study.
“People who need acid suppressing medications should continue taking them,” said the researchers. “But we do advise vigilance in prescribing these medications to people with clear reasons for treatment and at the lowest effective dose.” Gastric acid inhibitors are medications that reduce the production of stomach acid. They are different from antacids, which act on stomach acid after it has been produced and released into the stomach.
Gastric acid inhibitors are medications that reduce the production of stomach acid. They are different from antacids, which act on stomach acid after it has been produced and released into the stomach.
Gastric acid inhibitors are used to treat conditions such as stomach ulcers and reflux disease (heartburn). They are also sometimes used to prevent stomach damage in people at high risk for ulcers.
The researchers examined both H2-receptor blockers and proton pump inhibitors. H2-receptor blockers are a type of antihistamine. Histamine (in addition to its well-known effects in colds and allergies) stimulates the stomach to produce more acid. The proton pump inhibitors, which are more potent acid reducing medications than H2-receptor blockers, directly block the “proton pump” enzymes in the stomach that make stomach acid.
Researchers identified 33, 753 hip fracture cases and 130, 471 controls. Patients with hip fractures were more likely to have previously received two or more years of treatment with proton pump inhibitors or H2-receptors than controls. Higher doses were associated with an increasing risk of fracture, but the fracture risk decreased after medications were stopped, returning to normal in people who had not used the medications for at least two years. The increased risk was present only among people with at least one other risk factor for fracture, such as kidney disease or steroid use. People with risk factors for hip fracture should discuss with their physician whether they are getting enough calcium and vitamin D, noted the researchers.
Additional researchers on the study include Ai Kubo, PhD; Wei Zhao, MPH; Charles Quessenberry, PhD, all with the Kaiser Permanente Division of Research. The research was funded by a Kaiser Permanente Community Benefits Grant.