People who take medication to reduce stomach acid seem to be at increased risk of developing pneumonia, the results of a population-based study suggest.

The findings apply to both proton pump inhibitors (PPIs) such as Nexium or Prevacid, for example, and to H2-receptor antagonists, which include popular products such as Pepcid and Zantac

While the effectiveness of acid-suppressive drugs in the treatment of heartburn and reflux disease is “excellent,” these agents seem to have some “significant drawbacks,” investigators write in this week’s Journal of the American Medical Association.

In the study, Dr. Robert J. F. Laheij from the University Medical Center St. Radboud in Nijmegen, the Netherlands and colleagues used information in a national primary care database to analyze pneumonia rates in individuals who did or did not use acid-suppressing drugs. The analysis included 364,683 Dutch subjects and 5551 first occurrences of pneumonia.

The incidence rate of pneumonia in acid-suppressive drug users was 2.45 per 100 persons per year, compared with 0.6 among people who didn’t take these types of drugs.

After factoring various adjustments, the team estimated that the risk of pneumonia was 89 percent higher for current users of PPIs and 63 percent higher for current users of H2-receptor antagonists, compared with past users of these agents.

“The increased risk for pneumonia is a problem for patients who are at increased risk for infection, especially because community-acquired pneumonia is potentially dangerous,” Laheij and colleagues note.

The results of this study are “noteworthy,” writes Dr. James C. Gregor from the University of Western Ontario in London, Ontario, Canada, in an editorial.

“If acid suppression causes some cases of pneumonia, it is reassuring that the risk is relatively small and that the complication in most cases is usually amenable to therapy,” he contends.

Nonetheless, Gregor reminds doctors that “concerns for patient safety should guide initial prescribing and perhaps more importantly, chronic use of even the most apparently benign drugs.”

SOURCE: Journal of the American Medical Association, October 27, 2004.