Acid reflux link to asthma in doubt: heartburn drugs may not help patients with severe attacks.

Taking heartburn drugs doesn't reduce severe attacks among asthma patients, researchers report in the April 9 New England Journal of Medicine. The findings cast doubt on a long-held assumption that even unnoticed acid reflux exacerbates asthma.

Many doctors prescribe proton pump inhibitors such as Nexium or Prilosec--used for acid reflux, commonly called heartburn--for asthma patients. Earlier studies have suggested that acid reflux worsens asthma by irritating nerves that serve the windpipe and esophagus or by sending stomach acid up the esophagus and down into the windpipe, says study coauthor Robert Wise of Johns Hopkins University in Baltimore.

Doctors have reasoned that treating even silent acid reflux, which causes no outward symptoms, would thus ease the bronchial constriction and coughing of asthma attacks.

In the new study, the team recruited people with asthma that was poorly controlled by standard drugs but excluded people who reported regular discomfort from acid reflux. Tests for acid in the esophagus showed that about 40 percent of the participants in both the group treated with heartburn drugs and the placebo group had silent acid reflux.

Nevertheless, over a period of nearly six months, the rate of severe asthma attacks was no different between the people getting the drugs or placebos.

"This was quite unexpected," says study collaborator Nicola Hanania of Baylor College of Medicine in Houston.

Wise estimates that 15 to 65 percent of people with asthma get the drugs on the assumption it will help their asthma.