The predominance of heartburn among asthma sufferers led many specialists to suspect that acid reflux could be a trigger for the coughing, wheezing and breathlessness of asthma.
In fact, it has become standard practice to prescribe heartburn medication to people with poorly controlled asthma, even if they don't have overt acid reflux symptoms.
But a new study of adults with inadequate asthma control without significant heartburn shows that heartburn medication does not help control their asthma symptoms. The study, conducted by the American Lung Association's Asthma Clinical Research Centers at 20 U.S. sites, is the most comprehensive to date. It demonstrated that participants who took esomeprazole (Nexium) had as many asthma episodes as participants who were given an inactive pill, or placebo. The findings will appear April 9, 2009, in the New England Journal of Medicine.
"This study goes against the idea that mild or silent acid reflux contributes to uncontrolled asthma," says Mario Castro, M.D., a Washington University pulmonary specialist at Barnes-Jewish Hospital who led the study in St. Louis. "It establishes that heartburn medications are not indicated for adults with uncontrolled asthma when they have mild or no symptoms of acid reflux."
However, Castro says prescription heartburn medication is still indicated for those with severe heartburn and poorly controlled asthma because it might improve asthma control in some of these patients.
The practice of prescribing heartburn medication to patients with poorly controlled asthma was a product of common sense - not only did asthma patients often suffer from heartburn, doctors had evidence that stomach acid traveling up the esophagus could get into the lungs and cause coughing. In addition, studies in laboratory animals showed that if the lower esophagus is exposed to acid, it could send nerve signals that loop back to the lungs and cause airway constriction.
But, past investigations into the potential benefit of heartburn medication for asthma control were inconclusive, showing either no effect or a small benefit.
The current study enrolled 412 patients who had poorly controlled asthma despite being treated with inhaled corticosteroids. But they had either no or very mild acid reflux symptoms. Each participant was randomly assigned to receive either 80 milligrams of esomeprazole or a placebo daily. Then for 24 weeks, they kept a daily record of their asthma symptoms. Every four weeks their lung function was tested, and they completed asthma questionnaires.