A study in Finland confirms that many adults with asthma have gastroesophageal reflux disease (GERD) and that many of these persons do not have the classic GERD symptoms. However, the role of GERD as an asthma trigger has not been clearly defined.
Kiljander and Laitinen studied 90 adults who had asthma. Abnormal acid reflux into the distal esophagus was documented by 24-hour esophageal pH monitoring in 32 (36%) of the participants. The typical GERD symptoms were absent in 8 (25%) of these patients. The overall incidence of typical symptoms in the study population was 52%.
There was no correlation between esophageal pH and forced expiratory volume in 1 second, which the authors say may be attributable to the complexity of the pathophysiology of GERD.
In an accompanying editorial, Harding notes that an increased pressure gradient between the thorax and abdomen may increase the risk of GERD in patients with asthma. Other predisposing factors may include hiatal hernia and the effects of some asthma medications. Reflux may trigger asthma by a variety of mechanisms, such as a vagally mediated reflex, a local axonal reflex, heightened bronchial reactivity, microaspiration, and neurogenic inflammation.
Harding does not believe that all patients with asthma should undergo esophageal pH monitoring. Although studies indicate that antireflux therapy can reduce asthma symptoms in some patients, it is difficult to predict which patients would benefit. Patients who might be expected to respond include those with regurgitation, nocturnal asthma, nonallergic asthma, or difficult-to-control asthma. However, since these "predictors" have not been validated in larger studies, a reasonable strategy would be to give a 3-month empiric trial of a proton pump inhibitor.