Gastroesophageal reflux and asthma: can the paradox be explained?

The reported effects of asthma on gastroesophageal reflux (GER), effects of GER on asthma and the effects of antireflux therapy on asthma are conflicting. The purpose of this paper is to review the evidence for a relationship between the two conditions.

A search of the MEDLINE 1966 to 1999 database, combining the terms GER and asthma, was used to identify studies of the effects of acid perfusion of the esophagus, the physiological equivalent of GER and the effects of both medical and surgical antireflux therapy on asthma. Bibliographies of the identified papers were also reviewed.

The collected evidence suggests that GER causes asthma symptoms but has minimal effects on pulmonary function. Both medical and surgical antireflux therapy can improve asthma symptoms and asthma medication requirements without improving pulmonary function. The paradox of GER causing symptoms without affecting pulmonary function may be because of the retrosternal discomfort that accompanies GER increases minute ventilation and respiratory sensation.

Despite an extensive body of literature, many questions remain about the relationship between GER and asthma. A review of the data suggests a strong association between the two conditions, and that GER worsens asthma symptoms without affecting pulmonary function. Asymptomatic GER does not worsen asthma. Antireflux therapy may have a role in asthma patients with symptomatic GER, possibly being most beneficial for those with reflux-associated respiratory symptoms. Unfortunately, many studies contain flaws such as a lack of controls and small sample sizes. Further properly designed controlled trials, including ones that measure the effects of GER and antireflux therapy on quality of life, are needed to understand better the role of GER in asthma.