Gastroesophageal reflux and asthma: Can the paradox be explained?
BACKGROUND AND OBJECTIVE: 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.
DESIGN: 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.
MAIN RESULTS: 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
CONCLUSIONS: 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.