The association between gastro-oesophageal reflux disease and asthma: a systematic review.
OBJECTIVE
Gastro-oesophageal reflux disease (GORD) has been linked to a number of extra-esophageal symptoms and disorders, primarily in the respiratory tract. This systematic review aimed to provide an estimate of the strength and direction of the association between GORD and asthma.


METHODS
Studies that assessed the prevalence or incidence of GORD in individuals with asthma, or of asthma in individuals with GORD, were identified in Medline and EMBASE via a systematic search strategy.


RESULTS
Twenty-eight studies met the selection criteria. The sample size weighted average prevalence of GORD symptoms in asthma patients was 59.2%, whereas in controls it was 38.1%. In patients with asthma, the average prevalence of abnormal oesophageal pH, oesophagitis and hiatal hernia was 50.9%, 37.3% and 51.2%, respectively. The average prevalence of asthma in individuals with GORD was 4.6%, whereas in controls it was 3.9%. Pooling the odds ratios gave an overall ratio of 5.5 (95% CI 1.9-15.8) for studies reporting the prevalence of GORD symptoms in individuals with asthma, and 2.3 (95% CI 1.8-2.8) for those studies measuring the prevalence of asthma in GORD. One longitudinal study showed a significant association between a diagnosis of asthma and a subsequent diagnosis of GORD (relative risk 1.5; 95% CI 1.2-1.8), whereas the two studies that assessed whether GORD precedes asthma gave inconsistent results. The severity-response relationship was examined in only nine studies, with inconsistent findings.


CONCLUSIONS
This systematic review indicates that there is a significant association between GORD and asthma, but a paucity of data on the direction of causality.
Section of Gastroenterology, Houston Department of Veterans Affairs Medical Center, and Department of Medicine, Baylor College of Medicine, Houston, Texas, USA.
B D
BD
Havemann
C A
CA
Henderson
H B
HB
El-Serag
D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008991:Monitoring, Physiologic; D015995:Prevalence; D012720:Severity of Illness Index