Background and aim: 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.
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Competing interests: Dr C. Henderson is an employee of Oxford PharmaGenesis Ltd, which has received funding from AstraZeneca R&D M�lndal, Sweden.
Funding: This study was funded by a research grant from AstraZeneca R&D Mölndal, Sweden.
- American Thoracic Society
- gastro-oesophageal reflux disease
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