Background and aim: Gastroesophageal reflux disease (GERD) 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 GERD and asthma.
Methods: Studies that assessed the prevalence or incidence of GERD in individuals with asthma, or of asthma in individuals with GERD, were identified in Medline and EMBASE via a systematic search strategy.
Results: Twenty-eight studies met our selection criteria. The sample-size weighted average prevalence of GERD symptoms in asthma patients was 59.2%, while in controls it was 38.1%. In patients with asthma, the average prevalence of abnormal esophageal pH, esophagitis and hiatal hernia was 50.9%, 37.3% and 51.2%, respectively. The average prevalence of asthma in individuals with GERD was 4.6%, while 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 GERD symptoms in individuals with asthma and 2.3 (95% CI: 1.8-2.8), for those studies measuring the prevalence of asthma in GERD. One longitudinal study showed a significant association between a diagnosis of asthma and subsequent diagnosis of GERD (RR: 1.5; 95% CI: 1.2-1.8), while the two studies that assessed whether GERD 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 GERD and asthma, but a paucity of data on the direction of causality.
- gastroesophageal reflux
- systematic review
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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.