title: Gastroesophageal reflux and asthma in children: a systematic review.
abstract: BACKGROUND
  The relationship between gastroesophageal reflux disease (GERD) and asthma in children has been investigated; however, the nature of the association (if any) between these 2 conditions is unclear.
  
  
  OBJECTIVE
  We performed a systematic review of the literature to examine the association between GERD and asthma in children.
  
  
  METHODS
  A search of the medical literature was conducted by using PubMed and Embase (1966 through December 2008). Full-length articles in English that described at least 20 subjects younger than 18 years were included if they reported the prevalence of GERD (symptoms, pH studies, endoscopy/histology) in individuals with asthma or the prevalence of asthma in individuals with GERD. We calculated pooled odds ratios from studies that examined control groups, and we pooled prevalence estimates from all studies.
  
  
  RESULTS
  A total of 20 articles that described 5706 patients fulfilled the inclusion and exclusion criteria. Seventeen studies used objective methods for documenting reflux (eg, pH probe, contrast imaging, impedance, esophagogastroduodenoscopy), 2 studies relied on symptom-based questionnaires, and 1 study used diagnostic codes. Most studies (n = 19) examined the prevalence of GERD in 3726 individuals with asthma and reported highly variable estimates (19.3%-80.0%) and a pooled average of 22.8% with GERD symptoms, 62.9% of 789 patients with abnormal esophageal pH, and 34.8% of 89 patients with esophagitis. Only 5 studies included controls and enrolled 1314 case-patients with asthma and 2434 controls without asthma. The average prevalence of GERD was 22.0% in asthma cases and 4.8% in controls (pooled odds ratio: 5.6 [95% confidence interval: 4.3-6.9]).
  
  
  CONCLUSIONS
  There is a possible association between GERD and asthma in pediatric patients seen with asthma in referral settings. However, because of methodologic limitations of existing studies, the paucity of population-based studies, and a lack of longitudinal studies, several aspects of this association are unclear.
authors.affiliation: Section of Pediatric Gastroenterology, Hepatology, and Nutrition, Baylor College of Medicine, 6621 Fannin St, CCC 1010, Houston, TX 77030, USA. kthakkar@bcm.tmc.edu
authors.forename: Kalpesh
authors.initials: K
authors.lastname: Thakkar
authors.forename: Renu O
authors.initials: RO
authors.lastname: Boatright
authors.forename: Mark A
authors.initials: MA
authors.lastname: Gilger
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
mesh_terms: D000367:Age Factors; D001249:Asthma / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D012307:Risk Factors