title: Use of acid-suppressive drugs and risk of pneumonia: a systematic review and meta-analysis.
abstract: BACKGROUND
  Observational studies and randomized controlled trials have yielded inconsistent findings about the association between the use of acid-suppressive drugs and the risk of pneumonia. We performed a systematic review and meta-analysis to summarize this association.
  
  
  METHODS
  We searched three electronic databases (MEDLINE [PubMed], Embase and the Cochrane Library) from inception to Aug. 28, 2009. Two evaluators independently extracted data. Because of heterogeneity, we used random-effects meta-analysis to obtain pooled estimates of effect.
  
  
  RESULTS
  We identified 31 studies: five case-control studies, three cohort studies and 23 randomized controlled trials. A meta-analysis of the eight observational studies showed that the overall risk of pneumonia was higher among people using proton pump inhibitors (adjusted odds ratio [OR] 1.27, 95% confidence interval [CI] 1.11-1.46, I(2) 90.5%) and histamine(2) receptor antagonists (adjusted OR 1.22, 95% CI 1.09-1.36, I(2) 0.0%). In the randomized controlled trials, use of histamine(2) receptor antagonists was associated with an elevated risk of hospital-acquired pneumonia (relative risk 1.22, 95% CI 1.01-1.48, I(2) 30.6%).
  
  
  CONCLUSIONS
  Use of a proton pump inhibitor or histamine(2) receptor antagonist may be associated with an increased risk of both community- and hospital-acquired pneumonia. Given these potential adverse effects, clinicians should use caution in prescribing acid-suppressive drugs for patients at risk.
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Chun-Sick
authors.initials: CS
authors.lastname: Eom
authors.forename: Christie Y
authors.initials: CY
authors.lastname: Jeon
authors.forename: Ju-Won
authors.initials: JW
authors.lastname: Lim
authors.forename: Eun-Geol
authors.initials: EG
authors.lastname: Cho
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Park
authors.forename: Kang-Sook
authors.initials: KS
authors.lastname: Lee
mesh_terms: D000863:Antacids / Q000009:adverse effects*; D000897:Anti-Ulcer Agents / Q000009:adverse effects*; D017714:Community-Acquired Infections / Q000139:chemically induced / Q000453:epidemiology; D003428:Cross Infection / Q000139:chemically induced / Q000453:epidemiology; D004305:Dose-Response Relationship, Drug; D006635:Histamine H2 Antagonists / Q000009:adverse effects*; D006801:Humans; D011014:Pneumonia / Q000139:chemically induced* / Q000453:epidemiology; D054328:Proton Pump Inhibitors / Q000009:adverse effects*
chemical_list: D000863:Antacids; D000897:Anti-Ulcer Agents; D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors