title: Meta-analysis: proton pump inhibitor use and the risk of community-acquired pneumonia.
abstract: BACKGROUND
  Observational studies examining the association between proton pump inhibitor (PPI) use and risk of community-acquired pneumonia are conflicting.
  
  
  OBJECTIVE
  To assess systematically the association between risk of community-acquired pneumonia and PPI use in adults.
  
  
  METHODS
  We searched MEDLINE, EMBASE and CINAHL databases between 1988 and January 2010. Two reviewers independently selected studies based on eligibility criteria and extracted data. Included studies evaluated adults (> or =18 years) who took PPIs as an out-patient. The primary outcome was community-acquired pneumonia. Only observational studies with a comparison arm were included.
  
  
  RESULTS
  Over 2600 citations were reviewed. Six studies were included. All were nested case-control studies. Meta-analysis found an increased risk of community-acquired pneumonia associated with PPI use [OR 1.36 (95% CI 1.12-1.65)]; significant heterogeneity remained (I(2) 92%, P < 0.001). In exploratory subgroup analysis, short duration of use was associated with an increased odds of community-acquired pneumonia [OR 1.92 (95% CI 1.40-2.63), I(2) 75%, P = 0.003], whereas chronic use was not [OR 1.11 (95% CI 0.90-1.38), I(2) 91%, P < 0.001], a significant interaction (P < 0.005).
  
  
  CONCLUSIONS
  Heterogeneity precluded interpretation of the summary statistic. Exploratory analysis revealed that duration of PPI use may impact the risk of community-acquired pneumonia, a finding that should be explored in future studies.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada. johnsj48@mcmaster.ca <johnsj48@mcmaster.ca>
authors.forename: J
authors.initials: J
authors.lastname: Johnstone
authors.forename: K
authors.initials: K
authors.lastname: Nerenberg
authors.forename: M
authors.initials: M
authors.lastname: Loeb
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000897:Anti-Ulcer Agents / Q000009:adverse effects* / Q000627:therapeutic use; D016022:Case-Control Studies; D017714:Community-Acquired Infections / Q000139:chemically induced*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000139:chemically induced*; D054328:Proton Pump Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D012307:Risk Factors; D055815:Young Adult
chemical_list: D000897:Anti-Ulcer Agents; D054328:Proton Pump Inhibitors