title: Acid-suppressive medication use and the risk for hospital-acquired pneumonia.
abstract: BACKGROUND
  The use of acid-suppressive medication has been steadily increasing, particularly in the inpatient setting, despite lack of an accepted indication in the majority of these patients.
  
  
  OBJECTIVE
  To examine the association between acid-suppressive medication and hospital-acquired pneumonia.
  
  
  METHODS
  Prospective pharmacoepidemiologic cohort study. All patients who were admitted to a large, urban, academic medical center in Boston, Massachusetts, from January 2004 through December 2007; at least 18 years of age; and hospitalized for 3 or more days were eligible for inclusion. Admissions with time spent in the intensive care unit were excluded. Acid-suppressive medication use was defined as any order for a proton-pump inhibitor or histamine(2) receptor antagonist. Traditional and propensity-matched multivariable logistic regression were used to control for confounders.
  
  
  METHODS
  Incidence of hospital-acquired pneumonia, defined via codes from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), in patients exposed and unexposed to acid-suppressive medication.
  
  
  RESULTS
  The final cohort comprised 63 878 admissions. Acid-suppressive medication was ordered in 52% of admissions and hospital-acquired pneumonia occurred in 2219 admissions (3.5%). The unadjusted incidence of hospital-acquired pneumonia was higher in the group exposed to acid-suppressive medication than in the unexposed group (4.9% vs 2.0%; odds ratio [OR], 2.6; 95% confidence interval [CI], 2.3-2.8). Using multivariable logistic regression, the adjusted OR of hospital-acquired pneumonia in the group exposed to acid-suppressive medication was 1.3 (95% CI, 1.1-1.4). The matched propensity-score analyses yielded identical results. The association was significant for proton-pump inhibitors (OR, 1.3; 95% CI, 1.1-1.4) but not for histamine(2) receptor antagonists (OR, 1.2; 95% CI, 0.98-1.4).
  
  
  CONCLUSIONS
  In this large, hospital-based pharmacoepidemiologic cohort, acid-suppressive medication use was associated with 30% increased odds of hospital-acquired pneumonia. In subset analyses, statistically significant risk was demonstrated only for proton-pump inhibitor use.
authors.affiliation: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA. sherzig@bidmc.harvard.edu
authors.forename: Shoshana J
authors.initials: SJ
authors.lastname: Herzig
authors.forename: Michael D
authors.initials: MD
authors.lastname: Howell
authors.forename: Long H
authors.initials: LH
authors.lastname: Ngo
authors.forename: Edward R
authors.initials: ER
authors.lastname: Marcantonio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D003428:Cross Infection / Q000453:epidemiology*; D004363:Drug Utilization; D005260:Female; D006635:Histamine H2 Antagonists / Q000627:therapeutic use*; D006760:Hospitalization; D006801:Humans; D038801:International Classification of Diseases; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017891:Pharmacoepidemiology; D011014:Pneumonia / Q000453:epidemiology*; D011446:Prospective Studies; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*; D015203:Reproducibility of Results; D012306:Risk; D055815:Young Adult
chemical_list: D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors