Use of proton pump inhibitors and H2 blockers and risk of pneumonia in older adults: a population-based case-control study

Purpose To examine whether use of proton pump inhibitors (PPIs) and H2 blockers is associated with increased pneumonia risk. Methods We conducted a population-based, nested case-control study within Group Health, an integrated healthcare delivery system. Among community-dwelling, immunocompetent adults aged 65-94, we identified presumptive cases of ambulatory and hospitalized community-acquired pneumonia in 2000-2003 from ICD-9 codes and validated them by medical record review (N=1125). Controls were selected, matched to cases on age, sex, and calendar year (N=2235). Current PPI or H2 blocker use was ascertained from computerized pharmacy records. Comorbid illnesses and other characteristics were ascertained by medical record review. Multivariable conditional logistic regression was used to examine the association between medication use and pneumonia risk. We conducted sensitivity analyses using only administrative and pharmacy data to assess how these results differed from our primary results. Results The prevalence of PPI or H2 blocker use was 21% (241/1125) for pneumonia cases and 16% (350/2235) for controls (adjusted odds ratio [OR] 1.03,95% CI 0.86-1.24, compared to nonuse). No increased risk was seen for recent initiation. The prevalence of PPI use was 12% (132/1125) for cases and 7% (160/2235) for controls (adjusted OR 1.13, 95% CI 0.88-1.44). Analyses using only administrative and pharmacy data yielded risk estimates farther from the null (adjusted OR 1.32, 95% CI 1.17-1.49, for current PPI use versus nonuse). Conclusions Use of PPIs and H2 blockers is not associated with increased pneumonia risk in older adults. The increased risk observed in some prior studies may reflect confounding. Copyright (C) 2010 John Wiley & Sons, Ltd.