Recurrent community-acquired pneumonia in patients starting acid-suppressing drugs.

BACKGROUND Several studies suggest that proton pump inhibitors (PPIs) and histamine 2-receptor antagonists (H2s) increase risk of community-acquired pneumonia. To test this hypothesis, we examined a prospective population-based cohort predisposed to pneumonia: elderly patients (> or =65 years) who had survived hospitalization for pneumonia. METHODS This study featured a nested case-control design where cases were patients hospitalized for recurrent pneumonia (> or =30 days after initial episode) and controls were age, sex, and incidence-density sampling matched but never had recurrent pneumonia. PPI/H2 exposure was classified as never, past, or current use before recurrent pneumonia. The association between PPI/H2s and pneumonia was assessed using multivariable conditional logistic regression. RESULTS During 5.4 years of follow-up, 248 recurrent pneumonia cases were matched with 2476 controls. Overall, 71 of 608 (12%) current PPI/H2 users had recurrent pneumonia, compared with 130 of 1487 (8%) nonusers (adjusted odds ratio [aOR] 1.5; 95% confidence interval [CI], 1.1-2.1). Stratifying the 608 current users according to timing of PPI/H2 initiation revealed incident current-users (initiated PPI/H2 after initial pneumonia hospitalization, n=303) bore the entire increased risk of recurrent community-acquired pneumonia (15% vs 8% among nonusers, aOR 2.1; 95% CI, 1.4-3.0). The 305 prevalent current-users (PPI/H2 exposure before and after initial community-acquired pneumonia hospitalization) were equally likely to develop recurrent pneumonia as nonusers (aOR 0.99; 95% CI, 0.63-1.57). CONCLUSION Acid-suppressing drug use substantially increased the likelihood of recurrent pneumonia in high-risk elderly patients. The association was confined to patients initiating PPI/H2s after hospital discharge. Our findings should be considered when deciding to prescribe these drugs in patients with a recent history of pneumonia.