Impact of the pneumococcal vaccine on long-term morbidity and mortality of adults at high risk for pneumonia

Abstract

Background: There is debate surrounding the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV). We determined whether PPV was associated with reduced mortality or additional hospitalization for vaccine-preventable infections in patients previously hospitalized for community-acquired pneumonia (CAP).

Methods: From 2000 through 2002, adults with CAP admitted to the hospital in Edmonton, Alberta, Canada, were enrolled in a population-based cohort. Postdischarge outcomes during 5 years were ascertained using administrative databases. The primary outcome was the composite of all-cause mortality or additional hospitalization for vaccine-preventable infections. Proportional hazards analysis was used to determine the association between PPV use and outcomes.

Results: A total of 2950 patients were followed up for a median of 3.8 years. The mean patient age was 68 years; 52% were male. One-third (n = 956) received PPV: 667 (70%) before and 289 (30%) during hospitalization. After discharge, 1404 patients (48%) died, 504 (17%) were admitted with vaccine-preventable infections, and 1626 (55%) reached the composite outcome of death or infection. PPV was not associated with reduced risk of the composite outcome (589 [62%] vs 1037 [52%] for those unvaccinated; adjusted hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.79-1.04). Results were not altered in sensitivity analyses using propensity scores (adjusted HR, 0.91; 95% CI, 0.79-1.04), restricting the sample to patients 65 years or older (adjusted HR, 0.90; 95% CI, 0.77-1.04), or considering only those who received PPV at discharge (adjusted HR, 0.84; 95% CI, 0.71-1.00).

Conclusions: One-half of patients discharged from the hospital after pneumonia die or are subsequently hospitalized with a vaccine-preventable infection within 5 years. PPV was not associated with a reduced risk of death or hospitalization. Better pneumococcal vaccination strategies are urgently needed.