Prior pneumococcal and influenza vaccinations and in-hospital outcomes for community-acquired pneumonia in elderly veterans.

Background: Studies of adults hospitalized for community-acquired pneumonia (CAP) reported better outcomes associated with prior pneumococcal vaccination (PV), suggesting potential additional benefits of PV in hospitalized CAP patients. Influenza (flu) vaccination (FV) could independently/additively improve CAP outcomes in hospitalized patients.

Objective: To examine the effect of prior PV and FV on in-hospital outcomes in elderly veterans hospitalized for CAP.

Design: Retrospective cohort study.

Setting And Patients: A total of 6,723 elderly veterans who were admitted to Veterans Affairs hospitals for CAP between October 1, 2002 and September 30, 2003.

Intervention: PV in the 5 years and FV in the 1 year before admission.

Measurements: The association of prior PV and/or FV with inpatient mortality and length of stay (LOS) (primary) and risk of any bacteremia and respiratory complications (secondary) were assessed using logistic regressions and generalized linear model, controlling for patient demographic and clinical characteristics.

Results: Prior PV alone was not associated with shortened LOS, or reduced risk of inpatient mortality or respiratory complications. Lower risk of bacteremia was associated with prior PV (odds ratio: 0.66; 95% confidence interval [CI]: 0.48-0.90). After adjusting for patients' characteristics, risk of inpatient mortality was not statistically significantly different across the vaccination groups, but having had both PV and FV before CAP admission was associated with a 10% reduction in LOS (95% CI: 0.86-0.95) compared to having had neither vaccinations.

Conclusion: Significant survival benefit and improved in-hospital outcomes may not be expected among CAP-hospitalized elderly patients with prior PV alone. However, having both PV and FV before CAP admission may reduce LOS.