Effect of Influenza Vaccination Against Postoperative Pneumonia and Mortality for Geriatric Patients Receiving Major Surgery: A Nationwide Matched Study

Background. Limited information is available on the association between influenza vaccination and postoperative outcomes. Methods. Using Taiwan's National Health Insurance Research Database reimbursement claims data from 2008-2013, we conducted a matched cohort study of 16 903 patients aged >66 years who received influenza vaccinations and later underwent major surgery. Using a propensity score matching procedure adjusted for sociodemographic characteristics, medical condition, surgery type, and anesthesia type, 16 903 controls who underwent surgery but were not vaccinated were selected. Logistic regressions were used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for postoperative pneumonia and in-hospital mortality associated with influenza vaccination. Results. Patients who received preoperative influenza vaccination had a lower risk of postoperative pneumonia (OR, 0.60; 95% CI, .56-.64) and in-hospital mortality (OR, 0.46; 95% CI, .39-.56), compared with unvaccinated patients, in both sexes and every age group. Vaccinated patients who underwent surgery also had a decreased risk of postoperative intensive care unit admission (OR, 0.56; 95% CI, .53-.60), shorter hospital stays (P < .0001), and lower medical expenditures (P < .0001) than nonvaccinated controls. Conclusions. Vaccinated geriatric patients who underwent surgery had lower risks of pneumonia and in-hospital mortality, compared with unvaccinated patients who underwent similar major surgeries. Further studies are needed to explain how preoperative influenza vaccination improves perioperative outcomes.