Effects of annual influenza vaccination on mortality and hospitalization in elderly patients with ischemic heart disease: A nationwide population-based study

Objective: The effects of influenza vaccination on ischemic heart disease (IHD) patients remain controversial. The purpose of this study was to evaluate the effects of influenza vaccination on all-cause mortality and hospitalization for cardiovascular disease in elderly IHD patients. Methods: Elderly patients (> 65. years old) with IHD, including ischemic heart failure and coronary artery disease between January 1997 and September 2002 were identified by using the Taiwan National Health Insurance Research Database. The association between influenza vaccination and all-cause mortality and hospitalization due to cardiovascular disease was analyzed. Results: We included 5048 patients. During the influenza season, influenza vaccination was associated with a reduced risk of all-cause mortality [hazard ratio (HR), 0.42; 95% confidence interval (CI) 0.35-0.49] and hospitalization for cardiovascular disease (HR, 0.84; 95% CI, 0.76-0.93). During the non-influenza season, vaccination was associated with a reduced risk of mortality (HR, 0.78; 95% CI, 0.68-0.90) in elderly IHD patients. Conclusion: Influenza vaccination was associated with a reduced risk of all-cause mortality in elderly IHD patients throughout the whole year, as well as a reduced risk of hospitalization during the influenza season.