Influenza-Associated Hospitalizations for Cardiovascular Diseases in the Tropics

Influenza is a major cause of mortality and morbidity. We aimed to examine the influenza-associated hospitalization rates and proportions for cardiovascular disease (CVD) in tropical Singapore. Hospital admissions for ischemic heart disease (IHD), congestive heart failure (CHF), and overall CVD were obtained from the national inpatient database for the period of 2010-2014. We used, as the key indicator of influenza virus activity, the overall proportion of specimens from outpatients with influenza-like illness in the community that tested positive for influenza as part of the national influenza surveillance program. The annual influenza-associated hospitalization rates per 100,000 person-years ranged from 9.5 to 12.2 for IHD, 7.7 to 9.1 for CHF, and 15.8 to 19.2 for overall CVD. The influenza-associated hospitalization rates increased with increasing age. Influenza was significantly associated with excess hospitalizations in elderly persons aged ≥80 years, with an excess hospitalization rate per 100,000 person-years of 242.7 for IHD (P = 0.02), 271.8 for CHF (P = 0.01), and 497.2 for overall CVD (P < 0.001). In the tropics, influenza accounts for excess cardiovascular-related hospitalizations, especially in the elderly.