Influenza-Associated Hospitalizations and Risk of Subsequent Heart Failure Hospital Admissions: A 20-Year Territorywide Registry Study in Hong Kong, China.

Little is known about the risk of hospitalization for cardiovascular disease after influenza infection in younger adults. In a territorywide Hong Kong, China, study using clinical registry data for 1997-2017, we examined the association between influenza-associated hospitalizations and the risk of subsequent hospitalization for heart failure (HHF) in 3 age groups: 18-44 years, 45-65 years, and >65 years. Exposure was defined as any infection with influenzavirus as a primary principal diagnosis for hospitalization, whereas the nonexposed control group comprised persons with hospitalizations for elective orthopedic surgery. Logistic regression was used to determine the risk of HHF within 12 months of hospital discharge for the exposed group versus the nonexposed group. Results showed that influenza-associated hospitalization in the preceding 12 months was associated with increased risk of subsequent HHF in all age groups (all P values < 0.001). Notably, the age group 18-44 years was found to have the highest elevated risk of HHF (adjusted odds ratio = 14.90, 95% confidence interval: 4.48, 49.58). In view of the relatively small number of subsequent HHF episodes in this age group, future studies are needed to confirm the elevated risk in this group and to explore the role of age in the relationship between influenza-associated hospitalization and subsequent HHF.