Impact of seasonal variation on hospital admission and in-hospital mortality of acute cardiovascular diseases: a contemporary nationwide database study

Purpose: Whether acute cardiovascular diseases (CVDs), such as acute heart failure (AHF), acute myocardial infarction (AMI), and acute aortic dissection (AAD), have distinct seasonal variations in the number of hospitalizations and in-hospital mortality was investigated using a nationwide database in Japan.

Methods: The hospitalized patients with AHF, AMI, and AAD between April 2012 and March 2020 were identified. Multilevel mixed-effects logistic regression was conducted and adjusted odds ratio (aOR) was calculated. Also, the Poisson regression model was conducted to calculate the peak-to-trough ratio (PTTR) with peak month.

Results: Patients identified were as follows: 752,434 AHF patients (median age, 82 years; male, 52.2%), 346,110 AMI patients (median age, 71 years; male, 72.2%), and 118,538 AAD patients (median age, 72 years; male, 58.0%). The monthly proportion of hospitalized patients was the highest in winter and the lowest in summer in all three diseases. Based on aOR, 14-day mortality was the lowest in spring for AHF, summer for AMI, and spring for AAD. Furthermore, the PTTRs with peak month were 1.24 for AHF in February, 1.34 for AMI in January, and 1.33 for AAD in February.

Conclusions: A clear seasonal pattern was observed in the number of hospitalizations and in-hospital mortality of all acute CVDs, independent of confounders.