Abstract 10968: Seasonal Variations in In-Hospital Mortality Caused by Acute Cardiovascular Diseases in Japan from JROAD-DPC Dataset

Introduction: Previous studies have shown that the incidence of acute cardiovascular diseases (CVDs) increases in winter. However, there is few research regarding seasonal changes of the in-hospital mortality and its relationship with the detailed conditions. Hypothesis: We assessed whether the acute CVDs have related seasonal trends regarding of hospitalized-patients number and in-hospital mortality using a national-wide Japanese registry of all cardiac and vascular datasets-Diagnostic Procedure Combination (JROAD-DPC). Methods: Based on International Classification of Diseases, Tenth Revision (ICD-10) code, we identified the hospitalized patients with acute CVDs; acute myocardial infarction (AMI, ICD10:I20), acute heart failure (AHF, ICD10:I50+additional code 30101/30102), and acute aortic dissection (AAD, ICD10:I710) between April 2012 and March 2020. Season was distinguished into four categories (Spring: March-May, Summer: June-August, Fall: September-November, and Winter: December-February). Univariate multilevel mixed-effects logistic regression with institution as a random variable was conducted. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated. Result: 1,644,135 patients with acute CVDs (age: 76.2 ± 13.5, male: 57.7 %) were identified. The number of hospitalized patients was the most in Winter among the seasons (30.4%). Using Spring as a reference, ORs (95% CI) of in-hospital mortality in Summer were 0.97 (0.95, 0.98) for all, 0.97 (0.94, 0.99) for age younger than 75, 0.98 (0.96, 0.99) for male, and 0.95 (0.93, 0.97) for female. In contrast, those in Winter was 1.03 (1.02,1.04) for all, 1.02 (0.99, 1.05) for age younger than 75, 1.05 (1.03, 1.07) for male, and 1.01 (0.99, 1.03) for female. Furthermore, in each diagnosis, those in Summer were 0.81 (0.79, 0.85) for AMI and 1.06 (1.02, 1.09) for AHF and 0.77 (0.73, 0.82) for AAD, whereas those in Winter were 1.04 (1.01, 1.08) for AMI, 1.01 (0.98, 1.04) for AHF, and 0.94 (0.89, 0.99) for AAD. Conclusions: A clear seasonal pattern was found in hospitalized patients with acute CVDs in a recent large-scale nationwide dataset; however, different seasonal trends of in-hospital mortality were found in younger, female, and AHF or AAD patients.