Seasonal Variation in the Incidence of In-Hospital Cardiac Arrest

BACKGROUND Seasonal variation in cardiovascular outcomes, including out-of-hospital cardiac arrest, has been described. OBJECTIVES This study aimed to investigate seasonal differences in the incidence of in-hospital cardiac arrest (INCA) and associated mortality. METHODS Using National Inpatient Sample data from 2005 to 2019, we determined the incidence of INCA in 4 seasons. The primary objective was to evaluate overall seasonal trends in the incidence of INCA and trends stratified by sex, age, and region. The secondary aim was to determine common causes of admission that led to INCA, differences in those with shockable vs nonshockable INCA, independent predictors of INCA, and seasonal variation in INCA-related in-hospital mortality and length of stay. RESULTS A consistent winter peak was observed in the incidence of INCA in both male and female patients over the years in all age groups except young (<45 years) and in all regions. In 2019, both unadjusted and risk-adjusted odds of INCA were higher (OR: 1.13; P < 0.001; adjusted OR: 1.08; P 1/4 0.033) in winter than in summer. Patients with shockable INCA were mainly admitted for cardiac and those with nonshockable INCA for noncardiac conditions. No seasonal variation was observed in in-hospital mortality after INCA. Therefore, seasonal variation exists, with a higher INCA event rate in winter than summer. CONCLUSIONS Improving insights into factors that influence the higher INCA event rate during winter may help with proper resource allocation, development of strategies for early recognition of patients vulnerable to INCA, and closer monitoring and optimization of care to prevent INCA and improve outcomes.(c) 2023 by the American College of Cardiology Foundation.