HMN 2026: How Out-of-hospital cardiac arrest incidence rises on postholiday weekdays

In South Korea, postholiday weekdays are associated with a significantly increased incidence of out-of-hospital cardiac arrest, according to a study published online March 6 in JAMA Network Open.

Min-Su Cha, M.D., from the Catholic Kwandong University College of Medicine in Incheon, South Korea, and colleagues quantified the incidence of out-of-hospital cardiac arrest on a postholiday weekday in South Korea in a nationwide cohort study. The out-of-hospital cardiac arrest incidence rate ratio (IRR) comparing a postholiday weekday to baseline weekdays was assessed as the primary outcome.

The researchers found that 49,199 cases occurred on a postholiday weekday and 154,272 occurred on baseline weekdays among the 203,471 adult participants. Compared with baseline weekdays, on a postholiday weekday, the daily out-of-hospital cardiac arrest incidence was significantly higher (median, 88 versus 80 cases; IRR, 1.09). Increased vulnerability was seen among adults older than 65 years, individuals with cardiac cause, and those presenting with nonshockable rhythms (IRRs, 1.03, 1.02, and 1.03, respectively). There was a clear dose-response association. Significant associations were not seen after single-day holidays, but were seen after two-day holidays, three-day holidays, and holidays of four days or more (IRR, 1.10, 1.09, and 1.10, respectively). Higher out-of-hospital cardiac arrest incidence was seen in association with weekend or mixed holidays (IRRs, 1.09 and 1.10, respectively), but not public and temporary holidays.

“Theories include changes in sleep patterns and changes in your circadian rhythm going from a weekend back to a work week, the stress associated with that,” Matt Pierce, M.D., director of the cardiac intensive care unit at North Shore University Hospital in Manhasset, New York, said in a statement.

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