Associations between the standard deviation of apparent temperature and sudden cardiac arrest during the Taipei Marathon, 2013–2024

Background Climate change has led to a discernible increase in the intensity of extreme weather events, contributing to growing public health concerns regarding temperature-related mortality and morbidity. Recently, there has been an increase in the number of sudden cardiac arrests (SCAs) occurring during annual Taipei Marathon events compared with previous years. This study aimed to explore the correlation between weather conditions and SCA risk in runners. Methods This retrospective observational study used data from the Taipei Marathon event held between 2013 and 2024 in Taiwan. We examined the relationship between the SCAs and weather conditions for each year using a Poisson regression model. Results Among the 95,866 full- and 220,580 half-marathoners, all SCAs occurred in Taiwanese runners. There were three SCAs in male marathoners (median age, 50 years). In half-marathon runners, 10 SCAs occurred (median age, 30 years), including nine males and one female. Each 1 °C increase in the standard deviation of apparent temperature (AT) over the 7-day time window (lag 0–6) was associated with an SCA incidence rate that was 6.63 times as high on race day (IRR = 6.63, 95% profile likelihood CI 1.85–52.11; LRT p < 0.001). The incidence rate was significantly higher during half-marathons than during full marathons (4.53 versus 3.13 per 100,000 participants) and among men than among women (5.17 versus 1.18 per 100,000). The highest proportion of SCA (61.5%) occurred in the final quarter of the race. Bystander-administered cardiopulmonary resuscitation (CPR) was provided in all SCA events (100%). Automated external defibrillator shocks were delivered to 11 of 13 runners (84.6%). All 13 runners (100%) achieved return of spontaneous circulation in the field. Conclusion Greater short-term AT variability was associated with a higher incidence of SCA during Taipei Marathon events, suggesting that temperature variability over several days preceding and including race day may be associated with SCA occurrence. Runners should remain highly vigilant and take proactive measures under cold/high-risk weather conditions. The on-site presence of trained first responders to initiate CPR is mandatory at these events. A well-planned model of in-event emergency medical services is of vital importance in scenarios such as marathon events.