Kim KH, Ro YS, Park JH, et al. - Researchers intended to determine if there is an association between the case volume of ambulance stations and clinical outcomes in out-of-hospital cardiac arrests (OHCAs) by the number of emergency medical services (EMS) providers at the scene. Between 2015 and 2018, adult cardiac EMS-treated OHCAs were enrolled. The primary exposure was the annual OHCA case volumes of 204 Korean ambulance stations, which were divided into three categories: low-volume (< 100), moderate-volume (100–159), and high-volume (≥ 160). In total, 92,534 patients were enrolled. Findings suggested an association of OHCA case volumes of ambulance stations with clinical outcomes after cardiac arrest.