The ABC (Age, Bystander, and Cardiogram) score for predicting neurological outcomes of cardiac arrests without pre-hospital return of spontaneous circulation: A nationwide population-based study.

Aim: We previously proposed the ABC score to predict the neurological outcomes of cardiac arrest without prehospital return of spontaneous circulation (ROSC). Using nationwide population-based data, this study aimed to validate the ABC score through various resuscitation guideline periods. Methods: We analysed cases with cardiac arrest due to internal causes and failure to achieve prehospital ROSC in the All-Japan Utstein Registry. Patients from the 2007-2009, 2012-2014, and 2017-2019 periods were classified into the 2005, 2010, and 2015 guideline groups, respectively. Neurological outcomes were assessed using cerebral performance categories (CPCs) one month after the cardiac arrest. We defined CPC 1-2 as a favourable outcome. We evaluated the test characteristics of the ABC score, which could range from 0 to 3. Results: Among the 162,710, 186,228, and 190,794 patients in the 2005, 2010, and 2015 guideline groups, 0.7%, 0.8%, and 0.9% of the patients had CPC 1-2, respectively. The proportions of CPC 1-2 were 2.9%, 3.6%, and 4.6% in patients with ABC scores of 2 and were 9.5%, 13.3%, and 16.8% in patients with ABC scores of 3, respectively. Among patients with ABC scores of 0, 0.2%, 0.1%, and 0.2%, all had CPC 1-2, respectively. The areas under the receiver operating characteristic curves for the ABC score were 0.798, 0.822, and 0.828, respectively. Conclusions: The ABC score had acceptable discrimination for neurological outcomes in patients without prehospital ROSC in the three guideline periods.