The AWA prehospital scoring system predicts 30-day mortality after out-of-hospital cardiac arrest with high accuracy: an SOS-KANTO 2017 registry study

Out-of-hospital cardiac arrest (OHCA) has a very high mortality rate. Standard emergency responses to OHCA may lead to unwanted resuscitation, particularly in elderly patients, and futile interventions impose additional strain on already limited healthcare resources. An appropriate prognostic scoring system for OHCA could reduce these adverse effects, but existing systems all rely on information unavailable in the prehospital setting. This study developed and internally validated a simple scoring system based exclusively on prehospital parameters that predicts 30-day mortality in OHCA patients. This retrospective study used the Japanese SOS-KANTO registry. The primary outcome was 30-day mortality. A multivariable logistic regression model using prehospital predictors was converted into a point-based scoring system. Model performance and internal validation were assessed. Among the 9120 patients included in the study, the 30-day mortality rate was 93.8%. The final prediction model included age, unwitnessed arrest, and asystole as initial rhythm. It showed good discriminative ability and good calibration. On a 9-point scoring system, a total score of 9 (patients aged ≥ 90 years, with unwitnessed arrest, and an initial rhythm of asystole) predicted 30-day mortality with a specificity of 99.66% and a positive predictive value of 99.66%. We have developed a practical scoring system based on three prehospital parameters—age, witness status, and asystole (AWA)—that accurately predicts 30-day mortality after OHCA. Our simple and accurate AWA scoring system facilitates rapid assessment in prehospital settings, supporting timely decision-making.