A Simple Scoring System for Identifying Favorable Neurologic Outcomes Among Out-of-Hospital Cardiac Arrest Patients With Asystole

Abstract

Study objectiveAsystole is the most common initial rhythm in out-of-hospital cardiac arrest (OHCA), but indicates a low likelihood of neurological recovery. This study aimed to develop a novel scoring system to be easily applied at the time of emergency department arrival for identifying favorable neurological outcomes in OHCA survivors with an asystole rhythm. MethodsThis study is a secondary analysis based on a previously collected nationwide database, targeting non-traumatic adult OHCA patients aged ≥ 18 years with an asystole rhythm who achieved Return of Spontaneous Circulation (ROSC) between January 2016 and December 2020. The primary outcome was a favorable neurological outcome defined as Cerebral Performance Categories scores of 1 or 2 at hospital discharge. A prediction model was developed through multivariable logistic regression analysis in a derivation cohort in the form of a scoring system (WBC-ASystole). The performance and calibration of the model were tested using an internal validation cohort. ResultsAmong 19,803 OHCA patients with survival to hospital admission, 6,322 had asystole, and 285 (4.5%) achieved good neurological outcomes. Factors associated with favorable outcomes included age, witness arrest, bystander cardiopulmonary resuscitation, time from call to hospital arrival, and prehospital ROSC achievement. The WBC-ASystole score, totaling 11 points, exhibited a predictive performance with an area under the receiver operating characteristic curve of 0.80 (95% confidence interval [CI]: 0.76–0.83) and 0.79 (95% CI: 0.74–0.83) in the derivation and validation cohorts, respectively. After categorizing patients into three groups based on probability for good neurological outcomes, the sensitivity and specificity were as follows: 0.98 (95% CI: 0.97–0.99) and 0.09 (95% CI: 0.09–0.10) for the very low (WBC-ASystole: ≤2), 0.85 (95% CI: 0.82–0.89) and 0.54 (95% CI: 0.53–0.55) for the low (WBC-ASystole: 3–4), and 0.36 (95% CI: 0.34–0.39) and 0.93 (95% CI: 0.92–0.93) for fair predicted probability group (WBC-ASystole: ≥5). ConclusionsAlthough external validation studies must be performed, among OHCA with asystole, the WBC-ASystole scoring system may identify those patients who are likely to have a favorable neurological outcome.