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

Abstract

Study objective

Asystole is the most common initial rhythm in out-of-hospital cardiac arrest (OHCA) but indicates a low likelihood of neurologic recovery. This study aimed to develop a novel scoring system to be easily applied at the time of emergency department arrival for identifying favorable neurologic outcomes in OHCA survivors with an asystole rhythm.

Methods

This study is a secondary analysis based on a previously collected nationwide database, targeting nontraumatic 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 neurologic 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.

Results

Among 19,803 OHCA patients with survival to hospital admission, 6,322 had asystole, and 285 (4.5%) achieved good neurologic outcomes. Factors associated with favorable outcomes included age, witness arrest, bystander cardiopulmonary resuscitation, time from call to hospital arrival, and out-of-hospital 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 to 0.83) and 0.79 (95% CI 0.74 to 0.83) in the derivation and validation cohorts, respectively. After categorizing patients into 3 groups based on probability for good neurologic outcomes, the sensitivity and specificity were as follows: 0.98 (95% CI 0.97 to 0.99) and 0.09 (95% CI 0.09 to 0.10) for the very low predicted probability group (WBC-ASystole ≤2), 0.85 (95% CI 0.82 to 0.89) and 0.54 (95% CI 0.53 to 0.55) for the low predicted probability group (WBC-ASystole 3 to 4), and 0.36 (95% CI 0.34 to 0.39) and 0.93 (95% CI 0.92 to 0.93) for fair predicted probability group (WBC-ASystole≥5), respectively.

Conclusions

Although external validation studies must be performed, among OHCA patients with asystole, the WBC-ASystole scoring system may identify those patients who are likely to have a favorable neurologic outcome.