External validation of the simple NULL-PLEASE clinical score in predicting outcomes of out-of-hospital cardiac arrest in the Danish population – A nationwide registry-based study

Abstract

AimThe NULL-PLEASE score (Nonshockable rhythm, Unwitnessed arrest, Long no-flow or Long low-flow period, blood pH < 7.2, Lactate > 7.0 mmol/L, End-stage renal disease on dialysis, Age ≥85 years, Still resuscitation, and Extracardiac cause) may identify patients with out-of-hospital cardiac arrest (OHCA) unlikely to survive. We aimed to validate the NULL-PLEASE score in a nationwide setting. MethodsWe used Danish nationwide registry data from 2001 to 2019 and identified OHCA survivors with return of spontaneous circulation (ROSC) or ongoing cardiopulmonary resuscitation at hospital arrival. The primary outcome was 1-day mortality. Secondary outcomes were 30-day mortality and the combined outcome of 1-year mortality or anoxic brain damage. The risks of outcomes were estimated using logistic regression with a NULL-PLEASE score of 0 as reference (range 0–14). The predictive ability of the score was examined using the area under the receiver operating characteristics (AUCROC) curve. ResultsA total of 3,881 patients were included in the analyses. One-day mortality was 35%, 30-day mortality was 61%, and 68% experienced the combined outcome. For a NULL-PLEASE score ≥9 (n = 244) the absolute risks were: 1-day mortality: 80.7% (95% confidence interval [CI]: 75.8–85.7%); 30-day mortality: 98.0% (95% CI: 96.2–99.7%); and the combined outcome: 98.4% (95% CI: 96.8–100.0%). Corresponding AUCROC values were 0.800 (95% CI: 0.786–0.814) for 1-day mortality, 0.827 (95% CI: 0.814–0.840) for 30-day mortality, and 0.828 (95% CI: 0.815–0.841) for the combined outcome. ConclusionsIn a nationwide OHCA-cohort, AUCROC values for the predictive ability of NULL-PLEASE were high for all outcomes. However, some survived even with high NULL-PLEASE scores.