External validation of the simple NULL-PLEASE clinical score in predicting outcomes in men and women with out-of-hospital cardiac arrest - a nationwide registry-based study.

Aim: The 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) was developed to predict survival in out-of-hospital cardiac arrest (OHCA) patients. Because survival differs between sexes, we aimed to validate NULL-PLEASE separately in men and women.

Methods: Men and women with return of spontaneous circulation (ROSC) or ongoing cardiopulmonary resuscitation at hospital arrival from 2001-2019 were identified using Danish nationwide registries. The primary outcome was 1-day mortality. Secondary outcomes were defined as 30-day mortality and the combination of 1-year mortality or anoxic brain damage. Logistic regression was used for outcome risk estimation (reference: NULL-PLEASE=0). Interaction analyses was performed between the NULL-PLEASE score and sex. The predictive ability was assessed using area under the receiver operating characteristics (AUCROC) curves.

Results: We included 2,599 men and 1,280 women. One-day mortality for men and women was 36% and 50%; 30-day mortality was 56% and 71%; and 63% and 78% experienced the combined 1-year outcome. AUCROC values for 1-day mortality were for men: 0.828 (95% CI: 0.813-0.844); and for women: 0.754 (95% CI: 0.728-0.780). Results were similar for secondary outcomes. We found significant interaction between the NULL-PLEASE score and sex: 1-day mortality: P<0.001, 30-day mortality: P=0.04, combined outcome: P=0.09.

Conclusions: In a nationwide OHCA-cohort, the predictive ability of the NULL-PLEASE score was higher in men than in women.