Usefulness of the NULL-PLEASE Score to predict 1 survival in out-of hospital cardiac arrest

Purpose: Out-of-hospital cardiac arrest (OHCA) carries a very high mortality even after successful cardiopulmonary resuscitation. Currently, information given to relatives regarding prognosis following resuscitation is often emotive and subjective, and varies with clinician experience. We aimed to validate the NULL-PLEASE score to predict survival following OHCA. Methods: A multicentre cohort study was conducted, with retrospective and prospective validation in consecutive unselected patients presenting with OHCA. The NULL-PLEASE score was calculated by attributing points to the following variables: Non-shockable initial rhythm, Unwitnessed arrest, Long low-flow period, Long no-flow period, pH<7.2, Lactate>7.0 mmol/l, End-stage renal failure, Age ≥85 years, Still resuscitation and Extra cardiac cause. The primary outcome was in-hospital death. Results: We assessed 700 patients admitted with OHCA, of whom 47% survived to discharge. In 300 patients we performed a retrospective validation, followed by prospective validation in 400 patients. The NULL-PLEASE score was lower in patients who survived compared to those who died (0 [IQR 0-1] vs. 4 [IQR 2-4], p<0.0005) and strongly predictive of in-hospital death (c-statistic 0.874, 95% confidence interval [CI] 0.848-0.899). Patients with a score ≥3 had a 24-fold increased risk of death (OR 23.6; 95%CI 14.840-37.5, p<0.0005) compared to those with lower scores. A score ≥3 has a 91% positive predictive value for in-hospital death, whilst a score <3 predicts a 71% chance of survival. Conclusion: The easy-to-use NULL-PLEASE score predicts in-hospital mortality with high specificity and can help clinicians explain the prognosis to relatives in an easy-to-understand, objective fashion, to realistically prepare them for the future.