External Validation of the Simple NULL-PLEASE Clinical Score in Predicting Outcome of Out-of-Hospital Cardiac Arrest

Abstract

Background: Rapid clinical decision-making on further management of patients with out-of-hospital cardiac arrest may be challenging. Recently, a "futility" score (NULL-PLEASE) incorporating multiple adverse resuscitation features (Nonshockable rhythm, Unwitnessed arrest, Long no-flow or Long low-flow period, blood PH <7.2, Lactate >7.0 mmol/L, End-stage chronic kidney disease on dialysis, Age ≥85 years, Still resuscitation, and Extracardiac cause) has been proposed to help identify patients with out-of-hospital cardiac arrest unlikely to survive; however, external independent score validation is lacking.

Methods: We retrospectively validated the NULL-PLEASE predictive ability for early in-hospital outcome of out-of-hospital cardiac arrest in a single-center cohort of 547 consecutive patients with out-of-hospital cardiac arrest who were admitted from April 2013 to October 2016 (mean age, 66.3 ± 13.2 years); 227 patients (41.5%) died. Because pH and lactate were inconsistently measured, a modified NULL-PLEASE score excluding both variables was calculated as the principal analysis. A sensitivity analysis included the subgroup with pH data available (n = 177).

Results: Long low-flow period and age ≥85 years were independently associated with fatal outcome (both P < .001). Patients with a modified NULL-PLEASE score of ≥5 had a 3.3-fold greater risk of fatal outcome compared with a score of 0 to 4 (odds ratio, 3.34; 95% confidence interval [CI], 2.29-4.89; P < .001); 77% of nonsurvivors had a score ≥5; NULL-PLEASE showed a modest predictive ability for fatal outcome (c-statistic 0.658; 95% CI, 0.613-0.704; P < .001). Sensitivity analysis yielded similar results, with 88% of nonsurvivors having a score ≥5.

Conclusions: The NULL-PLEASE score was predictive for early in-hospital outcome of out-of-hospital cardiac arrest, with a 3.3-fold greater odds for fatal outcome at the score values of ≥5.

Keywords: In-hospital mortality; NULL-PLEASE score; Out-of-hospital cardiac arrest; Outcome; Prediction; Resuscitation.