National early warning score (NEWS) and the new alternative SpO2 scale during rapid response team reviews: a prospective observational study

Background The national early warning score (NEWS) enables early detection of in-hospital patient deterioration and timely activation of hospital’s rapid response team (RRT). NEWS was updated in 2017 to include a separate SpO2 scale for those patients with type II respiratory failure (T2RF). In this study we investigated whether NEWS with and without the new SpO2 scale for the T2RF patients is associated with immediate and in-hospital patient outcomes among the patients actually attended by the RRT. Methods We conducted a two-year prospective observational study including all adult RRT patients without limitations of medical treatment (LOMT) in a large Finnish university associated tertiary level hospital. According to the first vital signs measured by the RRT, we calculated NEWSs for the RRT patients and further utilized the new SpO2 scale for the patients with confirmed T2RF. We used multivariate logistic regression and area under the receiver operating characteristic analyses to test NEWS’s accuracy to predict two distinct outcomes: RRT patient’s I) immediate need for intensive care and/or new LOMT and 2) in-hospital death or discharge with cerebral performance category >2 and/or LOMT. Results The final cohort consisted of 886 RRT patients attended for the first time during their hospitalization. Most common reasons for RRT activation were respiratory (343, 39%) and circulatory (226, 26%) problems. Cohort’s median (Q1, Q3) NEWS at RRT arrival was 8 (5, 10) and remained unchanged if the new SpO2 scale was applied for the 104 patients with confirmed T2RF. Higher NEWS was independently associated with both immediate (OR 1.28; 95% CI 1.22–1.35) and in-hospital (1.15; 1.10–1.21) adverse outcomes. Further, NEWS had fair discrimination for both the immediate (AUROC 0.73; 0.69–0.77) and in-hospital (0.68; 0.64–0.72) outcomes. Utilizing the new SpO2 scale for the patients with confirmed T2RF did not improve the discrimination capability (0.73; 0.69–0.76 and 0.68; 0.64–0.71) for these outcomes, respectively. Conclusions We found that in patients attended by a RRT, the NEWS predicts patient’s hospital outcome with moderate accuracy. We did not find any improvement using the new SpO2 scale in T2RF patients.