Objectives To examine whether the predictive value of the early warning score (EWS) could be improved by including rapid lactate levels, and to compare the modified EWS with the pre-existing risk scoring systems.

Design Retrospective observational study in South Korea.

Setting An urban, academic, tertiary hospital.

Participants Consecutive adult patients who were admitted to the medical intensive care unit via the emergency department (ED).

Outcome measures A newly developed EWS—the VitalPAC EWS (ViEWS), was used in the present study. Lactate level, ViEWS and HOTEL score were obtained from patients at presentation to the ED, and APACHE II, SAPS II and SAPS III scores were obtained after admission. The area under curve of each risk scoring system for in-hospital, 1-week, 2-week and 4-week mortality was compared.

Results 151 patients were enrolled and the mortality was 42.4%. The ViEWS-L score was calculated as follows: ViEWS-L score=ViEWS+lactate (mmol/l) according to the regression coefficient. The mean ViEWS-L score was 11.6±7.3. The ViEWS-L score had a better predictive value than the ViEWS score for hospital mortality (0.802 vs 0.742, p=0.009), 1-week mortality (0.842 vs 0.707, p<0.001), 2-week mortality (0.827 vs 0.729, p<0.001) and 4-week mortality (0.803 vs 0.732, p=0.003). The ViEWS-L score also had a better predictive value than the HOTEL and APACHE II scores. The predictive value of ViEWS-L was comparable with SAPS II and SAPS III.

Conclusions The ViEWS-L score performed as well as or better than the pre-existing risk scoring systems in predicting mortality in critically ill medical patients who were admitted to the medical intensive care unit via the ED.