Adjusting EWS scores for altitude above sea level: is it necessary to predict sepsis mortality in the emergency room?

Abstract

Background: Sepsis mortality can be significantly reduced with early diagnosis and appropriate treatment. It is crucial to have tools that enable the early identification of patients at high risk of sepsis mortality from the triage stage. The National Early Warning Score (NEWS) and recently the International Early Warning Score (IEWS), are widely used for this purpose. However, its oxygenation parameters are primarily validated in populations at sea level. Given that patient oxygenation varies with altitude, there is a need to investigate the applicability of this scores at different altitudes. The purpose of this study is to compare the discriminatory capacity of sepsis mortality in emergency departments between the standard NEWS and IEWS scale and a NEWS and IEWS scale adjusted for barometric pressure in Bogotá, a city located 2600 m above sea level. A prospective recruitment was conducted in the triage area of the emergency department, including all patients with suspected sepsis. The scales under evaluation were calculated. Subsequently, the sensitivity, specificity, predictive values, and areas under the curve (AUC) of each scale were assessed for mortality prediction.

Results: A total of 304 patients were recruited. The overall mortality rate was 19.4% and the septic shock mortality rate was 59.3%. The AUC for the standard NEWS was 0.78 (95% CI: 0.72-0.83), and for the standard IEWS was 0.81(95% CI: 0.75-0.87), altitude-adjusted NEWS, it was 0.79(95% CI: 0.73-0.84), and for the altitude-adjusted IEWS was 0.82(95% CI: 0.76-0.88).

Conclusions: Adjustment of oxygen saturation for altitude above sea level in NEWS (NEWSa) does not improve its predictive capacity for mortality in patients with sepsis in the emergency department, however, this same adjustment in the IEWS value significantly improves the predictive capacity compared to NEWS and NEWSa.