How comorbidities impact Early Warning Score as a predictor of 7-day mortality.

Background: Early Warning Score systems are used to monitor patients at risk of deterioration. How comorbidities impact Early Warning Score's ability to predict short-term mortality in the emergency department is not fully elucidated. The aim of the study was to investigate how comorbidities impact Early Warning Score as predictor of 7-day mortality. Methods: This is an observational cohort study of adult emergency department patients attending one of the five emergency departments in Central Region Denmark from 1 March 2015 to 31 May 2015. Charlson Comorbidity Index was used as a measure of comorbidities. Logistic regression was used to calculate the odds ratio for 7-day mortality. Patients were compared in three groups: Charlson Comorbidity Index: 0, 1-2, 3+. Results: A total of 30 060 adult patients attended one of the five emergency departments. Nineteen thousand one hundred twenty-three patients were included. Charlson Comorbidity Index 3+ patients presenting with Early Warning Score 0, 1-2 or 3-4 had significantly higher odds ratio of 7-day mortality compared to Charlson Comorbidity Index 0 patients with equal Early Warning Score. For patients with Early Warning Score 5+, Charlson Comorbidity Index -status had no significant impact on 7-day mortality after adjusting for age. Conclusion: In patients presenting with lower acuity (Early Warning Score 0-4) Charlson Comorbidity Index has a significant impact on 7-day mortality regardless of Early Warning Score. Including Charlson Comorbidity Index status in Early Warning Score or adjusting for Charlson Comorbidity Index -status could increase the predictive value of Early Warning Score in predicting 7-day mortality.