The variable relationship between the National Early Warning Score on admission to hospital, the primary discharge diagnosis, and in-hospital mortality.

Background: Patients with an elevated admission National Early Warning Score (NEWS) are more likely to die while in hospital. However, it is not known if this increased mortality risk is the same for all diagnoses. The aim of this study was to determine and compare the increased risk of in-hospital mortality associated with an elevated NEWS and different primary discharge diagnoses in unselected emergency admissions to a UK university teaching hospital.

Methods: A non-interventional observational study of 122,321 consecutive, unselected, adult patients with complete data admitted as an emergency between 2014 and 2022.

Results: The overall in-hospital mortality was 4.3%. Eighty diagnostic groupings accounted for 85.8% of all admissions and 89.4% of all in-hospital deaths. Depending on diagnostic grouping, the risk of mortality associated with an admission NEWS ≥ 3 ranged from 2.3- to 100-fold. For example, the in-hospital mortality of COPD patients increased from 1.9% for those with admission NEWS < 3 to 35.6% for those with NEWS ≥ 3, for chest pain mortality increased from 0.1 to 3.9%, and for patients with an opiate overdose from 0.2 to 7.7%. Conversely, for admission NEWS < 3, aspiration pneumonia and intracranial hemorrhage had in-hospital mortalities of 13.7% and 12.1%, respectively.

Discussion: There is enormous variation in the mortality risk associated with an increased admission NEWS in different commonly encountered diagnoses. Therefore, the mortality risk of some 'low risk' conditions can be dramatically increased if their admission NEWS is elevated, whereas some 'high risk' conditions are still likely to die even if their admission NEWS is low.