Laboratory-derived early warning score for the prediction of in-hospital mortality, intensive care unit admission, medical emergency team activation and cardiac arrest in general medical wards

Background General medical wards admit a varied cohort of patients from the emergency department, some of whom deteriorate during their hospital stay. Currently, we use vital signs based warning scores to predict patients at risk of imminent deterioration, but there is now a growing body of literature that commonly available laboratory results may also help to identify those at risk. Aim To assess whether a laboratory-based admission score can predict in hospital mortality, intensive care unit (ICU) admission, medical emergency team (MET) activation or cardiac arrest in a cohort of Australian general medical patients admitted through the emergency department (ED). Methods We performed a retrospective observational study of all general medical admissions to hospital through the ED in 2015. Admission pathology was used to calculate a risk score. In-patient outcomes of death, ICU transfer, MET call activation or cardiac arrest were collected from hospital records. Results We studied 2942 admissions derived from 2521 patients, with a median age of 81 years. There were 143 in-patient deaths, 82 ICU admissions, 277 MET calls and 14 cardiac arrest calls. The laboratory-based admission score had an area under the receiver operating characteristic curve (AUC-ROC) of 0.76 (95% confidence interval (CI): 0.72-0.80) for inpatient death, an AUC-ROC of 0.79 (95% CI: 0.66-0.93) for inpatient cardiac arrest, an AUC-ROC of 0.64 (95% CI: 0.58-0.70) for ICU transfer and an AUC-ROC of 0.59 (95% CI: 0.55-0.62) for MET call activation. When patients aged over 75 were analysed separately, the AUC-ROC for prediction of in-patient death was 0.74 (95% CI: 0.70-0.78) and increased to 0.86 (95% CI: 0.73-0.98) for the prediction of in-patient cardiac arrest. Conclusion A simple laboratory-derived score obtained at patient admission is a fair to good predictor of subsequent in-patient death or cardiac arrest in general medical patients and in the older patient cohort. Prospective interventional studies are required to ascertain the clinical utility of this admission score.