Only normalisation of physiology will reduce risk of mortality after discharge

EDITOR—The triage model described by Daly et al to identify patients at higher risk of death after discharge from intensive care seeks to address a number of important issues.1 Daly et al used five variables (patient's age, chronic health points, length of stay in intensive care, acute physiology score, and cardiothoracic surgery) to produce a predictive model that gave a relative risk of death of 9.44 in the developmental group (mortality 14% in those at risk, 1.5% in those not at risk according to this model) and 6.76 in the validation group (mortality 28% in those at risk on day of discharge, 4% in those not at risk in the 48 hours before discharge). This adds further statistical background to previous studies, which had highlighted four of these variables as risk factors at discharge from intensive care. 2 3 The fifth variable, cardiothoracic surgery (57% of the developmental model), makes this group atypical of most intensive care units in the United Kingdom, although this point is acknowledged in the internet version of the paper.

Daly et al claim that if patients at risk on day of discharge stay an extra 48 hours in intensive care, mortality after discharge may be reduced by 39%. This piece of statistical fast footwork is given, although no prospective component to the study shows that an extra 48 hours in intensive care will reduce the risk of (any or most or all) patients. Of the five factors …