Logistic early warning scores to predict death, cardiac arrest or unplanned intensive care unit re‐admission after cardiac surgery

Abstract

Summary NHS England recently mandated that the National Early Warning Score of vital signs be used in all acute hospital trusts in the UK despite limited validation in the postoperative setting. We undertook a multicentre UK study of 13,631 patients discharged from intensive care after risk‐stratified cardiac surgery in four centres, all of which used VitalPACTM to electronically collect postoperative National Early Warning Score vital signs. We analysed 540,127 sets of vital signs to generate a logistic score, the discrimination of which we compared with the national additive score for the composite outcome of: in‐hospital death; cardiac arrest; or unplanned intensive care admission. There were 578 patients (4.2%) with an outcome that followed 4300 sets of observations (0.8%) in the preceding 24 h: 499 out of 578 (86%) patients had unplanned re‐admissions to intensive care. Discrimination by the logistic score was significantly better than the additive score. Respective areas (95%CI) under the receiver‐operating characteristic curve with 24‐h and 6‐h vital signs were: 0.779 (0.771–0.786) vs. 0.754 (0.746–0.761), p < 0.001; and 0.841 (0.829–0.853) vs. 0.813 (0.800–0.825), p < 0.001, respectively. Our proposed logistic Early Warning Score was better than the current National Early Warning Score at discriminating patients who had an event after cardiac surgery from those who did not.

Improving early warning scores – more data, better validation, the same response: a reply

“… for their comments on our editorial , which accompanied the article by Chiu et al. and agree with the definition of external validation that they provide. In broad terms, internal validation is concerned with reproducibility of a prediction model, whereas external validation is concerned with the transportability of model predictions to other settings and populations.…”

Improving early warning scores – more data, better validation, the same response

“…The study by Chiu et al. in this issue of Anaesthesia may represent the next step towards future EWS, namely population‐specific predictions developed using statistical analyses of large populations derived from electronic health records (EHR) . Cardiac surgery in the UK has many good risk prediction tools, but these all aim to predict mortality pre‐operatively (EuroSCORE‐2 ) or in the first 24 h of ICU admission (ICNARC ARCtIC ).…”

Improving early warning scores – more data, better validation, the same response

“…Multiple predictive performance and validation techniques were utilised and these are summarised in the supporting information which accompanies the online version of our paper (Appendix 3: Table A3.4.) .…”