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This is the Scientific Surgery Archive, which contains all randomized clinical trials in surgery that have been identified by searching the top 50 English language medical journal issues since January 1998. Compiled by Jonothan J. Earnshaw, former Editor-in-Chief, BJS

A carotid POSSUM model for predicting death. BJS 2001; 88: 600-601.

Published: 6th December 2002

Authors: G. Kuhan, D. Prytherch, G. L. Sutton, S. P. Payne, I. Chetter, A. Abidia et al.

Background

Risk adjustment to allow for differences in case mix aids comparative audit of carotid endarterectomy (CEA). The aim of this study was to test the predictive accuracy of P‐POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity – Portsmouth predictor equation for mortality) and V‐POSSUM (P‐POSSUM‐based model for vascular surgery) and to develop a procedure‐specific model for CEA.

Method

A total of 709 CEAs performed in two vascular units from 1992 to 2000 were analysed. The physiological and the operative severity scores were calculated; the outcome used was 30‐day mortality. Predicted mortality was calculated using P‐POSSUM, V‐POSSUM and V‐POSSUM (physiology only = PS) equations. The observed and the predicted mortality were compared. The new model was developed on a set of 350 CEAs and validated on 359 CEAs. The data sets of the two units were combined and split into two by the procedure date order. The predictive accuracy of the model was analysed with the χ2 test.

Results












Observed deaths
Predicted deaths
χ2
P




P‐POSSUM
11
31
15·8
0·003


V‐POSSUM
11
37
22·9
<0·001


V‐POSSUM (PS)
11
48
33·9
<0·001




Conclusion

P‐POSSUM and V‐POSSUM overpredict mortality and are unsuitable for the comparative audit of CEA. Procedure‐specific models based on P‐POSSUM can accurately predict death. © 2001 British Journal of Surgery Society Ltd

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