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An evaluation of POSSUM and P-POSSUM scoring in predicting post-operative mortality in a level 1 critical care setting

Scott, Sarah; Lund, Jonathan N.; Gold, Stuart; Elliott, Richard; Vater, Mair; Chakrabarty, Mallicka P.; Heinink, Thomas P.; Williams, John P.

An evaluation of POSSUM and P-POSSUM scoring in predicting post-operative mortality in a level 1 critical care setting Thumbnail


Sarah Scott

Clinical Associate Professor

Stuart Gold

Richard Elliott

Mair Vater

Mallicka P. Chakrabarty

Thomas P. Heinink

Clinical Associate Professor



POSSUM and P-POSSUM are used in the assessment of outcomes in surgical patients. Neither scoring systems’ accuracy has been established where a level 1 critical care facility (level 1 care ward) is available for perioperative care. We compared POSSUM and P-POSSUM predicted with observed mortality on a level 1 care ward.

A prospective, observational study was performed between May 2000 and June 2008. POSSUM and P-POSSUM scores were calculated for all postoperative patients who were admitted to the level 1 care ward. Data for post-operative mortality were obtained from hospital records for 2552 episodes of patient care. Observed vs expected mortality was compared using receiver operating characteristic (ROC) curves and the goodness of fit assessed using the Hosmer-Lemeshow equation.

ROC curves show good discriminative ability between survivors and non-survivors for POSSUM and P-POSSUM. Physiological score had far higher discrimination than operative score. Both models showed poor calibration and poor goodness of fit (Hosmer-Lemeshow). Observed to expected (O:E) mortality ratio for POSSUM and P-POSSUM indicated significantly fewer than expected deaths in all deciles of risk.

Our data suggest a 30-60% reduction in O:E mortality. We suggest that the use of POSSUM models to predict mortality in patients admitted to level 1 care ward is inappropriate or that a recalibration of POSSUM is required to make it useful in a level 1 care ward setting.

Journal Article Type Article
Acceptance Date Oct 28, 2014
Online Publication Date Nov 18, 2014
Publication Date Nov 18, 2014
Deposit Date Aug 1, 2017
Publicly Available Date Aug 1, 2017
Journal BMC Anesthesiology
Electronic ISSN 1471-2253
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 14
Issue 1
Article Number 104
Public URL
Publisher URL


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