Comparison of P-POSSUM and O-POSSUM in predicting mortality after oesophagogastric resections. Issue 979 (8th May 2007)

• Record Type: Journal Article
• Authors: Nagabhushan, J S; Srinath, S; Weir, F; Angerson, W J; Sugden, B A; Morran, C G
• Is Part Of: Postgraduate medical journal. Volume 83:Issue 979(2007)
• Page Start: 355
• Page End: 358
• Publication Date: 2007-05-08
• Subjects: AUC, area under the receiver–operator characteristic curve -- H–L, Hosmer–Lemeshow -- POSSUM, Physiological and Operative Severity Score for the enumeration of Mortality and morbidity -- ROC, receiver–operator characteristic -- SMR, standardised mortality ratio; Medicine -- Periodicals; 610
• DOI: 10.1136/pgmj.2006.053223
• Languages: English
• ISSNs: 0032-5473

Abstract

Abstract : Background: P-POSSUM (Physiological and Operative Severity Score for the enumeration of Mortality and morbidity) predicts mortality and morbidity in general surgical patients providing an adjunct to surgical audit. O-POSSUM was designed specifically to predict mortality and morbidity in patients undergoing oesophagogastric surgery. Aim: To compare P-POSSUM and O-POSSUM in predicting surgical mortality in patients undergoing elective oesophagogastric cancer resections. Methods: Elective oesophagogastric cancer resections in a district general hospital from 1990 to 2002 were scored by P-POSSUM and O-POSSUM methods. Observed mortality rates were compared to predicted mortality rates in six risk groups for each model using the Hosmer–Lemeshow goodness-of-fit test. The power to discriminate between patients who died and those who survived was assessed using the area under the receiver–operator characteristic (ROC) curve. Results: 313 patients underwent oesophagogastric resections. 32 died within 30 days (10.2%). P-POSSUM predicted 36 deaths (χ 2 = 15.19, df = 6, p = 0.019, Hosmer–Lemeshow goodness-of-fit test), giving a standardised mortality ratio (SMR) of 0.89. O-POSSUM predicted 49 deaths (χ 2 = 16.51, df = 6, p = 0.011), giving an SMR of 0.65. The area under the ROC curve was 0.68 (95% confidence interval 0.59 to 0.76) for P-POSSUM and 0.61 (95% confidence interval 0.50 to 0.72) for O-POSSUM. Conclusion: Neither model accurately predicted the risk of postoperative death. P-POSSUM provided a better fit to observed results than O-POSSUM, which overpredicted total mortality. P-POSSUM also had superior discriminatory power.