P-POSSUM models for abdominal aortic aneurysm surgery

Abstract

Background and methods: POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) data on 444 (213 emergency, 231 elective) admissions for abdominal aortic aneurysm (AAA) surgery between August 1993 and July 2000 were analysed using the P‐POSSUM equation for general surgery and the P‐POSSUM equations developed for the Vascular Surgical Society of Great Britain and Ireland (physiological and operative and physiology only). Results: All three equations successfully modelled the elective admissions but failed to fit the emergency admissions and the elective and emergency admissions combined. This suggests that admission method (not a POSSUM data item) is an important factor for patients with AAA. However, with these data it was not possible to generate a model, including admission method, that successfully modelled the combined elective and emergency data. Emergency AAAs had to be treated separately. The 213 emergency admissions were divided into two groups by operation date. The first 106 (training set) were used to form logistic regression models following the P‐POSSUM methodology. These models were found successfully to fit the remaining 107 records (test set) on prospective application, as shown in the Table. Risk range Mean risk No. of operations Predicted deaths Reported deaths χ2 > 0, ≤ 3023·5824681·27> 30, ≤ 4537·894517160·10> 45, ≤ 6051·45231282·56> 60, ≤ 10068·99151090·57> 0, ≤ 10041·9510745414·50 Conclusion: Emergency AAAs appear to be fundamentally different from elective AAAs and other vascular cases, and require their own distinct risk model. The ability to model risk for elective AAAs using a physiology‐only risk model could perhaps be used to optimize the timing of operation as well as informing all concerned of the risks involved. © 2001 British Journal of Surgery Society Ltd

Efficacy of Possum in Surgical Audit of Patient Undergoing Emergency Surgery at Nepalgunj Medical College

“…Such result were seen in different studies that had showed no difference in observed 2,6 and expected morbidity with O: E ratio around 1 . But this result is in contrast to numerous studies where expected to 7,8 observed morbidity corresponds to each other .…”