POSSUM for Operative Morbidity and Mortality Risk
Physiological Score
Operative Severity Score
Why Use
The POSSUM calculates risk for operative morbidity and mortality, which can be used to help patients and family members make informed decisions about surgery. Similar / alternative tools: There are procedure-specific models for colorectal surgery (CR-POSSUM), vascular surgery (Vascular-POSSUM), and esophagogastric surgery (O-POSSUM, O for oesophagogastric). APACHE II is a similar assessment tool but is applied to intensive care patients and only assesses the risk of mortality. The Surgical Apgar Score (SAS) offers similar estimates for morbidity and mortality. The POSSUM is more comprehensive than the SAS (which is calculated based on 3 parameters), but the SAS is more objective. The SAS uses intraoperative parameters exclusively, whereas the POSSUM uses preoperative parameters. The ACS NSQIP risk calculator is a newer, similar assessment. It has not yet been as rigorously validated as the POSSUM. Other disease-specific scores may be used to assess risk, e.g. Revised Cardiac Risk Index for Pre-Operative Risk .
When to Use
Patients undergoing emergency and elective general surgical procedures.
Formula
Pearls / Pitfalls
The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) assesses morbidity and mortality for general surgery. It can be used for both emergency and elective surgery. The original POSSUM was modified by researchers in Portsmouth who derived a more accurate prediction of mortality, and the P-POSSUM model is now more commonly used to calculate the mortality component. The POSSUM data set excludes trauma patients, so POSSUM should NOT be used to predict morbidity and mortality after trauma surgery. The POSSUM should NOT dictate the decision to operate, which is a clinical decision. Physiological score should be calculated at the time of surgery, not at the time of admission. The definitions of surgical procedures are guidelines only. Not all procedures are listed, and the closest approximation should be selected. The POSSUM may overestimate risk in hepatopancreaticobiliary surgery.
Management
The POSSUM should be calculated when the decision to operate is made. The percentages can be shared with the patient when discussing the risks of the operation.
Advice
Risk estimates can help patients and family members in the process of informed consent and in management of expectations.
More Information
Severity of surgeries: Moderate: appendectomy, cholecystectomy, mastectomy, TURP. Major: laparotomy, bowel resection, cholecystectomy w choledochotomy, peripheral vascular procedure or major amputation. Major+: aortic procedure, abdominoperineal resection, pancreatic or liver resection, esophagogastrectomy. Morbidity was defined as any of the following: Hemorrhage. Infection (including pneumonia, wound infection, UTI, deep infection, septicemia, and fever of unknown origin). Wound dehiscence or anastomotic leak. Thrombosis (including) DVT, PE, CVA, or MI. Cardiac failure. Impaired renal function (urea increase >5 mmol/L from pre-op). Hypotension (respiratory failure). “Any other complication”.