Evaluation of POSSUM in predicting post-operative morbidity in patients undergoing pancreaticoduodenectomy

The accuracy of pre-operative (P)-POSSUM scoring and cardiopulmonary exercise testing in predicting morbidity and mortality after pancreatic and liver surgery: A systematic review

Background

Cardiopulmonary exercise-testing (CPET) and the (Portsmouth) Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity ((P)-POSSUM) are used as pre-operative risk stratification and audit tools in general surgery, however, both have been demonstrated to have limitations in major hepatopancreatobiliary (HPB) surgery.

Materials and methods

The aim of this review is to determine if CPET and (P)-POSSUM scoring systems accurately predict morbidity and mortality. Eligible articles were identified with an electronic database search. Analysis according to surgery type and tool used was performed.

Results

Twenty-five studies were included in the final review. POSSUM predicted morbidity demonstrated weighted O/E ratios of 0.75(95%CI0.57–0.97) in hepatic surgery and 0.85(95%CI0.8–0.9) in pancreatic surgery. P-POSSUM predicted mortality in pancreatic surgery demonstrated an O/E ratio of 0.75(95%CI0.27–2.13) and 0.94(95%CI0.57–1.55) in hepatic surgery. In both pancreatic and hepatic surgery an anaerobic threshold(AT) of between 9 0.5–11.5 ml/kg/min was predictive of post-operative complications, and in pancreatic surgery ventilatory equivalence of carbon dioxide(˙VE/˙VCO2) was predictive of 30-day mortality.

Conclusion

POSSUM demonstrates an overall lack of predictive fit for morbidity, whilst CPET variables provide some predictive power for post-operative outcomes. Development of a new HPB specific risk prediction tool would be beneficial; the combination of parameters from POSSUM and CPET, alongside HPB specific markers could overcome current limitations.

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Current pre-operative scoring for pancreatic and liver surgery is inaccurate.

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In pancreatic and liver surgery anaerobic threshold scores were predictive of complications.

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In pancreatic surgery ventilatory equivalence of carbon dioxide was predictive of mortality.

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P-POSSUM is inaccurate for predicting mortality and morbidity in pancreatic surgery.

Does adding ICU data to the POSSUM score improve the prediction of outcomes following surgery for upper gastrointestinal malignancies?

Surgery for upper gastrointestinal malignancy carries a high postoperative mortality and morbidity risk. The importance of preoperative physiological reserve and intraoperative events in determining clinical outcomes is recognised in the Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) score that comprises variables relevant to both phases. Whether adding variables linked to ICU admission characteristics improves the predictive capacity of POSSUM is unclear, especially in an Australian/New Zealand healthcare context. This study aimed to evaluate the predictive capacity of the POSSUM score for 30-day mortality and in-hospital morbidity in 80 patients undergoing resection of oesophageal (28%), gastric (26%) or pancreatic (46%) malignancies and admitted to ICU. The 30-day mortality was 8.8% and 65% of patients developed some postoperative complication. Receiver operating characteristics generated an area under the curve (95% CI) to predict mortality by Portsmouth POSSUM of 0.87 (0.77 to 0.93) and morbidity by POSSUM of 0.67 (0.55 to 0.77). Multiple regression analysis including biochemical variables and vital signs on admission to ICU identified renal function parameters, fluid balance and need for cardiorespiratory support beyond the first postoperative day as independent factors associated with mortality and morbidity (in addition to the POSSUM score) but the inclusion of these variables in a logistic regression model did not significantly improve the predictive capacity for mortality (to area under the curve 0.93 [0.85 to 0.97]) or morbidity (to area under the curve 0.67 [0.55 to 0.78]). In conclusion, the POSSUM score provides clinically useful predictive capacity in patients undergoing surgery for upper gastrointestinal malignancies. The incorporation of ICU admission variables to the pre- and intraoperative POSSUM variables did not significantly enhance the precision.

Assessing surgical quality: comparison of general and procedure-specific morbidity estimation models for the risk adjustment of pancreaticoduodenectomy outcomes

INTRODUCTION

The use of outcomes to evaluate surgical quality implies the need for detailed risk adjustment. The physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM) is a generally applicable risk adjustment model suitable for pancreatic surgery. A pancreaticoduodenectomy (PD)-specific intraoperative pancreatic risk assessment (IPRA) estimates the risk of postoperative pancreatic fistula (POPF) and associated morbidity based on factors that are not incorporated into POSSUM.

OBJECTIVE

The aim of the study was to compare the risk estimations of POSSUM and IPRA in patients undergoing PD.

METHODS

An observational single-center cohort study was conducted including 195 patients undergoing PD in 2008-2010. POSSUM and IPRA data were recorded prospectively. Incidence and severity of postoperative morbidity was recorded according to established definitions. The cohort was grouped by POSSUM and IPRA risk groups. The estimated and observed outcomes and morbidity profiles of POSSUM and IPRA were scrutinized.

RESULTS

POSSUM-estimated risk (62 %) corresponded with observed total morbidity (65 %). Severe morbidity was 17 % and in-hospital-mortality 3.1 %. Individual and grouped POSSUM risk estimates did not reveal associations with incidence (p = 0.637) or severity (p = 0.321) of total morbidity or POPF. The IPRA model identified patients with high POPF risk (p < 0.001), but was even associated with incidence (p < 0.001) and severity (p < 0.001) of total morbidity.

CONCLUSION

The risk factors defined by a PD-specific model were significantly stronger predictive indicators for the incidence and severity of postoperative morbidity than the factors incorporated in POSSUM. If available, reliable procedure-specific risk factors should be utilized in the risk adjustment of surgical outcomes. For pancreatic surgery, generally applicable tools such as POSSUM still have to prove their relevance.

Value of general surgical risk models for predicting postoperative morbidity and mortality in pancreatic resections for pancreatobiliary carcinomas

BACKGROUND

The present study evaluated the utility of general surgical risk models to predict postoperative morbidity and mortality in the specialty field of pancreatic resections for pancreatobiliary carcinomas.

METHODS

We investigated Estimation of Physiologic Ability and Surgical Stress (E-PASS), its modified version (mE-PASS), and Portsmouth Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM) in 231 patients undergoing pancreatoduodenectomy or distal pancreatectomy (Group A). We also analyzed E-PASS and mE-PASS in another cohort of the same procedures (Group B, n = 313).

RESULTS

Areas under the receiver operating characteristic curve (AUC) for detecting in-hospital mortality in Group A were moderate at 0.75 for E-PASS, 0.69 for mE-PASS, and 0.69 for P-POSSUM. The predicted mortality rates of the models significantly correlated with severity of postoperative complications (ρ = 0.17, P = 0.011 for E-PASS; ρ = 0.15, and P = 0.027 for P-POSSUM). The AUCs were also moderate in Group B at 0.68 for E-PASS and 0.69 for mE-PASS. The predicted mortality rates significantly correlated with severity of postoperative complications (ρ = 0.18, P = 0.0018 for E-PASS; ρ = 0.17, and P = 0.0022 for mE-PASS).

CONCLUSIONS

The present study suggests that the predictive powers of general risk models may be moderate in pancreatic resections. A novel model would be desirable for these procedures.

Anaesthetic perioperative management of patients with pancreatic cancer

Pancreatic cancer remains a significant and unresolved therapeutic challenge. Currently, the only curative treatment for pancreatic cancer is surgical resection. Pancreatic surgery represents a technically demanding major abdominal procedure that can occasionally lead to a number of pathophysiological alterations resulting in increased morbidity and mortality. Systemic, rather than surgical complications, cause the majority of deaths. Because patients are increasingly referred to surgery with at advanced ages and because pancreatic surgery is extremely complex, anaesthesiologists and surgeons play a crucial role in preoperative evaluations and diagnoses for surgical intervention. The anaesthetist plays a key role in perioperative management and can significantly influence patient outcome. To optimise overall care, patients should be appropriately referred to tertiary centres, where multidisciplinary teams (surgical, medical, radiation oncologists, gastroenterologists, interventional radiologists and anaesthetists) work together and where close cooperation between surgeons and anaesthesiologists promotes the safe performance of major gastrointestinal surgeries with acceptable morbidity and mortality rates. In this review, we sought to provide simple daily recommendations to the clinicians who manage pancreatic surgery patients to make their work easier and suggest a joint approach between surgeons and anaesthesiologists in daily decision making.

POSSUM and P-POSSUM as predictors of postoperative morbidity and mortality in patients undergoing hepato-biliary-pancreatic surgery: a meta-analysis

BACKGROUND

Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) models are used extensively to predict postoperative morbidity and mortality in general surgery. The aim was to undertake the first meta-analysis of the predictive value of these models in patients undergoing hepato-biliary-pancreatic surgery.

METHODS

Eligible articles were identified by searches of electronic databases from 1991 to 2012. All data were specific to hepato-biliary-pancreatic surgery. Predictive value of morbidity and mortality were assessed by calculating weighted observed to expected (O/E) ratios. Subanalysis was also performed.

RESULTS

Sixteen studies were included in final review. The morbidity analysis included nine studies on POSSUM with a weighted O/E ratio of 0.78 [95 % confidence interval (CI) 0.68-0.88]. The mortality analysis included seven studies on POSSUM and nine studies on P-POSSUM (Portsmouth predictor equation for mortality). Weighted O/E ratios for mortality were 0.35 (95 % CI 0.17-0.54) for POSSUM and 0.95 (95 % CI 0.65-1.25) for P-POSSUM. POSSUM had more accuracy to predict morbidity after pancreatic surgery (O/E ratio 0.82; 95 % CI 0.72-0.92) than after hepatobiliary surgery (O/E ratio 0.66; 95 % CI 0.57-0.74), in large sample size studies (O/E ratio 0.90; 95 % CI 0.85-0.96) than in small sample size studies (O/E ratio 0.69; 95 % CI 0.59-0.79).

CONCLUSIONS

POSSUM overpredicted postoperative morbidity after hepato-biliary-pancreatic surgery. Predictive value of POSSUM to morbidity was affected by the type of surgery and the sample size of studies. Compared with POSSUM, P-POSSUM was more accurate for predicting postoperative mortality. Modifications to POSSUM and P-POSSUM are needed for audit in hepato-biliary-pancreatic surgery.

Risk-adjusted scoring systems in colorectal surgery

Consequent to recent advances in surgical techniques and management, survival rate has increased substantially over the last 25 years, particularly in colorectal cancer patients. However, post-operative morbidity and mortality from colorectal cancer vary widely across the country. Therefore, standardised outcome measures are emphasised not only for professional accountability, but also for comparison between treatment units and regions. In a heterogeneous population, the use of crude mortality as an outcome measure for patients undergoing surgery is simply misleading. Meaningful comparisons, however, require accurate risk stratification of patients being analysed before conclusions can be reached regarding the outcomes recorded. Sub-specialised colorectal surgical units usually dedicated to more complex and high-risk operations. The need for accurate risk prediction is necessary in these units as both mortality and morbidity often are tools to justify the practice of high-risk surgery. The Acute Physiology And Chronic Health Evaluation (APACHE) is a system for classifying patients in the intensive care unit. However, APACHE score was considered too complex for general surgical use. The American Society of Anaesthesiologists (ASA) grade has been considered useful as an adjunct to informed consent and for monitoring surgical performance through time. ASA grade is simple but too subjective. The Physiological & Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and its variant Portsmouth POSSUM (P-POSSUM) were devised to predict outcomes in surgical patients in general, taking into account of the variables in the case-mix. POSSUM has two parts, which include assessment of physiological parameters and operative scores. There are 12 physiological parameters and 6 operative measures. The physiological parameters are taken at the time of surgery. Each physiological parameter or operative variable is sub-divided into three or four levels with an exponentially increasing score. However, POSSUM and P-POSSUM over-predict mortality in patients who have had colorectal surgery. Discrepancies in these models have led to the introduction of a specialty-specific POSSUM: the ColoRectal POSSUM (CR-POSSUM). CR-POSSUM only uses six physiological parameters and four operative measures for prediction of mortality. It is much simplified to allow ease of use.