Table 1 Standardized methods of risk assessment
Method of risk assessment | Definition | Advantages | Limitations |
|---|---|---|---|
Clinical prediction rules | The use of a scoring system based on patient- or procedure-related risk factors to quantify risk | Often cost-neutral | Estimates population risk for patient rather than providing an individualized risk assessment |
| Â | Â | Requires no specialist knowledge [34] | Â |
ASA-PS | Six-point scale used to grade patient according to comorbidities [35] | Inter-observer variability [39] | |
| Â | Â | Â | Poor sensitivity and specificity for prediction of morbidity and mortality on an individual patient basis [33, 40] |
Lee Revised Cardiac Risk Index (RCRI) | Scores patients according to six variables, including whether the surgery is high risk | Discriminates moderately well between patients at low versus high risk for cardiac events after mixed noncardiac surgery [42] | Designed to identify patients at risk of cardiac complications so may miss patients at risk of other complications who may benefit from PACU care |
| Â | Assesses cardiac risk [41] | Well validated | Â |
POSSUM | A more detailed scoring system with 18 components, 6 operative variables and 12 physiological variables [46] | A revision of POSSUM, the Portsmouth POSSUM [43] has been shown to be a better predictor of outcome in certain surgical settings [33, 44, 45] | Some variables cannot be ascertained until after surgery, making it of limited use for preoperative identification of patients who may benefit from PACU care |
| Â | Â | Variations in the model have been devised for specific patient groups, such as the Cr-POSSUM (colorectal), which has been shown to be a better predictor of outcome in this type of surgery [47] | Â |
Cardiopulmonary exercise testing | CPET is an integrative and quantitative measure of a patient’s cardiopulmonary reserve | Good evidence that CPET is useful to help predict perioperative morbidity and mortality and may aid triage to an appropriate level of postoperative care [48–50] | In 2008, 17% of Hospital Trusts in England had a CPET service, and a further 7% were in the process of setting one up [52] |
The assessment requires the patient to exercise (usually on a cycle ergometer) while oxygen consumption, carbon dioxide production, and other cardiorespiratory variables are measured | RCT in progress to further evaluate its use to stratify to appropriate level of postoperative care [51] |