Predicting postoperative adverse events. Clinical efficiency of four general classification systems. The project perioperative risk.

BACKGROUND: The Project Perioperative Risk in Gothenburg is a prospective clinical-epidemiological study designed to elucidate factors affecting the perioperative risk in unselected adult patients undergoing elective general or orthopaedic surgery. In this report on postoperative adverse events of varying severity, the predictive ability of four simple classification systems, ASA physical status, patient age, surgical stress and a visual analogue scale for intuitively appreciated global risk (RISK-VAS), is described. METHODS: 1361 patients undergoing 1471 surgical procedures were subjected to a detailed and standardised preoperative assessment and classified according to ASA, age, procedure magnitude and RISK-VAS. Postoperative adverse events were prospectively registered during the entire hospital stay. RESULTS: The four classifications all correlated to postoperative adverse events. ASA physical status, RISK-VAS and patient age all appear to be more efficient in predicting severe than mild events, while surgical stress predicted severe events and mild ones equally well. CONCLUSION: The most efficient predictor of severe events appeared to be RISK-VAS, where a relative risk of 28.1 of acquiring a severe postoperative adverse event could be demonstrated for those who had a score of 4 or more compared with those who had scores less than 4.

Peroperative and immediate postoperative adverse events in patients undergoing elective general and orthopaedic surgery. The Gothenburg study of perioperative risk (PROPER). Part II.

All anaesthetic and surgical procedures impose a certain risk of complications. However, reliable estimates of this risk from prospective studies are rare. This study is a prospective clinical epidemiological study of 1361 consecutive patients subjected to elective general and orthopaedic surgery. These patients were followed from an extensive preoperative assessment to three months after the operation. In this report the peroperative and early postoperative period in the postoperative care unit or intensive care unit is described. General anaesthesia was given to 59% and regional/local anaesthesia to 41%. Adverse peroperative events occurred in 19%. The most common were circulatory events (11%), respiratory (4%), and allergic events (1%). Most events were of minor severity. However, with the official registration system, only 1 out of 8 events was detected. In the postoperative unit one or more adverse event was noted in 47% of the cases. These were dominated by circulatory (18.4%) and respiratory events (5.0%). CNS depression was noted in 6.8% of the cases. Most per- and postoperative event variables were highly correlated to the degree of surgical stress. In conclusion, a new concept for preoperative assessment and the registration of events during and after surgery was used. In this way, a large number of events of importance, not least for quality assurance, were found that would be missed with the official coding system. In a previous report we could show that even minor events affected the cost of care substantially.

The Gothenburg study of perioperative risk. I. Preoperative findings, postoperative complications.

The Gothenburg study of Perioperative Risk is a prospective clinical-epidemiological study designed to elucidate factors affecting the perioperative risk in unselected adult patients undergoing elective general or orthopaedic surgery. In this report reference data regarding preoperative characteristics and postoperative complications are presented. 1770 adult patients scheduled for elective general, urological, peripheral vascular or orthopaedic operative procedures were invited to a preoperative clinic. 81% agreed to participate and were assessed in a standardised way by means of questionnaires, interview, physical examination and laboratory screening. 82% had a previous or present condition in the medical history of some concern to the assessor. 71% had a finding of significance on physical examination. In 8% the assessment prompted further investigations or precautions. Throughout their hospital stay, all the 1361 participating patients were visited daily by an especially trained nurse with the task of registering the occurrence of complications. In 30% an untoward event occurred postoperatively--in 1% a severe one, in 21% a mild event, and in 8% an intermediate one. The complication rate was higher in vascular surgery (69%) than in orthopaedic (33%) and general/urological surgery (26%). Not only the severe and intermediate but also the mild complications affected the number of days in hospital.

Perioperative risk assessment. The Project Perioperative Risk (PROPER).

Surgical operations are preceded by an assessment of the anticipated risks for the patient due to the operation. The present assessment procedure is not optimally organised and the scientific base is weak. In this project a new organisation was tested that provides more relevant data on the risk and more optimal timing if the risk has to be modified. All elective patients from a defined geographical area (n = 1361) were seen one week before the operation for risk assessment. They were then followed up during and after the operation. About 30% of the operations were followed by complications. More than half of them were mild. Severe complications were rare. Three risk assessment classifications were tested. They were all fairly good estimators of the risk but had different properties. The next step in this project is to systematically evaluate the main risk-affecting factors to improve the quality of risk assessment.