Evaluating surgical risk: the importance of technical factors in determining outcome.

A total of 113 patients having elective resection of the alimentary tract were studied prospectively to examine the relationship of pre-operative clinical and nutritional assessment to the development of major postoperative complications. In addition, the operating surgeon made a risk assessment on a linear analogue scale before and immediately after operation. Major complications developed in 28 patients (25 per cent). Age, weight loss and relative weight did not select high risk patients, but patients with a serum albumin of 29 g/l developed significantly more complications than those with higher levels (60 versus 22 per cent, P less than 0.05). Clinical assessment also selected some high risk patients but patients selected by the surgeon's pre-operative assessment did not develop significantly more complications than those not selected (38 versus 21 per cent). However, the surgeon's postoperative assessment did select patients at significantly increased risk, especially when compared with his pre-operative assessment. Of 38 patients who were selected pre-operatively as high risk or who increased their risk ranking postoperatively, 20 (53 per cent) developed complications, as opposed to only 6 of 65 patients (9 per cent) who were low risk or decreased their risk ranking (P less than 0.001). The surgeons changed their ranking postoperatively in 44 patients and in 36 (82 per cent) the reason given was the technical ease or difficulty of the procedure. Using receiver-operating characteristic curves, immediate postoperative assessment was superior to any pre-operative method of selecting high risk patients. Of 15 patients with normal serum albumin levels whose risk ranking increased postoperatively 6 (40 per cent) developed complications while none of the 7 patients with low serum albumin (high risk) who decreased their risk ranking developed complications. It is concluded that operative performance is the main factor in the development of postoperative complications and should be assessed in future studies of outcome.