PREDICTION OF POSTOPERATIVE COMPLICATIONS AFTER ELECTIVE AORTIC-SURGERY USING STEPWISE LOGISTIC-REGRESSION ANALYSIS

Perioperative risk factors that contribute to postoperative morbidity have been identified for various forms of vascular disease, but it is not clear to what degree each type of disease contributes to morbidity when these diseases are seen in combination. We used stepwise logisti c regression analysis to determine the relative importance of 25 risk factors in predicting postoperative complications in 100 consecutive p atients undergoing elective intra-abdominal aortic surgery (59% aneury smal disease, 37% occlusive disease, 26% renal artery lesions). Thirty -one patients developed postoperative complications, including three d eaths. The most common complication was deterioration in renal functio n (17 patients, 24% of those at risk) followed by the need for prolong ed endotracheal intubation (>48 hours, 8%). All other events occurred uncommonly (4% or less). Stepwise logistic regression demonstrated fou r criteria that were significantly associated with complications. In d escending order of importance these were: renal artery occlusive disea se, intraoperative blood replacement, the preoperative APACHE 11 score , and a history of heavy smoking. Since both physiologic status and co morbid conditions contribute to morbidity and costs of elective vascul ar surgery, outcome studies must be adjusted to account for these preo perative characteristics. Additionally, since two-thirds of patients w ho have renal artery occlusive disease develop complications that prol ong hospitalization, our current methods of protecting the kidney duri ng ischemia should be improved to potentially reduce this cause of mor bidity.