Risk assessment of acute renal failure after thoracoabdominal aortic aneurysm surgery

The authors sought a statistical model that permits the calculation of the chance of postoperative dialysis in patients undergoing thoracoabdominal aortic aneurysm repair. The preoperative risk of each individual patient was assessed.

Acute renal failure requiring dialysis after thoracoabdominal aortic aneurysm surgery is a common complication. Despite modern intensive care facilities, it continues to be associated with high morbidity and mortality.

The authors studied the influence of preoperative and intraoperative variables thought to be important clinically in the development of serious acute renal failure in 88 consecutive patients. Simple cross-clamping was used with the Crawford's graft inclusion technique without shunts or heparin. Statistical methods used include univariate and multivariate analysis (stepwise logistic regression analysis and Cox proportional hazard model).

The hospital mortality was 11.4% (n = 10). Long-term survival at 2 years was 78% (+/- 4.4), and at 5 years was 54% (+/- 5.3). A logistic regression model with only two explanatory variables to predict postoperative dialysis showed an almost perfect fit (chi 2 = 4.2, p = 0.84): the risk factors of postoperative dialysis were age (p = 0.003) and the preoperative serum creatinine level (p = 0.04). As determined by stepwise Cox regression analysis, postoperative dialysis also was a significant risk factor for late death (p = 0.002).

Using this statistical model, the chances of postoperative dialysis can be estimated exactly before operation; age and preoperative serum creatinine level are the only variables predictive for postoperative dialysis.