Effect of preoperative renal function on long-term survival after cardiac surgery

The study objective was to investigate the effect of renal failure on intermediate-term survival in cardiac surgery patients.

All patients aged 18 years or older undergoing coronary artery bypass grafting, valvular surgery, thoracic aortic surgery, or a combination of these from January 1, 2002 to December 1, 2005 were included. Data were obtained from the cardiac surgery and intensive care databases. Using a matching algorithm, the date of death was obtained from the National Death Index. The simplified Medical Diet for Renal Disease formula was used to calculate the estimated glomerular filtration rate, and the patients were stratified accordingly. An estimation of the effect of the preoperative renal function on the interval to death was determined using Cox regression analysis with and without cubic splines and polynomial regression. The long-term survival was described using the Kaplan-Meier product limit method.

A total of 5297 patients were included in the present study. The vital status of all patients was obtained at a mean of 2.9 years (range, 1-5) postoperatively. The actuarial 1-year survival rate was 96% ± 1%, and the 3-year survival rate was 92% ± 1%. The greatest early mortality occurred in the severe renal dysfunction group; however, the dialysis-dependent renal failure group showed increased mortality over time compared with the other groups. The lowest risk of death (longest interval to death) occurred with an estimated glomerular filtration rate of approximately 90 mL/min/1.73 m(2).

The results of our study have shown that preoperative renal dysfunction is an independent predictor of long-term mortality in cardiac surgery patients.