Background: Infections and sepsis are important determinants of mortality in patients with renal dysfunction. We studied the influence of preoperative renal function or postoperative acute renal failure (ARF) on the frequency of infections after open-heart surgery.
Methods: This was a retrospective analysis of 24,660 patients undergoing open-heart surgery from 1993 to 2000. Primary outcome was occurrence of serious infections after open-heart surgery; secondary outcome was hospital mortality.
Results: Overall incidence of infections after open-heart surgery was 3.3%. The infection rate was higher in patients with lower preoperative creatinine clearance, ranging between 2.2% and 10.0%. Regarding postoperative ARF, the frequency of infections was 58.5% in those patients requiring dialysis vs. 23.7% in those with ARF not requiring dialysis (P < 0.001); within each subgroup, however, the infection rates were similar regardless of the baseline renal function. In patients who did not develop ARF by either of our definitions, the infection rate was 1.6%. By multivariate analysis, preoperative renal function was an independent risk factor associated with infections [odds ratio (OR) for preoperative creatinine>1.2 mg/dL, 1.3; CI, 1.1 to 1.6]. The relationship between preoperative renal function and infection prevailed even after excluding the patients with postoperative ARF. The overall morality was 2.2%; the mortality in patients with serious infection was 31.7%.
Conclusion: Both preoperative renal dysfunction and postoperative ARF influence the frequency of serious infections after open-heart surgery. The infection rate was higher in patients with postoperative ARF regardless of the baseline renal function. However, preoperative renal dysfunction portended higher risk of infection, independent of the influence of postoperative ARF.