Abstract 4174: Occult Renal Dysfunction: A Mortality Risk Factor in Patients Undergoing Coronary Artery Bypass Grafting
Introduction: Elevated preoperative serum creatinine (SCr) is considered an independent risk factor for postoperative mortality and morbidity in patients undergoing coronary artery bypass grafting (CABG). However, the impact of occult renal dysfunction (ORD) defined as an impairment of glomerular filtration rate with normal SCr is still unknown. Our aim is to analyse the effects of ORD on early outcomes after CABG.
Methods: This was a retrospective, observational, cohort study of prospectively collected data on 9159 consecutive patients with normal SCr levels undergoing CABG between April 1996 and February 2009. Patients were divided into two groups based on preoperative creatinine clearance (CrCl) level estimated by the Cockcroft-Gault equation: 5484 patients with a CrCl>60 ml/min and 3675 patients with a CrCl<60 ml/min (ORD group).
Results: Overall in-hospital mortality was 1 % (91 patients). ORD was associated with a doubling in the risk of operative mortality (1.4% vs 0.7%, OR 2.1, 95%CI 1.38 to 3.19, p=0.001), postoperative renal dysfunction (PRD, 5.1% vs 2.5%, OR 2.1 95%CI 1.68 to 2.27, p<0.0001), dialysis (0.8% vs 0.4%, OR 2, 95%CI 1.18 to 3.58, p=0.014) and stroke (1% vs 0.3%, OR 2.9, 95%CI 1.6 to 5.1, p<0.0001). In a multivariate analysis adjusting for preoperative risk factors, ORD was an independent predictor of mortality (OR 1.78, 95%CI 1.17 to 2.74), and PRD (OR 1.9, 95%CI 2.51 to 2.39) increasing with decreasing preoperative CrCl levels. After adjusting for propensity score as well as other possible confounders, ORD remained associated with a higher risk of death and PRD.
Conclusions: Occult renal dysfunction is an independent risk factor for early mortality and morbidity in patients undergoing CABG and CrCl should be used instead of SCr as a prognostic test for early clinical outcomes.