The association between preoperative eGFR and outcomes in cardiac surgical patients

AIM: To study the relationship between preoperative renal function and outcomes in patients undergoing cardiac surgery. DESIGN, SETTING AND PARTICIPANTS: A retrospective descriptive study was performed on all patients who had coronary artery bypass, cardiac valve surgery and/or aortic arch surgery at a tertiary-referral hospital between January 2002 and December 2007. MAIN OUTCOME MEASURES: Clinical and demographic variables were compared across renal dysfunction categories, defined by glomerular filtration rate (eGFR) calculated using the modified Modification of Diet in Renal Disease (MDRD) equation. Logistic regression was used to assess the association between eGFR and outcomes, primarily in-hospital mortality. RESULTS: 7440 patients were included, with a mean age of 64 years and overall mortality of 1.6%. Across worsening renal function states, excluding patients receiving dialysis, patients were older, more likely to be women and to have comorbidities (particularly diabetes and vascular disease), as well as ventricular dysfunction, and to require emergency or more complex surgery. Unadjusted outcomes, as well as univariate and multivariate analysis, consistently demonstrated that odds ratios for adverse events increased with worsening renal function, even at moderate levels of dysfunction. CONCLUSIONS: Preoperative renal dysfunction is independently associated with mortality after cardiac surgery. This is consistent with the accumulating evidence supporting preoperative renal dysfunction as a powerful predictor of adverse outcomes.