Preoperative Renal Function Predicts Hospital Costs and Length of Stay in Coronary Artery Bypass Grafting

Background. Renal failure remains a major source of morbidity after cardiac surgery. Whereas the relationship between poor renal function and worse cardiac surgical outcomes is well established, the ability to predict the impact of preoperative renal insufficiency on hospital costs and health care resource utilization remains unknown. Methods. Patient records from a statewide The Society for Thoracic Surgeons (STS) database linked with estimated cost data were evaluated for isolated coronary artery bypass graft (CABG) operations (2000 to 2012). Patients with documented preoperative renal failure/dialysis were excluded. Preoperative renal function was determined using calculated creatinine clearance (CrCl). Multivariable regression analyses utilizing restricted cubic splines evaluated the continuous relationship between CrCl and risk-adjusted outcomes. Results. A total of 46,577 isolated CABG operations were evaluated with a median STS predicted risk of mortality score of 1.2% (interquartile range, 0.7% to 2.4%), including 9% off-pump CABG. Median CrCl was 85 mL/min (range, 2 to 120 mL/min), and median total cost was $25,011. After adjustment for preoperative risk factors, worsening CrCl (declining renal function) was highly associated with greater total costs of hospitalization (coefficient = -122, p < 0.001) and postoperative length of stay (coefficient = -0.03, p < 0.001). Furthermore, predicted total costs were incrementally increased by 10%, 20%, and 30% with worsening of CrCl from 80 mL/min to 60, 40, and 20 mL/min. As expected, decreasing CrCl was also associated with an increased risk-adjusted likelihood for hemodialysis and mortality (both p < 0.001). Conclusions. Preoperative renal function is highly associated with the cost of CABG. Assessment of renal function may be used to preoperatively predict cost and resource utilization. Optimizing renal function preoperatively has the potential to improve patient quality and costs by approximately 6% ($1,250) for every 10 mL/min improvement in creatinine clearance. (C) 2016 by The Society of Thoracic Surgeons