Renal dysfunction before CABG increases costs and healthcare utilization

A database analysis found that patients undergoing CABG had higher costs and hospital resource utilization if they had renal dysfunction before undergoing surgery.

The researchers said optimizing renal function preoperatively could lower costs by approximately 6 percent (or $1,250) for every 10 mL/min improvement in creatinine clearance (CrCl).

Lead researcher Damien J. LaPar, MD, MSc, of the University of Virginia in Charlottesville, and colleagues published their results online in the Annals of Thoracic Surgery on Dec. 8.

“Multivariable regression analysis demonstrated highly statistically significant associations between preoperative CrCl and the outcomes of postoperative length of stay, total costs of hospitalization, postoperative hemodialysis, and operative mortality,” they wrote.

They noted that previous research showed that renal failure-related mortality rates were as high as 50 percent following cardiac surgery. Thus, clinicians have attempted to identify modifiable risk factors for developing post-operative renal failure, which is commonly assessed by evaluating a patients’ estimated CrCl.

In this analysis, the researchers evaluated 46,577 patients in the Virginia Cardiac Surgery Quality Initiative (VCSQI) data registry who underwent isolated CABG operations from Jan. 1, 2000 to Dec. 31, 2012. Patients were excluded if they were diagnosed with renal failure before the surgery or if they underwent concomitant valve or arrhythmia ablation procedures.

The VCSQI data registry includes patient-level data from 17 participating hospitals that voluntarily contributes its institutional data to the registry and the Society of Thoracic Surgeons national adult cardiac surgery database.

At baseline, the mean age was 65 years old, and 70.9 percent of patients were males. The median cardiac ejection fraction was 55 percent, the median serum creatinine level was 1.0 mg/ dL and the median estimated CrCl was 85 mL/min.

More than 96 percent of the surgeries were performed in the elective or urgent setting and fewer than 4 percent were performed in an emergency setting.

The most common outcomes after CABG were atrial fibrillation (17.2 percent of patients), prolonged ventilation (9.1 percent), renal failure (3.5 percent) and pneumonia (3.0 percent).

The median postoperative length of stay was 5 days, while the median cost of hospitalizations was $25,011.

The researchers said the estimated costs would increase by 10 percent, 20 percent and 30 percent with worsening of CrCl from a baseline of 80 mL/min to 60, 40 and 20 mL/min, respectively. In addition, as CrCl decreased, costs related to intensive care units, cardiac care units and blood products increased, while costs related to operating rooms and implants factored more heavily as determinants of total costs when CrCl increased.

The researchers cited a few limitations, including the study’s retrospective design, which is inherent to selection bias. They could also not determine a cause and effect relationship between preoperative CrCl and measured outcomes. They added that the total cost of hospitalization estimates may not be precise and that the drivers of cost estimates were not available, although the cost estimates were the same in all VCSQI hospitals.

“These data demonstrate that preoperative renal function is highly associated with the cost of performing CABG operations in a large, generalizable, multiinstitution cohort of patients,” the researchers wrote. “The assessment of preoperative renal function may be used to predict increased costs and hospital resource utilization through prolonged hospital admissions. Efforts such as proto- colized approaches to optimizing renal function before surgical myocardial revascularization has the potential to improve patient quality and the delivery of cost-conscious cardiac surgical care, with a potential savings of as much as 6% of hospitalization costs for every 10 mL/min improvement in creatinine clearance.”