Is Off-pump Coronary Artery Bypass Graft Surgery Cost-Saving?

Abstract

One of the challenges in comparing the cost of off-pump coronary artery bypass surgery to conventional coronary artery bypass graft surgery with cardiopulmonary bypass is that most data are from observational studies, not randomized controlled trials. Thus, cost differences observed between groups may not be attributable to the difference in surgical technique, but to the underlying patient characteristics that ultimately led the patient to be selected to receive one procedure or another. The purpose of this study was to control for patient selection effects in observational data and estimate reductions in costs and length of stay attributable to the off-pump coronary artery bypass procedure. We studied 1172 patients (245 off-pump coronary artery bypass and 927 coronary artery bypass graft) undergoing coronary bypass graft surgery via a median sternotomy at the Lehigh Valley Hospital between January 1, 1999 and June 30, 2000. Propensity scores were used to match patients who received off-pump coronary artery bypass surgery to similar coronary artery bypass graft surgery patients. Logistic regression was used to estimate propensity scores and select 181 patients from the coronary artery bypass graft group for comparison to patients in the off-pump coronary artery bypass group. Statistical comparisons of continuous outcomes were made using the Student t test after a transformation to natural log scale to correct skewness. Patients in the off-pump group tended to be treated by surgeons with more experience with off-pump surgery (p=0.0001), relatively older (p-0.001), had fewer diseased vessels (p=0.0001), did not have previous coronary artery bypass graft surgery (p=0.01), and had elective (p=0.0002) or urgent (p=0.002) surgery rather than emergent or salvage surgery. Propensity score matched coronary artery bypass graft patients had significantly longer total LOS (p=0.02), postoperative length of stay (p=0.03), and total costs (p=0.016) than patients who underwent off-pump coronary artery bypass surgery. After correcting for selection effects, off-pump coronary artery bypass surgery was associated with 12% lower total costs, 14% fewer total and postoperative hospital days. This suggests that coronary artery bypass surgery without cardiopulmonary bypass is cost-saving at a large academic community medical center. Future research should consider whether off-pump coronary artery bypass surgery is also cost-effective.