Comparative Effectiveness of On-Pump versus Off-Pump Coronary Artery Bypass Grafting Among Elderly Patients: A Propensity Score-Matched Analysis

Abstract

Objective

Coronary artery bypass grafting (CABG) is a procedure used to restore blood flow to the heart for patients with coronary artery disease. The purpose of this study was to compare the effectiveness of on-pump versus off-pump CABG in elderly patients using the 2006–2008 5% national sample of Medicare administrative claims.

Study Design

A retrospective matched cohort study design was used. Elderly patients (over 65 years of age) undergoing CABG between July 1, 2006 and June 30, 2008 were identified using International Classification of Diseases, 9^th Revision, Clinical Modification codes. Propensity scores were used to match patients undergoing on-pump versus off-pump CABG in a ratio of 1:1. Outcomes assessed in this study include a composite cardiovascular end point consisting of postoperative acute myocardial infarction, stroke, or revascularization (percutaneous coronary intervention or CABG) and all-cause mortality. Descriptive statistics were reported along with Kaplan-Meier estimates. Postoperative risk of adverse cardiovascular outcomes and all-cause mortality in these groups was compared using Cox proportional hazards models.

Results

The matched sample consisted of 5356 patients (2678 patients in each group). The risk of composite outcome in the 2 groups was not significantly different (hazard ratio [HR] 0.915; P = 0.316). The risk of all-cause mortality was significantly lower among on-pump CABG patients compared with off-pump CABG patients (HR 0.544; P < 0.0001).

Conclusion

This study shows that elderly patients undergoing on-pump CABG have a lower risk of mortality as compared with those receiving off-pump CABG. Caution should be exercised when recommending elderly patients for off-pump CABG.