Abstract 1816: Hospital Volume and Outcomes for Off-Pump vs On-Pump Coronary Artery Bypass Graft Surgery
Background: Coronary artery bypass surgery (CABG) performed off-pump has emerged in recent years as a less morbid alternative to on-pump CABG. However, the generalizability of prior studies has not been evaluated.
Methods: We conducted a retrospective study of 26,011 patients who underwent off-pump CABG and 99,344 who underwent on-pump CABG in the state of California during 2000 to 2004 in 124 hospitals, utilizing the California Patient Discharge Database. Generalized linear mixed models were used to compare in-hospital mortality and post-operative complications in patients undergoing on-pump CABG versus off-pump CABG, accounting sequentially for differences in patient and hospital characteristics. The relative mortality and complication rates for on-pump patients and off-pump patients were evaluated for hospitals across patient quartiles defined by hospital volumes (total off-pump CABG volume, percent off-pump CABG volume, total CABG volume).
Results: Off-pump patients were more likely to be non-white and less likely to have diabetes, hypertension and congestive heart failure. Mean length of stay for off-pump patients was shorter than for on-pump patients (8.7 vs. 9.6 days, p < 0.001). Overall, the unadjusted mortality and complication rates were lower in off-pump patients compared to on-pump patients (2.2 percent vs. 3.3 percent; 10.1 percent vs. 11.6 percent, respectively; p < 0.001). For hospitals in the highest percent off-pump CABG quartile, adjusted mortality and complications in off-pump patients were significantly lower than in on-pump patients (Odds ratio (OR) = 0.50; 95% CI, 0.42– 0.60; OR= 0.73, 95% CI, 0.66 – 0.80, respectively; p< 0.001), whereas for hospitals in the lowest percent off-pump CABG quartile, mortality and complications in off-pump patients were similar to those of on-pump patients (OR = 1.10; 95% CI, 0.72 – 1.67; OR= 0.92; 95% CI, 0.73–1.15, respectively; p > 0.05).
Conclusions: The lower rates of mortality and complications for patients undergoing off-pump is limited to hospitals specialized in off-pump CABG surgeries and cannot be generalized to other hospitals.