The challenge of departmental quality control in the reengineering towardsoff-pump coronary artery bypass grafting

Objective: Off pump coronary surgery is a major reengineering effort of the surgical systems. There are no perfect tools available to guide every cent re in the confrontation with the complete spectrum of risk and the limited number of events. This study analyses the use of a hospital mortality risk- stratifying system in the complete shift towards off pump CABG. Methods: Al l 535 off-pump CABG patients from January 1997 till September 2000 underwen t a comparison of their hospital mortality versus the EuroSCORE predictions . The mean risk predicted by the EuroSCORB was 4.5 +/-3% (range 0-14) and t he mean age was 65 +/- 10 years (range 36-89). The series includes 23 repea t procedures, also 77 patients with per oral or insulin-treated diabetes. T he number of distal anastomoses was 2.5 +/-1 and of arterial grafts 1.3 +/- 0.6. Results: The observed hospital mortality was 15 patients, 2.8% (Fisher exact test P=0.19 versus the EuroSCORE). The 1 and 3 month Kaplan-Meier su rvival, irrespective from hospital discharge, was 97.4 +/-0.7 and 97.2 +/-0 .7%, respectively. A cumulative risk-adjusted mortality plot is constructed . The area under the ROC curve was 0.886. A stepwise sampling of patients a ccording to increasing risk identified the difference between the EuroSCORE -predicted and observed hospital mortality for the complete spectrum of ris k. The P value of this difference was 0.06 for the grouping including all p atients from 0-5% risk (78% reduction), 0.04 for the grouping 0-8% risk (61 % reduction), and 0.05 for the grouping 0-11% risk (52% a reduction of risk ). The loss of statistical significant difference was due to the inclusion of the patients at extremely high risk. Conclusion: A hospital mortality ri sk-stratifying system can provide guidance but different and in depth appro aches are mandatory to improve the insight, certainly in the presence of a large spectrum of risk. (C) 2001 Elsevier Science B.V. All rights reserved.