The Italian CABG Outcome Study: short-term outcomes in patients with coronary artery bypass graft surgery

Objective: During the last decade, a worldwide growing interest in evaluating performance of health services through 'outcome studies' took place. This study started in early 2002 and represents the first National Health System (NHS) experience to evaluate adjusted performance indicators at national level. The aim of this study was to compare 30 days mortality after coronary artery bypass graft (CABG) between cardiac surgery centres, adjusting by confounding risk factors. Methods: All patients, aged 15–99 years, undergoing a CABG intervention after 1st January 2002 in 82 participating centres were eligible for this observational longitudinal study. For each patient, data on severity and risk factors were collected (type of procedure, haemodynamic condition, co-morbidities, recent myocardial infarction and unstable angina, ventricular function, emergency condition, vital status at 30 days). Using a multiple logistic regression analysis the best predictive model was developed for risk-adjustment; a cross-validation procedure was applied; specific risk adjusted mortality rates (RAMR) were estimated. The overall study population was used as reference standard. Results: 34,310 isolated CABG were performed in 64 of the 82 participating centres. Thirty days mortality resulted 2.61%, ranging from 0.33 to 7.63%; eight centres presented a RAMR significantly lower and seven significantly higher than the reference. Conclusions: The study provides valid measures of the heterogeneity between outcomes of the Italian cardiac surgery centres, to support decision-making by NHS management and individual patients. Although not statistically significant, RAMR dropped from year 2002 to 2004 (2.8–2.4%) suggesting that this comparative outcome assessment can contribute to the improvement of performances in cardiac surgery.