Procedure rates and outcomes of coronary revascularization procedures in California and New York

Objective: Background data were obtained on all California hospitals performing coronary artery bypass grafting and percutaneous coronary intervention procedures and compared with reports published by the state of New York to develop a collaborative quality improvement program for cardiac surgery programs. Methods: The Patient Discharge Database of the Office of Statewide Health Planning and Development was queried for the years 1999-2001. In-hospital mortality and risk factors for coronary artery bypass grafting and percutaneous coronary intervention were obtained by using demographic data and International Classification of Diseases-Ninth Revision-Clinical Modification procedure and diagnosis codes. Risk models were developed by means of logistic regression analysis. Results: Overall coronary artery bypass grafting mortality was 33% higher and percutaneous coronary intervention mortality was twice as high in California compared with that in New York. Procedural volume (per unit population) was higher in New York. In high-volume California hospitals (> 300 procedures per year), coronary artery bypass grafting mortality was similar (California, 2.42%; New York, 2.25%). Excess coronary artery bypass grafting mortality (> 4.0%) occurred only in low-volume programs. Risk adjustment did not change the volume effect for coronary artery bypass grafting. No volume effect was noted for risk-adjusted percutaneous coronary intervention mortality. There were no obvious differences in risk factors between California and New York. Programs performing relatively fewer coronary artery bypass grafting procedures compared with percutaneous coronary interventions were found to have significantly higher coronary artery bypass grafting mortality after adjusting for volume effects. Percutancous coronary intervention volume is increasing and coronary artery bypass grafting volume is decreasing in both California and New York. Conclusions: Excess coronary artery bypass grafting mortality in California is related to the large number of low-volume programs. Excess percutancous coronary intervention mortality might be related to case selection or timing of intervention. A relationship between percutaneous coronary intervention volume and coronary artery bypass grafting mortality is suggested in which increasing percutaneous coronary intervention volume relative to coronary artery bypass grafting volume might have the effect of shifting patients with undefined higher risk characteristics to coronary artery bypass grafting.