The role of hospital volume in coronary artery bypass grafting: Is more always better?

Objectives The goal of this study was to determine whether outcomes of none mergent coronary artery bypass grafting (CABG) differed between low- and hi gh-volume hospitals in patients at different levels of surgical risk. Background Regionalizing all CABG surgeries from low- to high-volume hospit als could improve surgical outcomes but reduce patient access and choice. " Targeted" regionalization could be a reasonable alternative, however, if su bgroups of patients that would clearly benefit from care at high-volume hos pitals could be identified. Methods We assessed outcomes of CABG at 56 U.S. hospitals using 1997 admini strative and clinical data from Solucient EXPLORE, a national outcomes benc hmarking database. Predicted in-hospital mortality rates for subjects were calculated using a logistic regression model, and subjects were classified into five groups based on surgical risk: minimal (<0.5%), low (0.5% to 2%), moderate (2% to 5%), high (5% to 20%), and severe (<greater than or equal to>20%). We assessed differences in in-hospital mortality, hospital costs a nd length of stay between low- and high-volume facilities (defined as great er than or equal to 200 annual cases) in each of the five risk groups. Results A total of 2,029 subjects who underwent CABG at 25 low-volume hospi tals and 11,615 subjects who underwent CABG at 31 high-volume hospitals wer e identified. Significant differences in in-hospital mortality were seen be tween low- and high-volume facilities in subjects at moderate (5.3% vs. 2.2 %; p=0.007) and high risk (22.6% vs. 11.9%; p=0.0026) but not in those at m inimal, low or severe risk. Hospital costs and lengths of stay were similar across each of the five risk groups. Based on these results, targeted regi onalization of subjects at moderate risk or higher to high-volume hospitals would have resulted in an estimated 370 transfers and avoided 16 deaths; i n contrast, full regionalization would have led to 2,029 transfers and avoi ded 20 deaths. Conclusions Targeted regionalization might be a feasible strategy for balan cing the clinical benefits of regionalization with patients' desires for ch oice and access. (J Am Coll Cardiol 2001;38: 1923-30) (C) 2001 by the Ameri can College of Cardiology.