Context There have been recent calls for using hospital procedural volume as
a quality indicator for coronary artery bypass graft (CABG) surgery, but further
research into analysis and policy implication is needed before hospital procedural
volume is accepted as a standard quality metric.
Objective To examine the contemporary association between hospital CABG procedure
volume and outcome in a large national clinical database.
Design, Setting, and Participants Observational analysis of 267 089 isolated CABG procedures performed
at 439 US hospitals participating in the Society of Thoracic Surgeons National
Cardiac Database between January 1, 2000, and December 31, 2001.
Main Outcome Measure Association between hospital CABG procedural volume and all-cause operative
mortality (in-hospital or 30-day, whichever was longer).
Results The median (interquartile range) annual hospital-isolated CABG volume
was 253 (165-417) procedures, with 82% of centers performing fewer than 500
procedures per year. The overall operative mortality was 2.66%. After adjusting
for patient risk and clustering effects, rates of operative mortality decreased
with increasing hospital CABG volume (0.07% for every 100 additional CABG
procedures; adjusted odds ratio [OR], 0.98; 95% confidence interval [CI],
0.96-0.99; P = .004). While the association between
volume and outcome was statistically significant overall, this association
was not observed in patients younger than 65 years or in those at low operative
risk and was confounded by surgeon volume. The ability of hospital volume
to discriminate those centers with significantly better or worse mortality
was limited due to the wide variability in risk-adjusted mortality among hospitals
with similar volume. Closure of up to 100 of the lowest-volume centers (ie,
those performing ≤150 CABG procedures/year) was estimated to avert fewer
than 50 of 7110 (<1% of total) CABG-related deaths.
Conclusion In contemporary practice, hospital procedural volume is only modestly
associated with CABG outcomes and therefore may not be an adequate quality
metric for CABG surgery.