Do hospitals and surgeons with higher coronary artery bypass graft surgery volumes still have lower risk-adjusted mortality rates?
BACKGROUND
Studies that are the basis of recommended volume thresholds for CABG surgery are outdated and not reflective of recent advances in the field. This study examines both hospital and surgeon volume-mortality relations for CABG surgery through the use of a population-based clinical data set.


RESULTS
Data from New York's clinical CABG surgery registry from 1997 to 1999 (total number of procedures, 57 150) were used to examine the individual and combined impact of annual hospital volume and annual surgeon volume on in-hospital mortality rates after adjusting for differences in severity of illness. Significantly lower risk-adjusted mortality rates occurred above all annual hospital volume thresholds between 200 and 800 and above all surgeon volume thresholds between 50 and 200. The number needed to treat (NNT) at higher-volume providers to avoid a death was minimized for a hospital threshold volume of 100 (NNT=50) and a surgeon threshold volume of 50 (NNT=118). The risk-adjusted mortality rate (RAMR) for patients undergoing surgery performed by surgeons with volumes of > or =125 in hospitals with volumes of > or =600 was 1.89%. The RAMR was significantly higher (2.67%) for patients undergoing surgery performed by surgeons with volumes of <125 in hospitals with volumes of <600.


CONCLUSIONS
Higher-volume surgeons and hospitals continue to have lower risk-adjusted mortality rates, and patients undergoing surgery performed by higher-volume surgeons in higher-volume hospitals have the lowest mortality rates.
Hannan
Edward L
EL
Department of Health Policy, Management, and Behavior, School of Public Health, University at Albany, State University of New York, Albany, NY 12144-3456, USA. elh03@health.state.ny.us
Wu
Chuntao
C
Ryan
Thomas J
TJ
Bennett
Edward
E
Culliford
Alfred T
AT
Gold
Jeffrey P
JP
Hartman
Alan
A
Isom
O Wayne
OW
Jones
Robert H
RH
McNeil
Barbara
B
Rose
Eric A
EA
Subramanian
Valavanur A
VA
D001026:Coronary Artery Bypass / Q000401:mortality* / Q000706:statistics & numerical data*; D006302:Health Services Research; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006761:Hospitals / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D009518:New York / Q000453:epidemiology; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D019984:Quality Indicators, Health Care; D012017:Referral and Consultation; D012042:Registries / Q000706:statistics & numerical data; D020379:Risk Adjustment; D012307:Risk Factors; D013903:Thoracic Surgery / Q000592:standards / Q000706:statistics & numerical data*; D014600:Utilization Review