Surgeon volume as an indicator of outcomes after carotid endarterectomy: an effect independent of specialty practice and hospital volume.
BACKGROUND
High-volume hospitals have been shown to have superior outcomes after carotid endarterectomy (CEA), but the contribution of surgeon volume and specialty practice to CEA outcomes in a national sample is unknown.


METHODS
Using the National Inpatient Sample for 1996 and 1997, 35,821 patients who underwent CEA (ICD-9-CM code 3812) and had data for unique surgeon identification were studied. Surgeons were categorized in terms of annual CEA volume as low-volume surgeons (< 10 procedures), medium-volume surgeons (10 to 29), and high-volume surgeons (> or = 30). Data from cardiac, general, neurologic, and vascular surgical practices were analyzed. In-hospital mortality, postoperative stroke, and prolonged length of stay (> 4 days) were the primary outcomes variables. Unadjusted and case-mix adjusted analyses were performed.


RESULTS
The overall in-hospital mortality was 0.61%. CEA was performed annually by high-volume surgeons in 52% of patients, by medium-volume surgeons in 30% of patients, and by low-volume surgeons in 18% of patients. Observed mortality by surgeon volume was 0.44% for high-volume surgeons, 0.63% for medium-volume surgeons, and 1.1% for low-volume surgeons (p < 0.001). The postoperative stroke rate was 1.14% for high-volume surgeons, 1.63% for medium-volume surgeons, and 2.03% for low-volume surgeons (p < 0.001). Surgeon specialty had no statistically significant effect on mortality or postoperative stroke. In the logistic regression model, increased risk of mortality was associated with emergent admission (odds ratio [OR] = 2.1; 95% confidence interval [CI] 1.6 to 2.8, p < 0.001), patient age > 65 years (OR = 2.0; 95% CI 1.3 to 3.1, p = 0.001), low-volume surgeon (OR = 1.9; 95% CI 1.4 to 2.5, p < 0.001), and COPD (OR = 1.8; 95% CI 1.3 to 2.5, p = 0.001). Low hospital CEA volume (< 100) was not a significant risk factor in the multivariate analysis.


CONCLUSIONS
More than 50% of the CEAs in the United States are performed by high-volume surgeons with superior outcomes. Health policy efforts should focus on reducing the number of low-volume surgeons, regardless of surgeon specialty or total hospital CEA volume.
Cowan
John A
JA
Department of Neurosurgery, University of Michigan Medical Center, Ann Arbor, MI, USA.
Dimick
Justin B
JB
Thompson
B Gregory
BG
Stanley
James C
JC
Upchurch
Gilbert R
GR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D002983:Clinical Competence; D016894:Endarterectomy, Carotid / Q000706:statistics & numerical data*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008511:Medicine; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications / Q000453:epidemiology; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D013038:Specialization; D020521:Stroke / Q000453:epidemiology