Operator Volume and Outcome After Carotid Artery Stenting

Study Questions:

What is the association between operator and institutional volume and patient outcome after carotid artery stenting (CAS)?


The investigators linked Medicare claims from 2005-2009 to the Centers for Medicare and Medicaid Services’ CAS Database. The linked data were used to assess the association between 30-day mortality and past-year physician (0, 1-4, 5-9, 10-19, ≥20) and hospital (<10, 10-19, 20-39, ≥40) carotid stent volumes.


Among the 19,724 patients treated by 2,045 operators at 729 hospitals, the 30-day mortality risk was 1.8%. In the prior year, the median operator CAS volume was 9 (interquartile range, 4-19) and institutional volume was 23 (interquartile range, 12-41). Compared to physicians performing ≥20 CAS in the past year, lower CAS volumes were associated with higher adjusted risks of 30-day mortality: 1.4 for 0 past-year CAS, 1.3 for 1-4, 1.1 for 5-9, and 0.9 for 10-19. There was a similar inverse relationship between 30-day mortality and past-year CAS hospital volume as well as past-year hospital non-CAS volume.


The authors concluded that patients undergoing CAS by more experienced operators or at higher volume institutions have lower 30-day mortality.


The association between higher volume and better outcome has been demonstrated for many procedures. This study confirms prior work showing that most operators who perform CAS in the United States are low-volume operators, and outcomes are better when the procedure is performed by more experienced physicians at higher-volume institutions (Nallamothu BK, et al., JAMA 2011;306:1338-43).

Clinical Topics: Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Interventions and Vascular Medicine

Keywords: Carotid Arteries, Carotid Stenosis, Endarterectomy, Carotid, Geriatrics, Medicare, Mortality, Outcome Assessment (Health Care), Stents

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