December 12, 2008

Carotid Artery Stenting in the Nation: The Influence of Hospital and Physician Volume on Outcomes

Todd R. Vogel, MD, MPH, Viktor Y. Dombrovskiy, MD PhD MPH, Paul B. Haser, MD, Alan M. Graham, MD.
UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ, USA.

Objectives: Multiple studies have investigated the effect of hospital and surgeon volume on the outcomes after open vascular procedures. Little information exists examining the impact of procedure volume on carotid artery stenting (CAS). We assessed national outcomes of CAS with respect to hospital and practitioner volume.
Methods: The 2005-2006 Nationwide Inpatient Sample was utilized. Selection criteria included: elective admission, a principal diagnosis of carotid artery stenosis (codes 433.10 and 433.11), and a CAS procedure (code 00.63) within two days of admission. Procedures were analyzed with respect to hospital volume, physician volume, and associated complications.
Results: 18,793 CAS interventions were identified. The top 25% was used to define high volume hospitals (>60 procedures) and practitioners (>30 procedures). The stroke rate after CAS was found to be significantly different between low and high volume hospitals (2.45%vs.1.77%, respectively; P=0.0061). Patients undergoing procedures in low volume hospitals were 1.4 times more likely to have a stroke (95% CI = 1.10-1.77). The stroke rate after CAS was also significantly different between low and high volume practitioners (2.32%vs.1.50%, P = 0.0067). Patients treated by low volume physicians were 1.6 times more likely to have a stroke (95% CI = 1.12-2.16). Resource utilization varied significantly between low and high volume hospitals (LOS in days: 1.68±2.18 vs.1.47±1.33,P= 0.0005; total charges: $32,507±21,046 vs.$30,402±20,806, P=0.0066) and practitioners (LOS: 1.75±2.28 vs.1.36±1.36;P<.0001; total charges: $34,164±22,379 vs.$24,041±15,233;P<.0001).
Conclusions: This analysis demonstrates that hospital and physician volume predict clinical outcomes and utilization after CAS. Higher volume hospitals and practitioners were significantly associated with lower post-procedure stroke rates and decreased hospital utilization. Patients undergoing CAS may significantly reduce their risk of post-operative stroke by selecting a high-volume hospitals and physicians.

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