Surgeon, Not Institution, Case Volume Is Associated with Limb Outcomes After Lower Extremity Bypass for Critical Limb Ischemia in the Vascular Quality Initiative

Abstract

Objectives

Studies from large administrative databases have demonstrated associations between institutional case volume and outcomes after lower extremity bypass (LEB). We hypothesized that increased institutional and surgeon volume would be associated with improved outcomes after LEB. Using a national, prospectively collected clinical database, the objective of this study was to determine the effects of both surgeon and institutional volume on outcomes after LEB.

Methods

The Vascular Quality Initiative (VQI) was queried to identify all LEB for critical limb ischemia or claudication between 2004–2014. Average annual case volume was calculated by dividing an institution or surgeon’s total LEB volume by the number of years they reported to VQI. Institutional and surgeon volumes were analyzed as continuous variables to determine the impact of volume on major adverse cardiac events (MACE), major adverse limb events (MALE), graft patency, and amputation free survival. Hierarchical regression models were used with cases clustered by surgeon and center. Time-dependent outcomes were evaluated with multivariable shared frailty Cox proportional hazards models.

Results

From 2004–2014, 14,678 LEB operations were performed at 114 institutions by 587 surgeons. Average annual institutional volume ranged from 1.0–137.5 LEBs per year, with a median of 26.9 [IQR 14–45.3]. Average annual surgeon volume ranged from 1–52 LEBs per year with a median of 5.7 [IQR 2.5–9.3]. Institutional LEB volume was not associated with major adverse cardiac or limb events, nor with loss of patency. However, average annual surgeon volume was independently associated with reduced MALE and improved primary patency. Institutional and surgeon volume did not predict MACE.

Conclusions

In contradistinction to previous studies, there was no relationship in this study between institutional LEB volume and outcomes after LEB. However, greater average annual surgeon volume was associated with improved primary patency and decreased risk of major adverse limb events. Open LEB remains a safe and effective procedure for limb salvage. Limb-related outcomes in CLI and claudication will be optimized if surgeons maintain adequate volume of LEB.