Abstract P105: Bypasses To Below-Knee Arteries May Expedite Amputation In Patients With Claudication

Abstract

Objective: Claudication is an early-stage subtype of peripheral artery disease that may result in surgical intervention. The purpose of this study was to compare the types of elective bypass in a population of Black and White patients with claudication and to identify actionable areas that may explain the higher limb amputation rates observed in Black patients. Methods: We identified Black and White patients undergoing elective infrainguinal bypass for claudication using data from the Vascular Quality Initiative registry (2011-2018). Distal bypass target was classified as 1) at or above the popliteal artery (above-knee) or 2) below the popliteal, including all tibial, peroneal, dorsalis pedis and tarsal/plantar arteries (below-knee). Graft conduit was categorized as vein or prosthetic. We calculated one-year risk of major lower limb amputation with 95% confidence intervals (CI) for all combinations of target and conduit, stratified by race. We then forced an intervention on the data to estimate the post-intervention incidence of amputation and the proportion of racial disparity eliminated and 95% CI if everyone received the gold standard treatment (above-knee, vein). Results: We identified 8,401 infrainguinal bypass revascularizations for claudication (12% Black/88% White); 82% were performed above-knee and 44% of those used a vein conduit. The remaining 18% of bypasses were to below-knee arteries, of which 78% used a vein conduit. The remaining 1,534 (18.3%) bypasses were to below-knee arteries, including 1,197 (78.4%) using vein and 330 (21.6%) using prosthetic material. One-year incidence of major limb amputation was 1.6% (1.3%,1.9%) among all grafts, 1.2% (1.0%,1.5%) in above-knee grafts, and 3.3% (2.4%,4.2%) in below-knee grafts. Black patients had higher incidence of amputation across bypass target/conduit groups compared to White patients; the difference was greatest for below-knee revascularizations (8.9%, 95% CI: 4.8%,12.3% v 2.1%, 95% CI: 0.9%,2.9%). Pre-intervention amputation incidence was 1.3% (1.0%,1.5%) in White patients and 3.6% (1.9%,5.2%) in Black patients. Overall amputation incidence decreased significantly after our gold standard intervention was applied for both White (1.0%; 0.7%,1.2%) and Black (2.0%; 0.7%,3.2%) patients. The risk difference (i.e. the disparity gap) between Black and White patients was lessened post-intervention by 56.8% (31.9%,116.3%). Conclusions: We observed risk of amputation higher than would be expected based on other studies of the natural history of claudication without bypass surgery; future work should identify the mechanisms that alter the natural history of claudication via open bypass surgery. Interventions below-knee or using a prosthetic graft were particularly harmful and their harm was concentrated in Black patients.