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Renal Function Predicts Limb Loss Following Infrainguinal Bypass in The Vascular Quality Initiative Database
Besma Nejim, Isibor Arhuidese, Rachel Lee, jasninder dhaliwal, Muhammad Fateeh, Satinderjit Locham, Hanaa Dakour Aridi, Husain AlShaikh, Mahmoud B Malas
Johns Hopkins School of Medicine, Baltimore, MD
Background: Patients with compromised renal function are known to suffer from worse postoperative outcomes. Prior single institutional-based studies suggested that lower extremity bypass (LEB) durability is affected by chronic kidney disease (CKD). The aim of this study is to evaluate the added risk for adverse outcomes, attributed to CKD, following LEB at the national level.
Methods: patients who underwent LEB in the Vascular Quality Initiative registry from 2003 to May 2015 were examined. Chronic Kidney Disease staging was determined by Glomerular Filtration Rate (GFR) calculated based on National Kidney Foundation guidelines. Primary outcome is ipsilateral major amputation at 30 months. Life tables, robust Cox proportional hazard clustered by centers and stratified by the year of surgery, and Wilcoxon log rank tests were implemented to estimate the hazard ratios and survival functions.
Results: Overall, 24,303 were identified during the study period. Of those, patients with GFR<15 or on dialysis (CKD5) were 1,435(6.2%), GFR 15-30 (CKD4): N=748(3.2%), GFR 30-60 (CKD3): N=6,147(26.3%) and GFR≥ 60 (CKD1/2): N=15,081(64.3%). Black race was more reported in CKD5 compared to other groups (CKD5: 27.7%, CKD4: 10.2%, CKD3: 9.6% and CKD1/2: 13.3%; P<.001). Diabetes mellitus was more prevalent in patients with CKD5 (CKD5: 75.8%, CKD4: 68.3%, CKD3: 53.3%, CKD1/2:41.5%; P<.001). The majority of patients presented with critical limb ischemia, particularly in advanced disease (CKD5: 93.2%, CKD4: 86.8%, CKD3: 72.0, CKD1/2: 65.3%; P<.001) (Table). Due to differential loss of follow-up in patients with CKD5, analysis time was restricted to 2.5 years. CKD5 was associated with 50% additional risk of amputation compared to CKD1/2 [adjusted Hazard Ratio (aHR): 1.50; 95%CI: 1.17-1.92; P=.001] (Figure). Critical limb ischemia as the indication for LEB conferred a fourfold increase in amputation risk [aHR(95%CI): 4.35(3.52-5.38); P<.001]. Other predictor of limb loss was black race [aHR(95%CI): 1.38(1.11-1.73); P=.005]. When compared to great saphenous vein, other veins and prosthetic grafts carried about 60% higher amputation risk [(aHR (95%CI): 1.62 (1.24-2.13), aHR(95%CI): 1.67 (1.44-1.94); both P<.001] respectively. Other predictors of limb loss were diabetes, immobilization and prior contralateral major amputation. Postoperative statin protected against limb loss [aHR(95%CI): 0.82 (0.71-0.95); P=.009]. Overall, dialysis was associated with nearly threefold increase in the incidence rates of limb loss [Incidence rate ratio (95%CI): 2.89 (2.45-3.39); P<.001]
Conclusion: In this cohort of patients undergoing LEB, renal function was an independent predictor of limb loss after controlling of all possible confounders. The risk for limb loss was significantly higher in patients with GFR<15 or on dialysis. Other important predictors were CLI at presentation, diabetes, black race and using conduits other than GSV. Identification of CKD patients’ characteristics that put them under higher risk for adverse limb outcomes can potentially refine decision making and ultimately provide better surgical care.
Table : Patient's characteristics per CKD stage.
| Patient’s Characteristics | CKD 5 (N=1,435; 6.2%) | CKD 4 (N=748, 3.2%) | CKD 3 (N=6,147; 26.3%) | CKD 1 (N=15,081; 64.3%) | P-value |
| Mean Age, (±SD) | 67.1(10.6) | 71.6(10.9) | 71.8(10.2) | 64.6(11.1) | <0.001 |
| Female gender | 516 (36.0) | 333 (44.5) | 2,432 (39.6) | 4,180 (27.8) | <0.001 |
| Black Race | 382 (27.7) | 76 (10.2) | 588 (9.6) | 1,992 (13.3) | <0.001 |
| Hispanic Ethnicity | 126 (8.8) | 30 (4.0) | 182 (3.0) | 475 (3.19) | <0.001 |
| Preop Ambulation : | |||||
| • Ambulatory | 475(52.5) | 479(64.6) | 4,461(73.0) | 11,788(79.0) | <0.001 |
| • Ambulatory w assistance | 492(34.7) | 203(27.4) | 1,337(21.9) | 2,485(16.7) | |
| • Wheelchair | 163(11.5) | 49(6.6) | 279(4.6) | 584(3.9) | |
| • Bedridden | 19(1.3) | 10(1.4) | 31(0.5) | 64(0.4) | |
| HTN | 1,375(95.9) | 724(96.9) | 5,731(93.3) | 12,564(83.7) | <0.001 |
| DM | 1,087(75.8) | 510(68.3) | 3,277(53.3) | 6,224(41.5) | <0.001 |
| Smoking | 1,048(73.1) | 569(76.3) | 4,843(78.9) | 13,095(87.3) | <0.001 |
| Critical limb ischemia at presentation | 1,323(93.2) | 640(86.8) | 4,372(72.0) | 9,683(65.3) | <0.001 |
| Hx CABG or PCI | 687(47.9) | 321(43.2) | 2,447(39.9) | 4,496(30.0) | <0.001 |
| Hx of PVI | 554(38.7) | 291(39.0) | 2,495(40.6) | 5,898(39.3) | 0.291 |
| Previous contralateral major amputation | 146(10.2) | 48(6.5) | 262(4.3) | 666(4.5) | <0.001 |
| Preoperative Aspirin | 996(69.5) | 542(72.7) | 4,335(7.9) | 10,626(70.8) | 0.489 |
| Preoperative p2y12 antagonists | 448(31.3) | 189(25.3) | 1,583(25.8) | 3,888(25.9) | <0.001 |
| Any aspirin or P2Y12 antagonists | 1099(76.7) | 584(78.3) | 4719(76.8) | 11495(76.6) | 0.777 |
| Preoperative statin | 981(68.5) | 541(72.4) | 4,377(71.3) | 10,109(67.4) | <0.001 |
| ACE inhibitor | 312(33.9) | 178(40.6) | 2,196(54.9) | 5,000(49.2) | <0.001 |
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