|Year : 2018 | Volume
| Issue : 1 | Page : 24-29
Race and outcomes of lower extremity revascularization for critical limb ischemia
Karen Massada1, Muhammad Rizwan2, Hanaa Dakour Aridi2, Mohammed Hasan3, Isibor Arhuidese4, Mahmoud B Malas2
1 Department of Surgery, Harlem Hospital Center, New York, NY, USA
2 Johns Hopkins Bayview, Vascular and Endovascular Research Center, Baltimore, MD, USA
3 Department of Surgery, University of Missouri-Kansas City, Kansas City, MO, USA
4 Department of Surgery, University of South Florida, Tampa, FL, USA
|Date of Web Publication||10-Jul-2018|
Mahmoud B Malas
Professor of Surgery, Johns Hopkins School of Medicine, Director of the Center for Research Excellence and Surgical Trials (CREST), The Johns Hopkins Hospital, Chief of Endovascular Surgery, Johns Hopkins Bayview Medical Center, Baltimore, MD
Source of Support: None, Conflict of Interest: None
INTRODUCTION: Studies have shown poor outcomes following infra-inguinal bypass in African-American patients compared with Caucasians. The aim of this study was to investigate the racial disparity in a cohort of patients who underwent infra-inguinal bypass surgery at our institute.
METHODS: We retrospectively reviewed data of all patients who underwent infra-inguinal bypass performed with autogenous vein grafts for symptomatic peripheral artery disease from 2007–2014 at a single tertiary care institution. Univariate (Chi-square test and Student's t-test) and multivariable analyses (logistic and Cox regression) were used to evaluate the association between race and the outcomes of mortality, primary and primary-assisted patency, and limb loss following infra-inguinal bypass.
RESULTS: The study included 412 autogenous bypass grafts, of which 312 (76%) were performed in Caucasians and 100 (24%) in African-Americans. African-American patients had significantly higher comorbidities including diabetes (74% vs. 57%, P = 0.002) and chronic kidney disease on dialysis (22% vs. 10%, P = 0.002) as compared with Caucasians. The majority of patients in both groups underwent bypass for critical limb ischemia (88% vs. 87%, P = 0.71). Mean follow-up time was 1.8 ± 1.8 years. The rates of major amputation were not significantly different between two groups (17% vs. 10%, P = 0.07). Moreover, no significant differences in primary and primary assisted were seen between African-Americans and Caucasians (hazard ratio [HR] [95% confidence interval [CI]: 0.90 [0.56–1.44], P = 0.66 and 1.21 [0.72–2.03], P = 0.46), respectively. Hyperlipidemia was shown to be significantly associated with primary-assisted patency, while diabetes was a significant risk factor for limb loss [HR (95% CI): 2.73 (1.26–5.93), P = 0.01).
CONCLUSION: In this study, there were no significant differences in bypass patency and limb salvage between African-Americans and Caucasians following infra-inguinal bypass over 5-year follow-up. These findings suggest that the outcomes of infra-inguinal bypass can be optimized in African-American patients with the use of autogenous vein conduits and comprehensive medical management including the control of diabetes and hyperlipidemia.
Keywords: Critical limb ischemia, lower extremity revascularization, outcomes, race
|How to cite this article:|
Massada K, Rizwan M, Aridi HD, Hasan M, Arhuidese I, Malas MB. Race and outcomes of lower extremity revascularization for critical limb ischemia. Vasc Invest Ther 2018;1:24-9
|How to cite this URL:|
Massada K, Rizwan M, Aridi HD, Hasan M, Arhuidese I, Malas MB. Race and outcomes of lower extremity revascularization for critical limb ischemia. Vasc Invest Ther [serial online] 2018 [cited 2018 Oct 15];1:24-9. Available from: http://www.vitonline.org/text.asp?2018/1/1/24/236295
| Introduction|| |
Advancement in the treatment of peripheral arterial disease (PAD) has resulted in significant reduction in amputation rates, ultimately improving patients' quality of life and overall outcomes. However, despite these advancements, minority racial groups, particularly African-Americans, have been be associated with poorer outcomes compared with their Caucasian counterparts.,,, Prior studies have reported that African-American patients are more likely to present with critical limb ischemia (CLI) and are less likely to undergo lower extremity revascularization procedures compared with Caucasians., Although there has been an overall increase in the use of endovascular revascularization in the management of PAD, African-American patients have been shown to be less likely to undergo endovascular treatment. Consequently, African-American patients are more likely to undergo amputation due to failed bypass or underutilization of revascularization for CLI when compared with Caucasians.,,
In addition, the lack of health insurance and low socioeconomic status have been demonstrated to be major contributors to the existing racial inequalities between African-Americans and Caucasians in the outcomes of surgical treatment for CLI., The goal of this study was to retrospectively review and compare the outcomes of infra-inguinal bypass in a cohort of African-American and Caucasian patients at our institution.
| Methods|| |
Data of all patients who underwent vein infra-inguinal bypass from January 2007 till August 2014 were retrospectively reviewed. Patients who received nonautogenous or prosthetic grafts were excluded from the study. Data was collected for patients self-designated as African-Americans or Caucasians. Patients who were self-designated as belonging to other races were excluded from this study. Patient and procedure information at the time of surgery were extracted from the electronic medical records. These included demographics (age, sex, and race), comorbidities (smoking history, hypertension, stroke, coronary artery disease (CAD), myocardial infarction (MI), diabetes mellitus (DM), hyperlipidemia, renal disease on dialysis, clinical presentation (intermittent claudication, CLI), preoperative medications (statins and aspirin), type of bypass (femoral-popliteal, femoral-tibial, popliteal-tibial, or below), and autogenous bypass vein source (reversed great saphenous vein, nonreversed great saphenous vein, small saphenous vein, basilic vein, cephalic vein, and spliced vein). The Transatlantic Inter-Society Consensus guidelines were followed and bypass surgery was offered to the patients with TASC C and D lesions, those with multiple disease levels and to the patients with previously failed endovascular treatments. Our primary bypass conduits were autogenous veins. We obtained veins primarily from the lower extremities and subsequently from the upper extremities. Prosthetic grafts were used only after vein conduits could not be harvested. About 5% of patients who underwent bypass surgery a tour institute received prosthetic conduits and were excluded from our analysis to minimize heterogeneity. This study was approved by Johns Hopkins Institutional Review Board and the requirement for individual patient consent was obtained since all data were de-identified.
Clinical assessment of distal pulses and foot integrity was performed at each follow-up visit. According to the standard protocol, patients also underwent surveillance duplex imaging of the bypass along with ankle–brachial indices and digital pressures at 1, 3, 12, 18 months and yearly after the bypass. Depending on venous conduit duplex findings, certain patients were brought back to the office more frequently for graft surveillance.
The primary outcomes in this study were mortality, primary patency (PP), primary-assisted patency (PAP), and amputation-free survival following lower extremity bypass. Deaths were verified by matching with the Social Security Death Index. PP and PAP were defined according to the Society for Vascular Surgery reporting standards. PP was defined as the time interval from graft placement until any intervention to maintain graft function. Primary-assisted patency was defined as the time interval from the time of graft placement to the graft thrombosis, including interventions designed to maintain the function of patent graft. Reintervention is defined as open or endovascular measures to maintain the patency. Data of outcomes collected included the occurrence of graft stenosis requiring intervention, thrombosis/occlusion amenable to intervention, thrombosis/occlusion not amenable to intervention, number of interventions required to maintain patency, and minor and major amputations.
Comparison of categorical variables between the two groups was performed using Pearson's Chi-square test, while continuous variables were compared using student's t-test. Kaplan–Meier curves were used to describe the viability of the bypass graft until reintervention to maintain primary and PAP and log-rank and Wilcoxon tests were used to test the equality of survival functions between Caucasians and African-Americans. Multivariable analyses (logistic regression, Cox regression) were employed to evaluate short- and long-term outcomes of lower extremity bypass and to study the association between race and primary outcomes while adjusting for potential confounders. Variables included in the multivariable models were chosen based on clinical relevance, prior literature, and univariable analyses. These included age, gender, race, smoking, history of hypertension, DM, CAD, chronic kidney disease (CKD), symptomatic status, hyperlipidemia, bypass level, graft type, and preoperative medications. Goodness-of-fit was assessed using the Hosmer–Lemeshow test. All analyses were performed using STATA statistical software version 14.1 (StataCorp, College Station, Texas). Statistical significance was accepted at P< 0.05.
| Results|| |
A total of 412 lower extremity bypasses using autogenous veins were performed during the study period. Of these, 312 (76%) bypasses were performed in Caucasians and 100 (24%) in African-Americans. African-American patients underwent the surgery at a younger age (66 ± 11 vs. 68 ± 12, P = 0.20), were more likely to be female (61% vs. CA: 35%, P< 0.001), and had more medical comorbidities including diabetes (74% vs. CA: 57%, P = 0.002), history of stroke (27% vs. 14%, P = 0.002), and CKD on dialysis (22% vs. 10%, P = 0.002) compared with Caucasians. CLI was the most common clinical presentation in both groups (88% vs. 87%, P = 0.71). Compared with Caucasians, the bypass configuration in African-American patients was femoropopliteal (28% vs. 33%; P = 0.12), femorotibial (35% vs. 40%; P = 0.12), and popliteal-tibial or below (37%vs. 26%; P = 0.12) [Table 1].
The mean follow-up time of this study was 1.8 ± 1.8 years. PP at 1, 3, and 5 years was 70%, 62% and 37% vs. 72%, 61% and 55% (P = 0.94) in African-Americans vs. Caucasians, respectively [Figure 1]. On the other hand, PAP in African-Americans versus Caucasians at 1, 3, and 5 years was 71%, 67%, and 41% vs. 83%, 72% and 67% (P =0.19), respectively [Figure 2]. Amputation free survival at 1, 3, and 5 years was 84%, 78% and 70% vs. 90%, 86% and 86%, (P = 0.08), respectively [Table 2] and [Figure 3]. There was no significant difference between African-American and Caucasian patients in terms of all-cause mortality rate (34% vs. 30%; P =0.51), need for reintervention to maintain patency (73% vs. 70%; P = 0.49), rate of infection (1% vs. 2%; P = 0.66), and amputation rates (17% vs. 10%; P = 0.07) [Table 3]. After adjusting for patients' demographics, comorbidities, and disease severity, there was no difference in the loss of primary [Hazard ratio (HR) 0.90 (95% CI: 0.56–1.44) P = 0.67] and PAP [HR 1.21 (95% CI: 0.72–2.03) P = 0.46] of the bypass grafts between African-Americans and Caucasians [Table 4] and [Table 5]. Significant risk factors associated with the loss of PAP on multivariable analysis included younger age (HR [95% CI]:0.97 [0.95–1.00]; P = 0.02) and hyperlipidemia (HR [95% CI]:1.73 [1.06–2.82]; P< 0.03). The hazards of amputation were higher for patients with DM (HR [95% CI]:2.73 [1.26–5.93]; P = 0.01) and for pop-tibial bypass level (HR [95% CI]: 2.84 [1.24–6.50], P = 0.01). However, increased age and male gender were associated with lower amputation hazards (HR [95% CI]:0.97 [10.95–1.00] and 0.52 [0.28–0.96], respectively) after adjusting for potential confounders [Table 6].
|Table 5: Cox regression analysis of the predictors of loss of primary-assisted patency|
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| Discussion|| |
Racial disparity in postoperative surgical outcomes in the United States has been well reported. In a retrospective study, Chew et al. reported the poor primary graft patency and limb salvage rates in African-Americans compared to Caucasians after infra-inguinal bypass with autogenous veins  and presented with gangrene as compared to Caucasians. Similarly, our cohort had similar findings of African-American patients undergoing lower extremity bypass at a younger age with advanced PAD as compared to Caucasians. However, in our study, there was no difference between the two racial groups in terms of graft patency, limb salvage, and mortality. In a multicenter PREVENT III trial, Chew et al. found that limb loss was attributable to black race and female gender synergistically. Graft failure was speculated to be due to the genetic predisposition of black patients' veins to undergo neointimal hyperplasia resulting in a nonfavorable biological response to venous bypass grafts. In our study, we did not analyze the severity of intimal hyperplasia in our patients, thus we were unable to determine whether the biographical response to bypass graft had any effect on the outcomes of this procedure.
Multiple studies have shown that amputation-free survival for all patients with CLI improves with a multidisciplinary care approach., A multidisciplinary team of a vascular, plastic, and a podiatric surgeon along with the aggressive management of the patient's comorbidities including dyslipidemia, diabetes, and atherosclerotic disease by the appropriate service improves amputation-free survival by greater than twofold when compared to the treatment by a standard wound care team., Managing atherosclerotic comorbidities in patients with CLI has been shown to reduce the risk of major amputations in this population. The management of patients' comorbidities is part of the standards of care in our practice which might have possibly reduced the disparity gap between African-Americans and Caucasians.
Perioperative success in lower extremity revascularization has been attributed to procedural factors, such as the selection of an adequate conduit, careful determination of anastomotic sites, as well as an enduring runoff bed. A previous study from our group has shown great limb salvage using autogenous graft. And in this study, we believe that using autogenous veins uniformly in our cohort greatly improved the outcomes in African-American patients. Of all the bypasses, 95% were performed using autogenous vein conduits. In the remaining 5%, synthetic grafts were used after vein conduit was explored and unsuccessful.
African-American patients have been shown be less likely to receive treatments according to established guidelines., This has led to question whether the continued existence of racial disparities in healthcare outcomes can be attributed to the scarcity of physicians from minority races who are treating patients from these minority races since unconscious bias among physicians exists regardless of race., Tiwari et al. reported that graft patency was similar between Caucasian and Afro-Caribbean who had equal access to health care and underwent lower extremity revascularization by bypass grafting for CLI at a London teaching hospital. However, these results are scarcely reproducible in the United States where matching for socioeconomic status, and insurance coverage has not reduced the disparity gap. Although our study did not include the socioeconomic information of patients, our results show that surgical outcomes in African-American patients can be optimal and similar to those of Caucasians.
Our study is not without limitations. The single-center retrospective nature of this study limits the generalizability of the results. Moreover, we do not have information about the socioeconomic status of patients so we could not adjust for it. In addition, the mean follow-up time was 1.8 ± 1.8 years thus long-term outcomes should be interpreted with caution.
| Conclusion|| |
African-American patients present with advanced PAD and higher comorbidities compared with Caucasians; however, in our center, there was no significant difference in outcomes following infra-inguinal bypass between the two groups including bypass patency and limb salvage over 5-year of follow-up. The results of this study suggest that outcomes of infra-inguinal bypass can be optimized in African-American patients with the use of autogenous veins conduits and a comprehensive interdisciplinary care team in patient management.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]