Journal of Vascular Surgery
Volume 49, Issue 6 , Pages 1416-1425, June 2009

Inferior outcomes of autogenous infrainguinal bypass in Hispanics: An analysis of ethnicity, graft function, and limb salvage

Presented at the New England Society for Vascular Surgery, Newport, RI, Oct 3-5, 2008.

Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass

Received 2 December 2008; accepted 10 February 2009.

Article Outline

Introduction

Recent evidence suggests disparities exist among racial groups with peripheral arterial disease (PAD). Hispanics (HI) are the fastest growing demographic in the United States, but little outcome data is available for this population. Therefore, we undertook this study to compare the results of autogenous infrainguinal bypass grafting in HI to Caucasians (CA) and African Americans (AA).

Methods

This was a comparative cohort study of prospectively collected registry data of infrainguinal bypass performed at a tertiary center. Patient demographics and comorbidities, operative indications, bypass graft characteristics, and postoperative courses were analyzed. Cumulative patency rates, limb salvage, mortality, and factors associated with these outcomes were determined using Kaplan-Meier analysis and Cox proportional hazards models.

Results

From January 1, 1985, through December 31, 2007, 1646 consecutive patients (1408 CA, 57 HI, and 181 AA) underwent 1646 autogenous infrainguinal reconstructions. HI and AA were younger and more often diabetic than CA but HI had less chronic renal insufficiency (CRI) and dialysis-dependence than AA. AA, but not HI, more commonly underwent bypass for critical limb ischemia (CLI) in comparison to CA (AA 90% vs CA 80%, P < .0001; HI 86%). HI and AA bypass grafts had inflow and outflow distal to that in CA. Perioperative mortality (2.3%) and morbidity were similar between groups. Five-year primary patency (± standard error [SE]) was significantly lower in HI compared to CA and similar to that in AA (HI 54% ± 7% vs CA 69% ± 1%, P = .02; AA 58% ± 4%). Cox proportional hazard modeling showed high-risk conduit, age <65, CLI, female gender, and AA race were risk factors for failure of primary patency. Secondary patency of HI grafts, unlike AA, was not different than that in CA. Five-year limb salvage (± SE) was significantly lower in HI compared to CA and similar to that in AA (HI 80% ± 6% vs CA 91% ± 1%, P = .004; AA 83% ± 3%). Hispanic ethnicity, CLI, high-risk conduit, age <65, CRI, female gender, and diabetes were significant predictors of limb loss.

Conclusion

Autogenous infrainguinal bypass surgery in HI is associated with primary patency and limb salvage inferior to that of CA and similar to that of AA, despite HI rates of CLI equivalent to CA and HI comorbidities less severe than AA. HI ethnicity was an independent predictor of limb loss. Our data provides evidence of outcome disparities in HI treated aggressively for their PAD. Further investigation with regard to biologic and social factors is required to delineate the reasons for these inferior outcomes in HI patients.

 

The Hispanic (HI) population is the most rapidly growing segment of the population within the United States. It is estimated that the HI population, now at 45 million, will grow to 103 million by 2050 and comprise 25% of the US population.1 Although reports focused on clinical treatment and outcomes in HI patients with vascular disease have been historically sparse, outcome disparities among HI with lower extremity occlusive disease have received recent attention. Based primarily on state discharge databases, HI have been found to be more likely than Caucasians (CA) to undergo amputation and HI ethnicity has been identified as an independent risk factor for amputation among patients with PAD.2, 3, 4, 5 The reasons for this are unclear. HI have been generally reported to have higher rates of diabetes than CA, although this alone does not seem to account for the higher incidence of amputation.4, 6 In a sample of New York and Florida hospital discharge databases, HI were less frequently offered lower extremity revascularization than CA despite higher rates of limb threatening ischemia.5

However, reports of the clinical presentation and outcomes of HI patients who actually undergo revascularization remain sparse. Furthermore, much of the existing data has been drawn from state or national discharge databases which often suffer from a lack of detailed clinical information, particularly regarding surgical reconstruction, and a lack of standardized surgical practice. Improved understanding of the risk factor profiles, severity of disease, and results of infrainguinal bypass is crucial to maximizing outcomes in HI. We previously reported that African American (AA) race is associated with inferior primary patency and limb salvage after autogenous infrainguinal bypass grafting compared to CA.7 We undertook this present study to compare the clinical presentation, bypass graft characteristics, graft patency, and limb salvage of autogenous infrainguinal bypass grafting in HI relative to CA and AA.

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Methods 

Patients 

Patients undergoing treatment of vascular disease at the Division of Vascular and Endovascular Surgery at the Brigham and Women's Hospital are prospectively entered into a computerized vascular registry. The registry collects data on patients with respect to demographics, comorbidities, indications for surgery, procedural characteristics, perioperative morbidity and mortality, medication use, graft patency, limb salvage (LS), and survival. From this registry, a retrospective cohort study was performed on all HI, AA, and CA patients who had undergone autogenous infrainguinal bypass grafting from January 1, 1985, to December 31, 2007. Hispanic ethnicity and racial status were recorded as designated by the patient at their hospital in-patient registration. The presence of comorbidities was defined by notation in the surgical or cardiology preoperative evaluation, except chronic renal insufficiency (CRI) which was defined as a preoperative creatinine ≥2.0. To avoid double counting of events in patients who may be predisposed to graft failure, the first limb bypass was chosen as the index procedure in patients who had undergone bilateral bypass. The index bypass may have been either a primary operation or a reoperative bypass done at our institution after a failed bypass at another hospital.

Operative technique 

The techniques of autogenous infrainguinal arterial reconstruction that are practiced by this group have been previously published.8, 9 The chosen inflow artery should be free of any significant proximal disease, and the outflow artery should be the least diseased vessel that provides the best distal perfusion to the foot. The conduit of first choice was the greater saphenous vein (GSV), which was used in either the reversed (when there was no significant change in the caliber of the vein) or the nonreversed (transposed or in situ) configuration. In the absence of usable GSV, arm veins (cephalic and basilic veins) and lesser saphenous veins were used as either single-segment or composite vein grafts. The criteria for an acceptable vein segment were a minimum diameter of 3.5 mm, easy distensibility with gentle irrigation, and absence of sclerotic or thrombosed areas. Vein segments that did not meet these criteria were excised or repaired. We defined “high risk” conduit as that which was anything other than single segment greater saphenous vein and included spliced vein, arm vein, or lesser saphenous vein. Completion angiography was routinely performed in all cases. We have also used intraoperative duplex scans in all cases except when accurate graft assessment is made impossible by difficult anatomy. We image both anastomoses and the length of the graft to look for evidence of vein structural abnormalities or a 2.5-fold velocity increase indicative of stenosis.

Postoperative care and graft surveillance 

After surgery, patients were placed on aspirin or clopidogrel on the day after operation and discharged on antiplatelet therapy unless contraindicated or advised against due to risk of bleeding in anticoagulated patients. Anticoagulation with heparin or Coumadin (Bristol-Myers Squibb, New York, NY) was used selectively if required for comorbid conditions or if the graft was deemed high risk by the surgeon. Appropriate patients are placed on beta-blockers and statins after their operation and maintained on them at discharge as advised by cardiology. Graft surveillance with a duplex ultrasonography scan was performed at 1 month and then at 3-month intervals for the first year and at 12-month intervals thereafter. A recurrence of symptoms, a change in the character of the graft or distal pulses, a decrease in the ankle-brachial index greater than 0.1, or pulse volume recording waveforms was considered an indication of possible graft stenosis prompting further evaluation. Duplex scan criteria of impending graft failure included decreased overall graft velocity (peak systolic velocity <25 cm/second in a normal-caliber graft) or a focal increase in velocity (peak systolic velocity >300 cm/second or an increase in peak systolic velocity in one segment of the bypass greater than three times that of an adjacent segment). Documented stenosis were evaluated with arteriography and repaired unless the patient was medically unfit for these procedures.

Outcomes 

Major morbidity was defined as postoperative myocardial infarction, pneumonia, acute renal failure, cerebrovascular event, and deep venous thrombosis/pulmonary embolism. Overall morbidity included wound complications, postoperative arrhythmia, and miscellaneous complications in addition to major morbidity. LS was defined as freedom from transtibial or above-knee amputation. Primary patency (PP), assisted primary patency (APP), and secondary patency (SP) rates were defined in accordance with the suggested reporting standards of the Society for Vascular Surgery/International Society for Cardiovascular Surgery Ad Hoc Committee.10

Statistical analysis 

Continuous variables were compared by using analysis of variance (ANOVA) for multiple groups and the t test between two groups. Categorical variables were compared by a 3 × 2 χ2 for multiple groups or Fisher's exact test for two groups. Comparison between two groups was only undertaken if the appropriate three-group comparison showed statistically significant differences. Graft patency, LS, and patient survival rates were analyzed with Kaplan-Meier curves and the log-rank test. Multivariate analysis of demographic, medical, and procedural factors affecting graft patency and LS was performed with Cox proportional hazard models. Variables tested in univariate analysis for potential inclusion in multivariate regression models included the following: comorbidities including age, gender, diabetes, smoking, hypertension, coronary artery disease, congestive heart failure (CHF), CRI, dialysis-dependence, or stroke; indications including claudication, rest pain, and tissue loss; graft characteristics including the level of graft inflow, level of graft outflow, and the use of “high-risk” conduit. Variables associated with loss of patency or amputation with a P value ≤ .20 on univariate analysis were included in the multivariate regression model. An α value of .05, corresponding to P = .05 and 95% confidence intervals, was used as a criterion for statistical significance. Loss to follow-up was defined as the last patient visit or contact after 18 months. Statistical computations were performed with SAS v9.1 (SAS Institute Inc, Cary, NC). Figs were generated with Intercooled STATA 7 software (Stata Corp, College Station, Tex).

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Results 

Demographics and comorbidities 

From January 1, 1985, through December 31, 2007, 1646 patients underwent autogenous infrainguinal reconstruction. Within this group there were 57 HI (3.5% of study population), while 181 AA and 1408 CA within the same time period comprised the remainder of the cohort. HI (mean age 65.2 years; range, 34-88) and AA (mean age 64.7 years; range, 31-86) were significantly younger than CA (mean age 68.8 years; range, 19-96). AA, but not HI, were more likely to be female than CA.

The HI comorbidity profile was unique relative to AA and CA. HI, like AA, had a greater prevalence of diabetes than CA. However, HI had rates of documented coronary artery disease (CAD) and CHF equivalent to CA while AA did not. Furthermore, HI had rates of CRI and dialysis-dependence significantly lower than AA and similar to CA (Table I).

Table I. Demographics and comorbidities
Hispanic n (%)African American n (%)Caucasian n (%)
Age(median)68a66c70
Gender (male/female)28/29(49/51)82/99(45/55)c855/553(61/39)
Diabetes36(63)a111(61)c649(46)
Smoking15(26)53(29)c540(38)
Hypertension40(70)140(77)c887(63)
Coronary disease28(49)66(37)c732(52)
CHF6(11)35(19)c129(9)
CRI8(14)b58(32)c153(11)
Dialysis-dependence6(11)b40(22)c79(6)
Stroke5(9)34(19)c156(11)

CHF, Congestive heart failure; CRI, chronic renal insufficiency.

aP < .05, Hispanic vs Caucasian.

bP < .05, Hispanic vs African American.

cP < .05, African American vs Caucasian.

Indication and bypass graft characteristics 

The indications for bypass were similar between HI and CA. The rates of critical limb ischemia (HI 86% vs CA 80%, P = .312) and tissue loss (HI 54% vs CA 47%, P = .223) were not significantly different between HI and CA at the time of bypass. By contrast, AA more commonly underwent bypass for critical limb ischemia (CLI) in comparison to CA (AA 91% vs CA 80%, P = .0004) and AA had higher rates of tissue loss than CA (AA 62% vs CA 47%, P = .0001).

Ninety percent of the bypasses in the AA cohort compared with 81% in the HI cohort and 83% in the CA cohort were primary operations. HI and AA more often had inflow distal to the common femoral artery in comparison to CA (HI 49% vs CA 34%, P = .028; AA 43% vs CA 34%, P = .0005). HI and AA also had a greater proportion of infrapopliteal outflow in comparison to CA (HI 74% vs CA 59%, P = .0328; AA 72%, vs CA 59%, P < .0001). There were no differences in the proportion of tibioperoneal and pedal distal sites for distal anastomosis. A single-segment saphenous vein was used as conduit in the great majority of operations (HI 86%, AA 83%, and CA 85%, P = .793). The remainder were performed with either autogenous composite vein, single-segment arm vein, or lesser saphenous vein (HI 14%, AA 17%, and CA 15%). Table II summarizes bypass graft characteristics.

Table II. Indications and bypass graft characteristics
Hispanic n (%)African American n (%)Caucasian n (%)
Critical limb ischemia49(86)163(90)b1119(80)
Tissue loss31(54)112(62)b663(47)
Claudication8(14)18(10)b289(21)
Primary reconstructions46(81)163(90)b1169(83)
Inflow
Common femoral29(51)a103(57)b924(66)
Superficial/profunda femoral15(26)36(20)312(22)
Popliteal13(23)42(23)172(12)
Outflow
Popliteal15(26)a50(28)b574(41)
Tibioperoneal32(56)96(53)705(50)
Pedal10(18)35(19)129(9)
Single segment GSV49(86)150(83)1191(85)
High risk conduit8(14)31(18)217(15)

GSV, Greater saphenous vein.

aP < .05, Hispanic vs Caucasian.

bP < .05, African American vs Caucasian.

Postoperative care, morbidity, and mortality 

Use of antiplatelet (ASA and/or clopidogrel), Coumadin, beta-blockers, and HMG-CoA reductase inhibitors (statins) on admission were not significantly different between groups (data not shown). HI were more likely than CA to be discharged on a beta-blocker but there were no differences in the use of antiplatelet, antithrombotic, or statin medications after bypass (Fig 1).

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  • Fig 1. 

    Use of antithrombotics and medications for control of cardiovascular risk factors among Caucasians (CA), African Americans (AA), and Hispanics (HI) after autogenous infrainguinal bypass.

Thirty-day mortality was not different between groups (HI 0%, AA 2.8%, and CA 2.3%, P = .468). Thirty-day major morbidity (HI 5.3%, AA 4.4%, and CA 7.9%, P = .462) and 30-day overall postoperative morbidity (HI 15.8%, AA 26.5%, and CA 21%, P = .252) were not different between groups. Thirty-day graft failure for HI was similar to that of CA while AA had an increased incidence of early graft failure compared to CA (AA 11% vs CA 5%, P = .012; HI 7%, Table III).

Table III. Perioperative morbidity and mortality
Hispanic n (%)African American n (%)Caucasian n (%)
Any morbiditya9(16)48(27)335(21)
Major morbidityb3(5)10(6)109(8)
30-day graft failure4(7)19(11)c77(5)
30-day mortality0(0)5(2.8)33(2.3)

aAny morbidity included wound complications, postoperative arrhythmia, and miscellaneous complications in addition to major morbidity.

bMajor morbidity was defined as postoperative myocardial infarction, pneumonia, acute renal failure, cerebrovascular accident, deep venous thrombosis/pulmonary embolism.

cP = .012, African American vs Caucasian.

Duration of follow-up was as follows: HI - mean 44.5 months, median 25.7 months, range, 0.1-204.1 months; AA - mean 35.9 months, median 20.7 months, range, 0.1-155.8 months; CA - mean 50 months, median 32.7 months, range, 0-266.5 months. There were no significant differences between groups. The number of patients lost to follow-up was not different between groups (HI 10.5%, AA 8.8%, and CA 9%). The proportion of patients who underwent one or more duplex bypass graft scans during the first postoperative year was not different between groups (HI 65%, AA 64%, and CA 58%, P = .195).

Long-term results of bypass 

The overall 5-year PP (± standard error [SE]) in HI was significantly lower than that of CA and similar to that of AA (HI 54% ± 7% vs CA 69% ± 1%, P = .02; AA 58% ± 4%, Fig 2). The overall 5-year APP (± SE) was also lower in HI compared to CA (HI 68% ± 7% vs CA 80% ± 1%, P = .027; AA 69% ± 4%, Fig 3). However, the secondary patency rates were not different between HI and CA while AA had inferior secondary patency compared to CA (AA 71% ± 4% vs CA 83% ± 1%, P = .0002; HI 76% ± 6%, Fig 4). Five-year LS (± SE) in HI was significantly lower than that of CA and similar to that of AA (HI 80% ± 6% vs CA 91% ± 1%; P = .0004; AA 84% ± 3%, Fig 5). Five-year survival and amputation-free survival were not different among groups. Five-year outcomes are summarized in Table IV.

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  • Fig 2. 

    Primary patency of autogenous infrainguinal bypass grafts in Caucasians (CA), African Americans (AA), and Hispanics (HI). The number at risk within each group is shown in the table below the curve.

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  • Fig 3. 

    Assisted primary patency of autogenous infrainguinal bypass grafts in Caucasians (CA), African Americans (AA), and Hispanics (HI). The number at risk within each group is shown in the table below the curve.

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  • Fig 4. 

    Secondary patency of autogenous infrainguinal bypass grafts in Caucasians (CA), African Americans (AA), and Hispanics (HI). The number at risk within each group is shown in the table below the curve.

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  • Fig 5. 

    Limb salvage after autogenous infrainguinal bypass grafting in Caucasians (CA), African Americans (AA), and Hispanics (HI). The number at risk within each group is shown in the table below the curve.

Table IV. Overall 5-year outcomes (± SE)b
Hispanic n (%)African American n (%)Caucasian n (%)
Primary patency54±7a58±4b69±1
Assisted primary patency68±7a69±4b80±1
Secondary patency76±671±4b83±1
Limb salvage80±6a84±3b91±1
Survival64±758±461±1
Amputation-free survival52±854±457±1

SE, Standard error.

aP < .05, Hispanic vs Caucasian.

bP < .05, African American vs Caucasian.

Significant factors associated with failure of PP (Table V), as well as APP and SP (Table VI), and LS (Table VII) were determined using Cox proportional hazard modeling. Hispanic ethnicity was an independent predictor of limb loss after infrainguinal autogenous bypass.

Table V. Predictors of loss of primary patency
VariableHazard ratio (95% CI)P value
High-risk conduit1.98(1.6-2.45)<.0001
Critical limb ischemia1.47(1.13-1.90).0004
Hispanic1.47(0.97-2.24).067
Age <651.36(1.13-1.64).035
African American1.33(1.02-1.73).035
Female gender1.24(1.03-1.49).023
Distal outflow1.09(0.94-1.26).27

CI, Confidence interval.

Table VI. Predictors of loss of assisted primary patencya
VariableHazard ratio (95% CI)P value
High-risk conduit1.94(1.5-2.52)<.0001
Critical limb ischemia1.74(1.25-2.44).0012
Hispanic1.63(0.99-2.68).055
Smoking1.49(1.18-1.88).0007
Age <651.48(1.17-1.87).001
African American1.47(1.07-2.01).016
Female gender1.33(1.06-1.67).013
Distal outflow1.25(1.02-1.54).033
Distal inflow0.98(0.83-1.17).839

CI, Confidence interval.

aThe significant predictors for loss of secondary patency were the same as those for loss of assisted primary patency though the hazard ratios were not identical and are not reported here.

Table VII. Predictors of limb loss
VariableHazard ratio (95% CI)P value
Critical limb ischemia4.22(2.02-8.81).0001
Hispanic1.87(1.0-3.49).0499
High-risk conduit1.81(1.27-2.6).0012
Age <651.55(1.12-2.13).008
Chronic renal insufficiency1.54(1.02-2.34).041
African American1.45(0.97-2.17).0736
Female gender1.38(1.01-1.89).045
Diabetes mellitus1.35(0.96-1.88).045
Distal outflow1.33(0.99-1.77).057
Distal inflow1.18(0.94-1.48).157

CI, Confidence interval.

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Discussion 

This study presents a novel characterization of HI undergoing infrainguinal bypass. HI had a unique comorbidity profile significant for a younger age at presentation and increased diabetes in comparison to CA and less CRI and dialysis-dependence than AA. HI, like AA, presented with a preponderance of infrageniculate disease but, unlike AA, did not present with increased CLI in comparison to CA. HI had inferior primary graft patency and limb salvage in comparison to CA. Hispanic ethnicity was an independent predictor of limb loss.

Previous studies, though sparse, suggest that limb loss disproportionally impacts HI. While administrative discharge data provide evidence of outcome disparities in HI with peripheral arterial occlusive disease, there is a paucity of data regarding the clinical presentation, bypass graft characteristics, and bypass results to guide the vascular surgeon in counseling and treating this population. To our knowledge, there have been only two reports which specifically addressed the results of bypass in the HI population.11, 12 These both reported results of infrapopliteal bypass only and one studied an entirely diabetic population.11 We therefore examined our experience in the broader group of HI undergoing autogenous infrainguinal bypass and compared it to our experience in CA and AA patients.

The comorbidity profile of HI was distinct from that of CA and AA. The younger age and increased diabetes in HI are consistent with the comorbidity profiles reported for HI with peripheral arterial disease (PAD) in larger population-based studies.5, 13, 14 Further study will be necessary to clarify the implications younger age and diabetes have on the virulence of PAD seen in HI patients. A key difference between HI and AA in our study was the significantly lower rate of CRI and dialysis-dependence in HI, a finding consistent with previous reports of the prevalence of CRI in these populations.15

Importantly, in our series, HI undergoing bypass did not have higher rates of critical limb ischemia or tissue loss in comparison to CA at the time of bypass. This stands in contrast to AA whose indication for bypass was more commonly CLI and who presented more often with tissue loss. This observation is similar to results of the series of infrapopliteal bypass by Rowe et al,12 but differs from population-based studies in which a larger proportion of HI presented with limb threat.5 As a tertiary referral center, our HI population may present earlier than HI in a center which serves a more indigent population. At least in our population, increased limb loss cannot be attributed to increased severity of ischemia at presentation.

To our knowledge, there is no previous information about the distribution or anatomic severity of PAD in HI at the time of revascularization. In our series, bypass grafts were reflective of a distal pattern of occlusive disease in HI similar to that in AA, in whom the predilection of arterial disease to the infrageniculate level is well described.16 The difficulty, both real and perceived, in reconstructing infrageniculate disease may contribute to the inferior results reported in HI with PAD. Lavery et al6 report that Mexican-American diabetics were four times as likely to have had a failed bypass or to be categorized as “not a bypass candidate” in comparison to non-Hispanic whites. Previous studies have documented the efficacy of distal origin and distal target bypass.17, 18 Continued excellence in infrageniculate revascularization should be emphasized to effectively treat both the AA and HI populations.

The 5-year PP and APP were significantly worse in the HI cohort compared to the CA cohort. This was not due to graft thrombosis within 30 days, which was equivalent between groups. Furthermore, conduit was not of inferior quality. Bypass grafts were just as frequently primary reconstructions performed with single-segment saphenous veins in HI as in CA. Loss of PP in HI is markedly inferior to that of CA in the period up to about 24 months. Thrombectomy and revision after graft failure were able to maintain a secondary graft patency in HI not statistically different from that of CA or AA. On multivariate analysis, high-risk vein conduit, the presence of critical limb ischemia, young age, female gender, and AA race were significant predictors of primary graft failure. Though associated with a hazard ratio for graft failure of almost 1.5, HI ethnicity did not meet statistical significance as a predictor of failure. Our analysis suggests that the inferior PP and APP in the HI cohort is related to their young age at presentation as HI were not significantly different from CA or AA on those other factors which predicted failure of patency. Further investigation into the impact and potential interplay of age, gender, and additional comorbidities in HI will help identify those at high risk for graft failure.

The most significant result from this analysis was that the 5-year limb salvage after bypass in HI was markedly worse than that of CA and similar to that of AA. Multivariate analysis identified HI ethnicity as an independent predictor of limb loss. To our knowledge, this is the first study identifying HI ethnicity as an independent predictor of limb loss after infrainguinal revascularization. There was a trend toward inferior outcomes after bypass in HI compared to CA in the study by Rowe et al.12 Toursarkissian et al11 combined AA and CA into a “non-Hispanic” group which had outcomes equivalent to that of HI. Given our results, we are not surprised that their outcomes in HI were equivalent to that of AA and CA combined.

Our data provides some insight into the reasons for increased limb loss in both HI and AA. Our analysis corroborates previous studies that have reported the negative impact of critical limb ischemia, young age, female gender, CRI, and diabetes on limb salvage.4, 19, 20, 21 The limb loss seen in AA is accounted for by these associated comorbidities. On the other hand, HI limb salvage was notably low despite the fact that HI rates of CLI were equivalent to CA and HI had a comorbidity profile less severe than AA, including less CRI. Furthermore, HI had secondary graft patency equivalent to that of CA. The possibility exists that this study is underpowered to detect a true difference in secondary patency that might contribute to limb loss in HI. Nevertheless, the data suggests that additional factors not available in our data must be implicated in the high risk of amputation among HI despite our aggressive stance toward revascularization and graft maintenance.

Inferior outcomes in HI and AA might involve a variety of sociologic and biologic mechanisms. The lower socioeconomic status of HI and AA and associated poor access to health care, as well as unhealthy behaviors and lifestyles, could have significantly impacted these populations.22, 23, 24 Language and cultural barriers as well as provider bias may also inhibit effective physician-patient communication and influence treatment decisions.25, 26, 27, 28 Overt provider bias is unlikely to have impacted this study because it was performed by an established group of vascular surgeons with a uniform, aggressive policy of limb salvage. Graft surveillance and use of medications were equivalent between groups. However, postoperative care is uniform only insofar as we can assess it with this study design. Further investigation with additional data would be required to determine if socioeconomic and cultural disparities could have influenced the preoperative care and postoperative courses of HI and AA.

Biologic mechanisms not routinely measured or accounted for in this study may also contribute to inferior outcomes in HI and AA. Given the existing evidence in HI and AA, metabolic syndrome and inflammation are excellent candidates for future investigation. Recent studies have elaborated the strong association between metabolic syndrome, insulin resistance, inflammation, and severity and progression of PAD.29, 30, 31, 32, 33, 34 HI and AA have high rates of obesity, metabolic syndrome, and inflammation.35, 36, 37, 38, 39 In addition, evidence shows that metabolic syndrome and vascular inflammation are intricately related, including within specific HI populations.30, 35, 40 Furthermore, inflammation has been strongly correlated with major adverse events after infrainguinal bypass including graft occlusion, the need for graft revision, and amputation.19 While our data does not address these mechanisms at this time, metabolic syndrome and inflammation in HI will be a focus of our future investigation.

The primary limitation of this study is the small sample size of the HI cohort. This reflects the demographics of our tertiary referral center and thus the results may not be generalizable to all other populations. Furthermore, there is inherent heterogeneity in the designation “Hispanic.” As an ethnicity, the term “Hispanic” encompasses a variety of racial, geographic, genetic, and cultural backgrounds. This makes it difficult to apply conclusions to all HI patients. All investigations of disparities and comparison of outcomes between ethnic groups suffer from this inherent limitation. In this study, ethnicity and race were recorded as designated by the patient on hospital admission. We believe this to be the most accurate and consistent method of identifying this group of patients.

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Conclusion 

Autogenous infrainguinal bypass in HI patients is associated with PP and LS inferior to that in CA and similar to that in AA, despite HI rates of CLI equivalent to CA and HI comorbidities less severe than AAs. Hispanic ethnicity is an independent risk factor for limb loss after autogenous infrainguinal bypass. Disparities in outcome thus persist in HI treated aggressively for PAD. Further investigation into the reasons for graft failure and limb loss, both sociologic and biologic, is warranted in order to improve results of treatment for PAD in this growing high-risk population.

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Author contributions 


Conception and design: MB, WR, MC

Analysis and interpretation: WR, CO, LN, MC, MB

Data collection: WR, CO, TC

Writing the article: WR, CO

Critical revision of the article: CO, LN, TC, MC, MB

Final approval of the article: WR, MB, LN, CO

Statistical analysis: WR, LN, CO

Obtained funding: MB, MC

Overall responsibility: MB

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We thank Julie Lombara for her invaluable assistance with the management of the vascular surgery registry.

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References 

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 Competition of interest: none.

PII: S0741-5214(09)00242-0

doi:10.1016/j.jvs.2009.02.010

Journal of Vascular Surgery
Volume 49, Issue 6 , Pages 1416-1425, June 2009

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