Abstract
Objectives
Black patients undergoing carotid endarterectomy (CEA) in the USA are more often symptomatic at presentation and have more comorbidities, compared to White patients. However, the impact of race on outcomes after CEA is largely unknown.
Methods
We identified CEA patients in the Vascular Quality Initiative (VQI) registry (2012–2017) and compared them by race (Black vs. White). All other non-White races (891, 1.4%) and Hispanics (2222, 3.4%) were excluded. We used multilevel logistic regression to account for differences in demographics and comorbidities. We assessed long-term survival using multivariable Cox regression. The primary outcome was perioperative stroke/death with long-term survival as a secondary outcome.
Results
We included 57,622 CEA patients; 2909 (5.0%) were Black, of whom 983 (34%) were symptomatic. Of the 54,713 White patients, 16,132 (30%) were symptomatic. Black patients, compared to White patients, had a higher vascular disease burden and were less likely to be operated on in a high volume hospital, or by a high volume surgeon. In addition, Black symptomatic patients, compared to White symptomatic patients, were more often operated on <2 weeks after the index neurological symptom (47% vs. 40%, P<.001). Perioperative stroke/death was comparable between Black and White patients (symptomatic: 2.8% vs. 2.2%, P=.2; asymptomatic: 1.6% vs. 1.3%, P=.2), as was unadjusted survival at 3-year, with 93% vs. 93%, P=.7, respectively. However, after adjustment, Black patients did experience better long-term survival compared to White patients (HR 0.8 [0.7–0.9] P=.01). On multilevel logistic regression, race was not associated with perioperative stroke/death (OR 1.0 [95% CI: 0.8–1.3] P=.98).
Conclusion
Despite the greater prevalence of vascular risk factors in Black patients and racial inequalities in surgical treatment, rates of perioperative stroke/death and unadjusted survival were similar between White and Black patients. Moreover, Black patients experienced better adjusted long-term survival after CEA.
INTRODUCTION
Despite ongoing efforts to reduce racial disparities in health care, the racial gap in patients undergoing carotid endarterectomy (CEA) remains. Eligible Black patients are less likely to undergo CEA, less often receive appropriate preoperative imaging studies, and experience a delay between diagnosis and procedure.1–3 In addition, Black patients have a higher disease burden, more often are symptomatic at presentation, and are more likely to have a stroke than a transient ischemic attack (TIA) as their presenting symptom.4 However, the impact of race on outcomes after CEA is conflicting.
While some early studies reported a higher risk for postoperative complications after CEA in Black patients,5–7 others found no association between race and stroke or mortality after CEA.8,9 However, most were limited by a small sample size or lacked detailed information on factors such as insurance type or hospital quality, which among patients undergoing abdominal aneurysm repair accounted for one fourth of racial differences in outcomes.10 Therefore, we sought to evaluate the association of race with early and long-term outcomes after CEA, using a contemporary cohort of CEA.
METHODS
The Beth Israel Deaconess Medical Center Institutional Review Board approved this project and waived the need for informed consent for the use of de-identified data in the registry.
Patients and registry
We performed a retrospective analysis on all CEA patients prospectively included in the Vascular Quality Initiative (VQI) registry between January 2012 and March 2017. The VQI is a North-American collaboration between 417 US and 3 Canadian centers, divided into 18 de-identified regional vascular quality groups, comprising over 3200 physicians. The goal of VQI is to assess quality of care and guide future quality improvements by monitoring over 200 predefined variables on patient demographics, operative details, and clinical outcomes, in addition to collecting data on perioperative and one-year follow-up data.11,12 VQI performs annual audits of discharge claims for each participating hospital to ensure that each physician entered all of their eligible procedures, thus preventing selection bias. Moreover, VQI retrieves mortality data from the Social Security Death Index (SSDI), which allows reliable perioperative mortality and long-term survival analysis.13 For more information, see: http://www.vascularqualityinitiative.org.
Of the 65,754 identified CEA patients, we excluded those missing data on race (n.=.1,457, 2.2%) or on preprocedural neurological symptom (n.=.264, 0.4%), as well as patients with a race other than White or Black (n.=.891, 1.4%), those of Hispanic ethnicity (n.=.2,222, 3.4%), patients with concomitant cardiac surgery (n.=.1,139, 1.7%), emergency cases (n.=.447, 0.7%), and those with an ipsilateral occluded carotid artery (n.=.1,431, 2.2%), or prior ipsilateral CEA, i.e. ‘redo’ CEA (n.=.1,160, 1.8%). This resulted in a study sample of 57,622 patients, of whom 2,909 (5.0%) were Black.
Endpoints and definitions
Our exposure variable was race, classified as non-Hispanic White and non-Hispanic Black, hereafter referred to as White and Black. We defined symptomatic patients as those having a preprocedural ipsilateral neurologic event, which included any ipsilateral hemispheric or ocular transient ischemic attack (TIA) or any ipsilateral stroke.12,14 We classified all patients with a preoperative hemoglobin (Hb) < 11g/dL as having moderate anemia, based on the WHO guideline.15 We assessed center and surgeon volume by stratification into volume quintiles based on their corresponding average annual volume of procedures.
Our primary endpoint was any in-hospital stroke or any death within 30-days, hereafter referred to as perioperative stroke/death. Secondary endpoints were 30-day mortality, long-term survival, and in-hospital events of: stroke, myocardial infarction (MI), cranial nerve injury (CNI), any return to the operating room, length of stay (LOS) >2 days, and any failed discharge to home. The definition of stroke included any new motor or sensory loss, speech abnormality, or documentation of any other neurologic symptom related to the right or left hemisphere, lasting at least 24 hours. MI included electrocardiogram changes characteristic for MI, or elevated troponin levels. VQI defined CNI as any CNI that began after the CEA and persisted until the time of discharge. We calculated LOS as the number of days between surgery and discharge. We classified failed discharge home as any patient that was admitted from home, but discharged to a place other than home.
Statistical analysis
We presented categorical variables as counts and percentages, continuous variables as mean ± standard deviation (SD), or median and interquartile range (IQR), where appropriate. To assess differences between Black and White patients in our univariate analysis we used χ2 and Fisher’s exact tests for categorical variables and Student’s t-test and Mann-Whitney U test for continuous variables, where appropriate. To evaluate the timing of CEA in symptomatic patients, we stratified symptomatic patients as: those operated on <2 weeks vs. those operated on ≥2 weeks after their index neurological symptom.
Using multilevel logistic regression analysis, which allowed for random variation at the center level, we assessed the impact of race on perioperative outcomes, after adjustment for significant predictors and confounders, according to the methodology of purposeful selection, which combines known risk factors with significant confounders and covariates with a P < .2 on univariate screen.16 Additionally, we used multilevel logistic regression to identify independent risk factors for perioperative stroke/death, regardless of patients’ race, whereafter we evaluated whether the association between these factors and perioperative stroke/death differed significantly between Black and White patients, using an interaction term.
For our survival analysis, we performed multivariable Cox regression, which adjusted for significant predictors and confounders of long-term survival, which, based on the Schoenfeld residuals test, included time-dependent variables for non-proportional covariates included in the model. We used our Cox regression model to graph the survival functions for Black and White patients.
Within our multilevel logistic and Cox regression analyses, we assigned dummy variables to account for patients missing data on insurance status (5.6% missing), or ambulatory status (5.7% missing), or contralateral carotid stenosis degree (12.4% missing). For all analyses, we considered P-values <.05 significant and used Stata/SE 12, StataCorp LLC, College Station, Texas.
RESULTS
Baseline characteristics
Of the 2,909 Black patients, 983 (34%) were symptomatic, whereas of the 54,713 White patients, 16,132 (30%) were symptomatic (P < .001). Overall, regardless of symptom status, Black patients were younger, more likely to be female, on self-pay or Medicaid insurance, functionally dependent, current smokers, have insulin dependent diabetes mellitus (IDDM), congestive heart failure (CHF), hypertension, anemia, end-stage renal disease, or a prior amputation, but less likely to have chronic obstructive pulmonary disease (COPD), a prior coronary intervention, or to be operated on by a high volume surgeon or in a high volume center (Table IA).
Table IA.
Differences in patient characteristics between White and Black patients undergoing carotid endarterectomy, stratified on symptom status.
| Symptomatic patients | P-value | Asymptomatic patients | P-value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| (N = 17,115) | (N = 40,507) | |||||||||
| White | Black | White | Black | |||||||
| N | % | N | % | N | % | N | % | |||
| N | 16132 | 94 | 983 | 5.7 | 35581 | 95 | 1926 | 4.8 | ||
| Age Years (Mean, SD) | 70.4 | 10.0 | 67.3 | 10.4 | <.001 | 70.7 | 9.1 | 68.4 | 9.7 | <.001 |
| Age ≥ 80 years | 3221 | 20 | 129 | 13 | <.001 | 6539 | 17 | 250 | 13 | <.001 |
| Women | 6064 | 38 | 476 | 49 | <.001 | 15348 | 40 | 1052 | 55 | <.001 |
| Insurance status* | <.001 | <.001 | ||||||||
| Commercial | 5452 | 34 | 345 | 35 | 12799 | 33 | 683 | 36 | ||
| Medicare | 8649 | 54 | 428 | 44 | 21891 | 57 | 959 | 50 | ||
| Medicaid | 529 | 3.3 | 91 | 9.3 | 1040 | 2.7 | 141 | 7.3 | ||
| Military/VA | 137 | 0.8 | 7 | 0.7 | 246 | 0.6 | 17 | 0.9 | ||
| Self pay | 353 | 2.2 | 42 | 4.3 | 392 | 1.0 | 37 | 1.9 | ||
| Foreign insurance | 106 | 0.7 | 1 | 0.1 | 46 | 0.1 | 3 | 0.2 | ||
| Missing | 906 | 5.6 | 69 | 7.0 | 2167 | 5.6 | 86 | 4.5 | ||
| Dependent ambulatory status* | 1941 | 13 | 205 | 23 | <.001 | 2654 | 7.3 | 270 | 15 | <.001 |
| Current smoker | 4605 | 29 | 377 | 39 | <.001 | 10176 | 26 | 560 | 29 | .01 |
| Obese (BMI≥30) | 5535 | 34 | 315 | 32 | .2 | 13102 | 34 | 705 | 37 | .02 |
| Insulin dependent DM | 1960 | 12 | 208 | 21 | <.001 | 4526 | 12 | 417 | 22 | <.001 |
| Hypertension | 14050 | 87 | 928 | 95 | <.001 | 34302 | 89 | 1835 | 95 | <.001 |
| Coronary artery disease | 3801 | 24 | 208 | 21 | .1 | 10833 | 28 | 498 | 26 | .03 |
| Prior CABG/PCI | 895 | 5.9 | 36 | 3.9 | .02 | 2799 | 7.7 | 91 | 4.9 | <.001 |
| CHF | 1537 | 9.5 | 135 | 14 | <.001 | 3975 | 10 | 280 | 15 | <.001 |
| COPD | 3612 | 22 | 179 | 18 | .003 | 8935 | 23 | 347 | 18 | <.001 |
| Any prior non-coronary endovascular intervention | 1049 | 6.5 | 76 | 7.7 | .1 | 3911 | 10 | 226 | 12 | .02 |
| Any non-cardiac arterial bypass for occlusive disease | 717 | 4.4 | 52 | 5.3 | .2 | 2487 | 6.4 | 143 | 7.4 | .1 |
| Prior major amputation | 98 | 0.6 | 23 | 2.3 | <.001 | 306 | 0.8 | 45 | 2.3 | <.001 |
| GFR > 60ml/min | 4726 | 30 | 309 | 33 | .1 | 12219 | 32 | 729 | 40 | <.001 |
| End stage renal disease | 160 | 1.0 | 36 | 3.7 | <.001 | 410 | 1.1 | 97 | 5.0 | <.001 |
| Moderate anemia (Hb < 11g/dL) | 1649 | 10 | 229 | 23 | <.001 | 3828 | 10 | 449 | 24 | <.001 |
| Preoperative medication | ||||||||||
| ASA | 13280 | 82 | 798 | 81 | .4 | 32068 | 83 | 1572 | 82 | .1 |
| P2Y12-antagonist | 5940 | 37 | 381 | 39 | .2 | 10656 | 28 | 599 | 31 | .001 |
| Any antiplatelet | 14365 | 89 | 867 | 88 | .5 | 33979 | 88 | 1684 | 88 | .4 |
| Dual antiplatelet | 4855 | 30 | 312 | 32 | .3 | 8745 | 23 | 487 | 25 | .01 |
| Statin | 13078 | 81 | 826 | 84 | .02 | 30959 | 80 | 1536 | 80 | .6 |
| Beta-blocker | 8649 | 54 | 559 | 57 | .048 | 22595 | 59 | 1151 | 60 | .3 |
| Ipsilateral carotid stenosis (70–99%) | 13134 | 83 | 812 | 84 | .3 | 34861 | 92 | 1708 | 92 | .3 |
| Contralateral carotid occlusion* | 520 | 3.6 | 23 | 2.6 | .1 | 1890 | 5.7 | 90 | 5.4 | .6 |
| Symptomatic | ||||||||||
| Ipsilateral TIA | 8659 | 54 | 350 | 36 | <.001 | – | – | – | – | – |
| Ipsilateral stroke | 7674 | 48 | 641 | 65 | <.001 | – | – | – | – | – |
| Rankin scale score (median, IQR) | 1 (0–2) | 1 (1–3) | <.001 | |||||||
| Rankin scale score (mean, SD) | 1.3 | 1.2 | 1.7 | 1.4 | <.001 | – | – | – | – | – |
| Time between neurological event and CEA* | <.001 | |||||||||
| ≥2 weeks | 8931 | 60 | 485 | 53 | ||||||
| <2 weeks | 6007 | 40 | 423 | 47 | ||||||
| Time between ipsilateral TIA and CEA* | .07 | |||||||||
| ≥2 weeks | 4858 | 62 | 181 | 56 | ||||||
| <2 weeks | 3039 | 39 | 140 | 44 | ||||||
| Time between ipsilateral stroke and CEA* | .004 | |||||||||
| ≥2 weeks | 4202 | 58 | 309 | 52 | ||||||
| <2 weeks | 3025 | 42 | 284 | 48 | ||||||
| Prior contralateral CEA | 1306 | 8.1 | 65 | 6.6 | .1 | 6324 | 16 | 223 | 12 | <.001 |
| Prior radiation | 230 | 1.4 | 10 | 1.0 | .3 | 525 | 1.4 | 23 | 1.2 | .6 |
| Prior neck surgery | 474 | 3.1 | 23 | 2.5 | .3 | 1549 | 4.3 | 59 | 3.2 | .04 |
| Elective vs. urgent procedure | 11969 | 74 | 696 | 71 | .02 | 33659 | 95 | 1769 | 92 | <.001 |
| Highest quintile volume surgeon | 3215 | 20 | 127 | 13 | <.001 | 8149 | 21 | 288 | 15 | <.001 |
| Lowest quintile volume surgeon | 3442 | 21 | 268 | 27 | <.001 | 7060 | 18 | 428 | 22 | <.001 |
| Highest quintile volume center | 3408 | 21 | 142 | 14 | <.001 | 7586 | 20 | 260 | 14 | <.001 |
| Lowest quintile volume center | 3192 | 20 | 224 | 23 | .02 | 7336 | 19 | 481 | 25 | <.001 |
SD: standard deviation, IQR: interquartile range, COPD: chronic obstructive pulmonary disease, BMI: body mass index, IDDM: insulin dependent diabetes mellitus, CHF: congestive heart failure, CEA: carotid endarterectomy, GFR: glomerular filtration rate, Hb: hemoglobin, ASA: acetylsalicylic acid, TIA: transient ischemic attack, EEG: electro encephalography,
>5% missing data.
Additionally, symptomatic Black patients more often had a preprocedural ipsilateral stroke compared to symptomatic White patients (65% vs. 48%, P < .001), with a higher preprocedural Modified Rankin Scale score (mean (SD): 1.7 (1.4) vs. 1.3 (1.2), P < .001, Table IA). Moreover, symptomatic Black patients were more likely operated on <2 weeks vs. ≥2 weeks of their index neurological symptom, compared to symptomatic White patients (47% vs. 40%, P < .001). Similarly, among patients with a preprocedural ipsilateral stroke, Black patients were more likely operated on within two weeks than White patients, with 48% vs. 42%, P = .004, respectively. However, timing of CEA (i.e. <2 weeks vs. ≥2 weeks) was more comparable among preprocedural ipsilateral TIA patients (44% vs. 39%, P = .07).
Perioperative details
Overall, regardless of symptom status, operation time was longer in Black patients, and although Black patients were less often discharged on acetylsalicylic acid (ASA), they were more often discharged on dual antiplatelet therapy (i.e. ASA and P2Y12-receptor antagonist, Table IB). Postoperative blood pressure control treated with IV medication was more common in Black patients.
Table IB.
Differences in patient characteristics between White and Black patients undergoing carotid endarterectomy, stratified on symptom status.
| Symptomatic patients | P-value | Asymptomatic patients | P-value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| (N = 17,115) | (N = 40,507) | |||||||||
| White | Black | White | Black | |||||||
| N | % | N | % | N | % | N | % | |||
| N | 16132 | 94 | 983 | 5.7 | 35581 | 95 | 1926 | 4.8 | ||
| Preprocedural angiogram | 654 | 4.1 | 33 | 3.4 | .3 | 1499 | 3.9 | 80 | 4.2 | .6 |
| General Anesthesia | 14882 | 92 | 906 | 92 | .9 | 35053 | 91 | 1780 | 92 | .02 |
| Eversion CEA | 1761 | 11 | 140 | 14 | .001 | 5103 | 13 | 279 | 15 | .1 |
| CEA without patch | 1756 | 11 | 136 | 14 | .005 | 3822 | 9.9 | 167 | 8.7 | .1 |
| Intraluminal shunt use | 9196 | 57 | 571 | 58 | .6 | 20766 | 54 | 1050 | 55 | .5 |
| Intraoperative EEG | 4724 | 29 | 290 | 30 | .9 | 9924 | 26 | 460 | 24 | .1 |
| Intraoperative stump pressure measurement | 1558 | 9.7 | 85 | 8.7 | .3 | 4107 | 11 | 258 | 14 | <.001 |
| Completion doppler | 9226 | 57 | 526 | 54 | .02 | 21153 | 55 | 1064 | 56 | .6 |
| Completion duplex | 3848 | 24 | 274 | 28 | .01 | 9017 | 23 | 556 | 29 | <.001 |
| Perioperative medication | ||||||||||
| Protamine | 10863 | 67 | 686 | 70 | .1 | 25695 | 67 | 1334 | 70 | .01 |
| Dextran | 1541 | 9.6 | 95 | 9.7 | .9 | 4187 | 11 | 222 | 12 | .4 |
| Hypertension treated with IV medication | 3047 | 19 | 291 | 30 | <.001 | 6419 | 17 | 545 | 28 | <.001 |
| Hypotension treated with IV medication | 1676 | 10 | 52 | 5.3 | <.001 | 3653 | 9.5 | 102 | 5.3 | <.001 |
| OP-Time Minutes (median, IQR)* | 112 (88–140) | 123 (96–15) | <.001 | 106 (83–135) | 114 (90–146) | <.001 | ||||
| Discharge medication | ||||||||||
| ASA | 14597 | 91 | 866 | 88 | .02 | 35091 | 91 | 1725 | 90 | .046 |
| P2Y12-antagonist | 6252 | 39 | 423 | 43 | .01 | 13465 | 35 | 781 | 41 | <.001 |
| Any antiplatelet | 15518 | 96 | 935 | 95 | .1 | 36895 | 96 | 1831 | 95 | .3 |
| Dual antiplatelet | 5331 | 33 | 354 | 36 | .1 | 11661 | 30 | 675 | 35 | <.001 |
| Statin | 14127 | 88 | 891 | 91 | .003 | 32612 | 85 | 1632 | 85 | .7 |
IQR: interquartile range, CEA: carotid endarterectomy, ASA: acetylsalicylic acid, EEG: electro encephalography,
>5% missing data.
In addition, among symptomatic patients, Black patients more often received an eversion type CEA and among those undergoing conventional CEA, Black patients were less likely to have patch closure (Table IB).
Outcomes on univariate analysis
Unadjusted rates of perioperative stroke/death (symptomatic (SX): 2.8% vs. 2.2%, P = .2; asymptomatic (ASX): 1.6% vs. 1.3%, P = .2, Table II), 30-day mortality (SX: 1.0% vs. 0.8%, P = .5; ASX: 0.7% vs. 0.6%, P = .6), and any in-hospital stroke (SX: 1.9% vs. 1.6%, P = .5; ASX: 1.0% vs. 0.8%, P = .3) were comparable between Black and White patients, as were rates of MI, CNI, and return to the operating room. However, compared to White patients, Black patients experienced higher rates of LOS >2 days (SX: 34% vs. 20%, P < .001; ASX: 22% vs. 12%, P < .001) and higher rates of failed discharge home (SX: 15% vs. 8.9%, P < .001; ASX: 6.3% vs. 2.7%, P < .001). Even after we excluded all patients with a recorded in-hospital complication in VQI (i.e. any stroke, MI, CNI, new dysrhythmia, new CHF, wound infection, reperfusion symptoms, and return to operating room), Black patients experienced higher rates of LOS >2 days and failed discharge home (all P < .001). For long-term survival analysis, 79% of patients were available after 1-year, with 56% after 2-years, and 34% after 3-years. Black and White patients experienced similar unadjusted long-term survival at 3-years, with 93% vs. 93%, P = .7, respectively.
Table II.
Differences in outcomes between White and Black patients undergoing carotid endarterectomy, stratified on symptom status.
| Symptomatic patients | P-value | Asymptomatic patients | P-value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| (N = 17,445) | (N = 41,238) | |||||||||
| White | Black | White | Black | |||||||
| N | % | N | % | N | % | N | % | |||
| N | 16132 | 94 | 983 | 5.7 | 35581 | 95 | 1926 | 4.8 | ||
| Perioperative any stroke/death | 361 | 2.2 | 28 | 2.8 | .2 | 496 | 1.3 | 31 | 1.6 | .2 |
| 30-day mortality | 127 | 0.8 | 10 | 1.0 | .5 | 220 | 0.6 | 13 | 0.7 | .6 |
| Any in-hospital stroke | 265 | 1.6 | 19 | 1.9 | .5 | 314 | 0.8 | 20 | 1.0 | .3 |
| Rankin scale score (median, IQR) | 3 (2–4) | 4 (2–5) | .3 | 3 (1–4) | 2 (0–4) | .2 | ||||
| Rankin scale score (mean, SD) | 3.0 | 1.7 | 3.5 | 1.6 | .3 | 2.7 | 1.8 | 2.1 | 1.9 | .2 |
| In-hospital MI | 143 | 0.9 | 5 | 0.5 | .3 | 274 | 0.7 | 16 | 0.8 | .6 |
| Any Cranial Nerve Injury | 495 | 3.2 | 26 | 2.8 | .5 | 975 | 2.7 | 42 | 2.3 | .3 |
| Any return to operating room | 319 | 2.0 | 24 | 2.4 | .4 | 653 | 1.7 | 43 | 2.2 | .1 |
| LOS (median days, IQR) | 1 (1–2) | 2 (1–3) | <.001 | 1 (1–2) | 1 (1–2) | <.001 | ||||
| LOS (mean days, SD) | 2.4 | 12.3 | 3.0 | 3.8 | <.001 | 1.8 | 7.2 | 2.8 | 12.3 | <.001 |
| LOS >2 days | 3149 | 20 | 329 | 34 | <.001 | 4517 | 12 | 428 | 22 | <.001 |
| Failed discharge home | 1438 | 8.9 | 151 | 15 | <.001 | 1040 | 2.7 | 121 | 6.3 | <.001 |
| Among patients without a recorded in-hospital complication* | ||||||||||
|
| ||||||||||
| N | 144775 | 94 | 898 | 5.7 | 35936 | 95 | 1775 | 4.7 | ||
| LOS > 2 days | 2352 | 16 | 264 | 29 | <.001 | 3192 | 8.9 | 328 | 19 | <.001 |
| Failed discharge home | 1130 | 7.6 | 120 | 13 | <.001 | 674 | 1.9 | 94 | 5.3 | <.001 |
IQR: interquartile range, MI: myocardial infarction, LOS: length of stay.
i.e. any recorded stroke, MI, CNI, new dysrhythmia, new CHF, wound infection, reperfusion symptoms, and/or return to operating room
Multilevel logistic regression for perioperative outcomes
After adjusting for: age, sex, insurance status, preprocedural ipsilateral stroke, timing of CEA after index neurological symptom, ambulatory status, IDDM, CAD, CHF, moderate anemia, end-stage renal failure, contralateral carotid occlusion (CCO), center and surgeon volume, preoperative angiogram, urgent procedure, general anesthesia, CEA type (i.e. conventional with vs. without patch vs. eversion), shunt use, IV dextran use, perioperative hypo-hypertension with IV medication, and discharge medication (i.e. ASA, statin), Black race was not associated with a higher risk of perioperative stroke/death (odds ratio (OR): 1.0 [95% C.I.: 0.8–1.3] P = .99, see Table III), 30-day mortality (OR: 0.9 [0.6–1.5] P =.7), any stroke (OR: 1.0 [0.7–1.4] P =.8), nor with MI, CNI, or any return to the operation room. Black race was associated with LOS >2 days (OR: 1.6 [1.4–1.8] P < .001) and failed discharge home (OR: 1.5 [1.3–1.8] P < .001).
Table III.
Association between race and outcomes after carotid endarterectomy, with White patients as referent.
| OR | 95% C.I. |
P-value | ||
|---|---|---|---|---|
| Perioperative any stroke/death | 1.0 | 0.8 | 1.3 | .99 |
| 30-day mortality | 0.9 | 0.6 | 1.5 | .7 |
| Any in-hospital stroke | 1.0 | 0.7 | 1.4 | .8 |
| In-hospital MI | 0.8 | 0.5 | 1.2 | .3 |
| CNI | 0.8 | 0.6 | 1.1 | .1 |
| Any return to operating room | 1.1 | 0.9 | 1.5 | .4 |
| LOS > 2 days | 1.6 | 1.4 | 1.8 | <.001 |
| Failed discharge home | 1.5 | 1.3 | 1.8 | <.001 |
MI: myocardial infarction, CNI: cranial nerve injury, LOS: length of stay.
Adjusted for: age, sex, insurance status, preprocedural ipsilateral stroke, timing of CEA after index neurological symptom, ambulatory status, insulin dependent diabetes mellitus (IDDM), coronary artery disease (CAD), congestive heart failure (CHF), anemia (Hb < 11g/dL), end stage renal failure, contralateral carotid occlusion (CCO), center and surgeon volume (divided into quintiles based on average annual volume), preoperative angiogram, elective vs. urgent procedure, general anesthesia, CEA type (i.e. conventional with vs. without patch vs. eversion), shunt use, IV dextran use, perioperative hypo- hypertension treated with IV medication, and discharge medication (i.e. ASA, statin).
Independent predictors of perioperative stroke/death
Table IV shows independent predictors of perioperative stroke/death and differences between Black and White patients in the associated risk of these factors. The most notable independent risk factors for perioperative stroke/death were: hypotension treated with IV medication (OR: 3.0 [2.6–3.6] P < .001), hypertension treated with IV medication (OR: 2.6 [2.3–3.1] P < .001), and CCO (OR: 1.8 [1.4–2.3] P < .001), whereas undergoing a procedure ≥2 weeks after index neurological symptom (OR: 0.8 [0.6–1.0] P = .03), an elective procedure (OR: 0.6 [0.5–0.7] P < .001) and being discharged on statin (OR: 0.6 [0.5–0.7] P < .001), or on ASA (OR: 0.4 [0.3–0.5] P < .001) were protective of perioperative stroke/death.
Table IV.
Independent predictors of perioperative stroke or death after carotid endarterectomy and interaction with race.
| OR | 95% | C.I. | P-value | Interaction P-value | |
|---|---|---|---|---|---|
| Hypotension treated with IV medication2 | 3.0 | 2.6 | 3.6 | <.001 | |
| No hypotension treated with IV medication | – Reference – | .01 | |||
| Hypotension treated with IV medication in black patients | 6.2 | 3.5 | 11.0 | <.001 | |
| Hypotension treated with IV medication in white patients | 2.6 | 2.3 | 3.0 | <.001 | |
| Hypertension treated with IV medication1 | 2.6 | 2.3 | 3.1 | <.001 | .5 |
| Contralateral carotid occlusion | 1.8 | 1.4 | 2.3 | <.001 | .5 |
| Preprocedural Angiogram | 1.5 | 1.1 | 2.0 | .004 | .3 |
| CEA without patch1 | 1.4 | 1.2 | 1.8 | .001 | .7 |
| Moderate anemia1 (Hb<11) | 1.4 | 1.2 | 1.7 | .001 | .5 |
| Insulin dependent diabetes mellitus1 | 1.4 | 1.1 | 1.7 | .001 | .8 |
| Intraluminal shunt use | 1.3 | 1.2 | 1.6 | <.001 | .9 |
| Preprocedural ipsilateral stroke1 | 1.3 | 1.1 | 1.7 | .006 | .7 |
| High volume cente2 (highest quintile) | 1.3 | 1.1 | 1.6 | <.001 | .2 |
| Dependent ambulatory status1 | 1.3 | 1.1 | 1.6 | .003 | .9 |
| Congestive heart failure1 | 1.2 | 1.0 | 1.5 | .04 | .9 |
| Coronary artery disease | 1.2 | 1.1 | 1.4 | .008 | .7 |
| Age ≥80 years2 | 1.2 | 1.0 | 1.4 | .02 | .3 |
| Timing of CEA after index neurological symptom (i.e. ≥2 weeks vs. <2 weeks) | 0.8 | 0.6 | 1.0 | .03 | .9 |
| Dextran IV use | 0.8 | 0.6 | 1.0 | .03 | .5 |
| General anesthesia | 0.7 | 0.6 | 1.0 | .02 | .7 |
| Elective vs. urgent procedure | 0.7 | 0.5 | 0.8 | <.001 | .6 |
| Discharged on statin | 0.6 | 0.5 | 0.7 | <.001 | .7 |
| Discharged on acetylsalicylic acid2 | 0.4 | 0.3 | 0.5 | <.001 | .8 |
More common in black patients,
More common in white patients
Only the associated risk of hypotension treated with IV medication differed significantly between Black and White patients (Black: OR: 6.2 [3.5–11.0] P < .001 vs. White: OR: 2.6 [2.3–3.0] P < .001, interaction P = .01). However, it is important to note that the prevalence of most risk factors associated with perioperative stroke/death was higher in Black patients than in White patients (Table IV).
Multivariable Cox regression for long-term survival
Black patients experienced significantly better long-term survival than White patients (hazard ratio (HR): 0.8 [0.7–0.9] P = .01, see Figure 1) after adjusting for age, sex, insurance status, preprocedural ipsilateral stroke, ambulatory status, smoking, IDDM, CAD, CHF, COPD, moderate anemia, GFR < 60 ml/min, CCO, prior non-cardiac bypass procedure, prior neck radiation, prior contralateral CEA, center and surgeon volume, CEA type (i.e. conventional with vs. without patch vs. eversion), perioperative hypo- hypertension treated with IV medication, and discharge medication (i.e. ASA, statin), including time-dependent covariates for: preprocedural ipsilateral stroke, perioperative hypo- hypertension treated with IV medication, age, and discharge medication (i.e. ASA, statin).
Figure 1.
Survival function derived from multivariable Cox regression model assessing long-term mortality in Black and White patients.
DISCUSSION
This study demonstrates that Black patients, regardless of symptom status, experience similar rates of perioperative stroke/death, 30-day mortality, in-hospital: stroke, MI, CNI, as well as unadjusted long-term survival after CEA as White patients, despite racial disparities in comorbidities, vascular risk factors, insurance status, hospital and surgeon volume, time to surgery after index neurological symptom, patch angioplasty and discharge medication. Moreover, after adjustment, which, in part, accounted for the identified racial disparities, Black patients experienced better long-term survival compared to White patients.
Several prior studies evaluated the impact of race on outcomes after CEA, but reported conflicting results, likely related to limitations of their data. Overall, most were limited by a small sample of Black patients, with very small event numbers.5,6,8,17,18 Additionally, those using administrative or Medicare data lacked information on preprocedural stroke or TIA laterality, impeding a reliable classification of symptomatic patients.5,7,9 This could result in biased racial comparisons among CEA patients, as Black patients are more likely symptomatic and more often have an ipsilateral stroke as their presenting symptom. Moreover, the three studies that used the ACS-NSQIP registry lacked detailed information on the degree of carotid artery stenosis, medication, hospital or surgeon volume, and insurance status.8,17,19 In addition, the non-targeted NSQIP may misclassify symptom status by including contralateral symptoms and those occurring more than six months prior to their procedure, impeding their overall analysis.20,21 However, more worrisome, they differed in their identified effect of race on outcomes after CEA, as two found no association between race and stroke or death,8,21 whereas one did find an association between Black race and 30-day mortality.18 Despite comparable perioperative complication rates between Black and White patients in our study, Black patients experienced longer LOS and more failed discharges to home, which might reflect differences in socioeconomic factors and social networks, in combination with their overall higher disease burden.
The higher prevalence of risk factors for perioperative stroke/death among Black patients, compared to White patients, illustrates the extent of racial disparities among CEA patients. The high prevalence of symptomatic patients among the Black population, of whom most have a stroke as their presenting symptom, might be related to their overall higher vascular disease burden, or to differences in antiplatelet medication, or a potential delay between diagnosis and intervention.3,4 Interestingly however, contrary to prior reports, we found that symptomatic Black patients more often underwent revascularization within two weeks of their index neurological symptom compared to symptomatic White patients. This could, in part, explain the comparable stroke rates in Black and White patients, despite the higher prevalence of vascular risk factors in Black patients, as delayed carotid revascularization has shown to increase the risk of preoperative stroke recurrence.22 Unfortunately, assessing preoperative stroke recurrence is not possible in VQI, since only the index neurological symptom is captured. On the other hand, a delayed CEA (i.e. ≥ 2 weeks vs. < 2 weeks) after the index neurological symptom resulted in a lower perioperative stroke/death risk, however at a likely cost of a higher risk of preoperative stroke recurrence. As any racial inequality in time to surgery among symptomatic CEA patients is unwarranted, this represents an opportunity for future quality improvement efforts.
In addition, some have suggested that Black patients might experience a different response to certain medical conditions, such as hypertension.23–25 This could explain the difference between Black and White patients in rates of postoperative hypo- and hypertension treated with IV medication, in addition to the higher associated risk of hypotension treated with IV medication in Black patients. However, it could also be related to less well-controlled preprocedural blood pressure among Black patients, unfortunately, information regarding preprocedural blood pressure is not captured by VQI. Regardless, we do recommend future research to focus on accurate blood pressure measurement and control in Black and White patients undergoing CEA to gain insight into racial differences in the hemodynamic response to carotid revascularization, as well as potentially reducing the associated risk.26 Moreover, among symptomatic patients, Black patients more often received CEA without patch closure than White patients. This observation is worrisome, as in prior research, patch angioplasty, compared to primary closure, decreased the risks of: perioperative death/stroke, long-term stroke, and restenosis.27,28 Hence, guidelines currently recommend patch angioplasty over primary closure for CEA patients. Efforts should be made to address these racial disparities in surgical care between Black and White CEA patients.
The better adjusted long-term survival for Black patients after CEA seems counterintuitive, however, since our multivariable Cox regression model adjusted for racial disparities such as, comorbidities, vascular risk factors, insurance status, hospital and surgeon volume, and surgical care, it, in part, diminished the impact of these racial disparities on outcomes after CEA and better reflects the impact of race, by itself, on outcomes after CEA. Moreover, prior work by our group, as well as two other studies, identified a similar adjusted survival benefit in Black patients undergoing vascular surgery for peripheral arterial disease (PAD).29–31 Similarly to Black PAD patients, Black patients undergoing CEA were younger and more likely female compared to White CEA patients, potentially explaining their overall better long-term survival. Although we accounted for these variables in our models, residual confounding likely remained.
Several limitations are inherent to this study and our results must be interpreted accordingly. First, we performed a retrospective analysis of prospectively collected data. This design does not obviate bias as a randomized trial would. However, we were able to partially account for this by our large sample size, which allowed for adjusted analysis. Second, the predefined variables captured by the VQI precluded additional detailed analysis based on socioeconomic factors, such as ZIP-codes, or on hospital type, as these were not captured. In addition, the de-identification of the data prevented any geographic analysis. Despite these limitations, we present a large contemporary cohort of CEA patients, which allowed adjusted analysis into the impact of race on both perioperative and long-term outcomes.
CONCLUSION
Despite widespread racial disparities in comorbidities, vascular risk factors, insurance status, hospital and surgeon quality, time to surgery after index neurological symptom, patch angioplasty and discharge medication among patients undergoing CEA, rates of perioperative stroke or death, as well as unadjusted long-term survival were comparable between Black and White patients. Moreover, after adjustment, which, in part, accounted for the identified disparities in vascular risk factors and surgical care, Black patients experienced better long-term survival compared to White patients. Further research should be directed at understanding the underpinnings of these racial inequities.
Take Home Message
Analysis of 57,622 carotid endarterectomies revealed that black patients (n=2,909), despite having a greater prevalence of risk factors, experienced similar rates of perioperative stroke/death and unadjusted survival, than white patients (n=54,713). Black patients had better adjusted long-term survival.
Recommendation
This study suggests that black patients can expect similar results than white patients following CEA, despite more vascular risk factors.
Acknowledgments
PS, TO, and SD are supported by the Harvard-Longwood Research Training in Vascular Surgery NIH T32 Grant 5T32HL007734-22
Footnotes
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
This manuscript was presented as an oral presentation at the 2017 SVS Vascular Annual Meeting, San Diego, CA
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