The authors sought to determine whether there are racial differences in use of carotid artery imaging after controlling for clinical factors and to ascertain racial differences in presenting signs and symptoms and appropriateness for carotid endarterectomy (CE). Although black patients are known to be at higher risk for ischemic stroke, they are only one-third to one-fourth as likely to receive carotid endartercectomy. “Physicians may refer black patients for imaging studies at a lower rate because fewer black patients have clinical signs and symptoms that suggest high-grade lesions in the anterior carotid distribution.” Thus, this study examined the interaction between signs and symptoms as a potential mediator in explaining the racial difference in the proportion of patients who receive carotid artery imaging to define their appropriateness for CE. For those patients who received such diagnostic imaging, the authors determined whether there was a racial difference in the use of CE after accounting for differences in clinical status. The study sample was drawn (by random sampling for whites and modified random sampling for blacks) from all patients discharged from any of four Veterans Affairs hospitals with diagnoses of either transient ischemic attack (TIA), ischemic stroke, or amaurosis fugax.

Information on the clinical presentation of the 803 subjects was collected from medical records and classified using a modified version of the RAND criteria to determine the primary condition as stroke or TIA. RAND/AMCC guidelines were also employed to assess the appropriateness of carotid endarterectomy. Data on possible confounders – such as comorbid conditions, degree of carotid artery stenosis, and degree of “operative risk” for CE – were collected.

With respect to carotid artery imaging, the results indicated that “fewer black than white patients with TIA received noninvasive or invasive studies of their carotid arteries during their index admission or in the 6 months after the admission (83% versus 94.0%, respectively; P=0.003). This pattern held for any use of carotid Doppler/duplex scanning (76% of blacks versus 89% of whites; P<0.001) irrespective of use of carotid angiography and for any use of carotid angiography irrespective of use of noninvasive imaging (27% versus 49%; P,0.01)…Among patients with vertebrobasilar TIAs, 44% (4/9) of blacks but 70.6% (12/17) of whites received carotid artery imaging (P=0.20); the lack of statistical significance is a likely consequence of the small number of patients involved.” For both black and white patients, the “overall constellation of signs and symptoms nor any specific symptom (with 1 exception) was associated with having carotid artery imaging. The 1 exception was presence of sensory or motor deficits of the arms, which, among whites only, was associated with a greater likelihood of receiving imaging of the carotid arteries (P<0.01).” After adjusting for clinical variables, other then presenting symptoms or signs, “white patients were approximately 50% more likely to receive imaging than were black patients.”

Overall, the results from the carotid artery imaging indicated a low prevalence of high grade stenosis among patients. However, “in terms of arterial stenosis in the portion of the internal carotid artery distal to that considered for potential CE, 7% of blacks and 6% of whites had high grade stenosis (ie, >70%) in the cervical or petrous arteries, and 4% of blacks and 4% of whites had stenosis of >70%.” According to classification by the RAND criteria, “more whites than blacks were considered either appropriate (18% versus 4%, respectively), or uncertain (22% versus 15%, respectively) candidates for CE.”

Nonetheless, of these patients classified as appropriate for CE, 38 of 57 white patients (67%) underwent CE, whereas 5 of the 10 black patients (50%) classified as appropriate underwent the procedure. “The relative risk of CE for whites compared with blacks was 1.34 (95% CI, 0.70 to 2.53).” Furthermore, “of the 72 whites classified as uncertain, 17 (24%) received CE, compared with 1 of the 39 blacks (3%) classified as uncertain (relative risk, 9.2; 95% CI, 1.26 to 66.7). Finally, 1 of 196 whites classified as inappropriate received a CE compared with none of the 210 blacks in this category.” When the investigators examined the symptoms and clinical characteristics of the patients who did not receive CE but were classified as appropriate for CE according to the RAND/AMCC criteria, they found that “there was no discernible pattern in the accompanying symptoms or other clinical factors that might explain the choice to not use CE for these patients compared with white patients who did not receive the procedure.” Three potential explanations are offered for this finding. First, “financial barriers to care for invasive procedures” may exist; however, patients in this study received care in a VA hospital—an equal access healthcare system. Second, “there may be a racial difference in the quality of the patient-physician communication about the disease process and treatment options that lead to differences in patients’ understanding of their options.” Third, “there may be a racial difference in patient preferences for a given treatment option, leading to a lower rate of surgical treatment among blacks.”

The authors conclude, “further effort should be focused on potential racial differences in the evaluation and treatment of cerebrovascular disease before hospitalization, with emphasis on the physician-patient interaction surrounding decision making for the procedure, and the determinants of physician recommendations. This information will be essential for designing intervention strategies to ensure that there is equal access to effective therapies while patient autonomy is respected.”

This study yielded several important findings in the debate about the cause of racial disparities in the use of invasive and noninvasive care for cerebrovascular disease. First, the hypothesis that racial differences in care may be explained by differences in presenting symptoms or other clinical variables (as measured in this study) was not substantiated. Differences in treatment persisted after adjusting for these possible confounders. Secondly, the findings of this study disagree with previous claims that racial differences in care were largely due to differences in the extent of arterial stenosis in the intracranial portion of the carotid arteries. In fact, 7% of blacks and 6% of whites had high-grade stenosis in the internal carotid artery, which is considered to indicate CE as necessary. Third, blacks were not only less likely to undergo CE, they were also significantly less likely to undergo carotid artery imaging, a necessary diagnostic procedure to determine appropriateness for CE. Fourth, even among those patients classified as appropriate for surgery—using RAND/AMCC criteria—blacks remained significantly less likely to undergo CE. Furthermore, the investigators noted that the “racial difference in use of CE was most pronounced in the category of patients for whom the procedure was deemed of uncertain appropriateness according to RAND/AMCC guidelines,” thus implying “greater room for discretion for physicians in presenting management options.”