The authors of this studied identified a population at elevated risk for endarterectomy that were socio-economically similar and receiving care without charge within the Veterans Affairs health care system. Therefore, they “expected [this] homogenous cohort of patients [to] be reasonable candidates for carotid endarterectomy.” The study included all veterans over 45 years of age discharged from any VA hospital from October 1, 1988 to September 30, 1989 with a diagnosis of ischemic stroke or transient ischemic attack (TIA). Socioeconomic status was controlled by limiting the cohort to veterans within a selected income category (ie. 1990 annual income <$17,240), given that “patients in this category are unlikely to have additional health care coverage and, therefore, they are less likely to receive supplemental care outside the VA health care system.”

“Even after adjusting for socioeconomic status in [a] more rigorous manner,” the investigators found that “black patients received carotid angiography at less than half the rate of white patients” and Hispanics “at a rate 20% below white patients.” Race was “a strong predictor of receiving carotid endarterectomy.” After adjustment for several confounding variables, “black patients were one third as likely as white patients to receive carotid endarterectomy,” and “Hispanics were less than half as likely as white patients to subsequently receive” the procedure.

The authors suggest that “differences in clinical features of ischemic stroke that reduce the rate of endarterectomy for black and Hispanic patients” could explain the racial disparities in selected treatments. However, research supporting this hypothesis is discordant. A second possible explanation is that “black and Hispanic patients may have different symptom patterns for cerebrovascular disease that result in less frequent referral for further diagnostic workup which would uncover carotid lesions that may be amenable to endarterectomy.” According to the authors, “the findings are even more likely to be explained by the high prevalence of severe hypertension in black patients.” However, in this study there was “no evidence for an interaction between hypertension and black race for patients referred for angiography, implying that black and white patients with hypertension received angiography at similar rates.” Yet, “a third explanation for the observed difference is a race-related bias in referral of hospitalized patients for further diagnostic workup for potential endarterectomy. This bias may arise from an implicit belief among clinicians that black patients are unlikely to have significant extracranial disease and, thereby, carotid imaging is unwarranted.” Such a justification was weakened by the finding that although “patients with higher comorbidity scores were less likely to be referred for these procedures, there was no difference in the distribution of comorbidity scores between racial groups.”