Aphasia severity is modulated by race and lesion size in chronic survivors: A retrospective study.

INTRODUCTION: In stroke survivors with aphasia (SWA), differences in behavioral language performance have been observed between Black and White Americans. These racial differences in aphasia outcomes may reflect biological stroke severity, disparities in access to care, potential assessment bias, or interactions between these factors and race. Understanding the origin of disparities in aphasia outcomes is critical to any efforts to promote health equity among SWA. In this study, we explore aphasia outcomes by examining the relationship between race, socioeconomic status, and neurological factors in SWA. METHOD: Eighty-five chronic left-hemisphere SWA (31 Black, 54 White) participated in the study. The primary aphasia outcome measure was the Western Aphasia Battery-Revised (WAB-R). Lesion size was measured based on manual lesion segmentations. FLAIR and T2 images were scored for severity of white matter disease. Independent sample t-tests were used to determine differences by race in education, age, income, aphasia severity, white matter disease, and lesion size. A linear regression model was used to explore factors that predicted aphasia severity on the WAB-R. RESULT: Level of education and estimated income differed by race in our sample. For predictors of aphasia severity, the regression model revealed a significant effect of lesion size on WAB Aphasia Quotient and an interaction of race x lesion size, such that Black and White participants with small lesions had similar WAB scores, but in individuals with larger lesions, Black participants had lower WAB scores than White participants. CONCLUSION: We suggest two explanations for the difference between Black and White SWA in the relationship between lesion size and aphasia severity. First, the impact of disparities in access to rehabilitation after stroke may be more evident when a stroke is larger and causes significant aphasia. Additionally, an assessment bias in aphasia outcome measures may be more evident with increasing severity of aphasia. Future studies should further discern the drivers of observed disparities in aphasia outcomes in order to identify opportunities to improve equity in aphasia care.