Racial Disparities in Time to Huntington Disease Diagnosis in North America: An ENROLL-HD Analysis

Abstract

Background and objectives: There are well-documented racial and ethnic disparities in access to neurologic care and disease-specific outcomes. Although contemporary clinical and neurogenetic understanding of Huntington disease (HD) is thanks to a decades-long study of a Venezuelan cohort, there are a limited number of studies that have evaluated racial and ethnic disparities in HD. The goal of this study was to evaluate disparities in time from symptom onset to time of diagnosis of HD.

Methods: Using the ENROLL-HD periodic data set 5 (PDS5), we performed sequential multivariate linear regressions to evaluate sociodemographic factors associated with disparities in time to diagnosis (TTD) for gene-positive individuals (CAG repeats 36+) in the North America region. Sensitivity analyses included imputed multivariate regression analysis of individuals with a total motor score (TMS) of 10 or higher and those with 40+ CAG repeats. We also used descriptive statistics to present TTD data in other ENROLL-HD participating regions.

Results: Among 4717 gene-positive participants in the North American region, 89.5% identified as White, 3.4% as Hispanic or Latino, and 2.3% as African American/Black. The average TTD in the group was 3.78. When adjusting for clinical and sociodemographic variables, Black participants were diagnosed with HD 1 year later than White participants (p < 0.05). Additional factors associated with a later diagnosis included psychiatric symptoms as initial HD symptom, unemployment during baseline ENROLL visit, and higher educational attainment. Sensitivity analysis of gene-positive (36+ CAG) participants with a TMS of 10 or higher and of those with 40+ CAG repeats yielded similar findings.

Discussion: Across multiple statistical models, Black ENROLL-HD participants were diagnosed with HD 1 year later than White participants. Clinical factors suggesting a delay in HD diagnosis included psychiatric symptoms at disease onset and a negative family history of HD. Unemployment during baseline visit and higher educational attainment were sociodemographic factors suggestive of a later diagnosis. Additional multicenter qualitative and quantitative studies are needed to better understand reasons for delays in HD diagnosis among Black individuals, and the role of social and structural determinants of health in obtaining a timely HD diagnosis.

Figure 1. Participant Selection for Study Analysis

Figure 2. Conceptual Model of the Relationship Between Race/Ethnicity and Time-to-Diagnosis in Individuals With Huntington Disease

*Of these variables, ENROLL-HD only has data on level of education, employment status during each visit, and individuals' geographic location (ex: urban vs rural).

Figure 3. Participant Characteristics and Time-to-Diagnosis in Latin America, Europe, and Australasia