Disparities in Huntington Disease Severity: Analysis Using the ENROLL-HD Dataset

Abstract

Background and objectives: Social and structural determinants of health (SDOH) have been associated with disability in neurologic diseases. However, the association between these factors and disability in Huntington disease (HD) has not been studied. This study aimed to evaluate the association of racial and sociodemographic factors with disease severity in patients with HD in North America.

Methods: We conducted a cross-sectional study of genetically confirmed participants with HD (36+ CAG repeats) in the North American region using the ENROLL-HD 2020 periodic dataset. In this analysis, our exposure variable was the participant's race/ethnicity. The main outcome measure was disease severity, as measured by the Total Functional Capacity Score (TFC), which measures the level of disability of patients with HD. We used multivariate regression models to adjust for sociodemographic factors that may mediate or moderate a causal effect between race/ethnicity and disease severity.

Results: Among 4,717 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 TFC score was 10.22 (SD 3.22); 48% of participants completed either secondary education (including college) or a professional degree, and 55% lived in a city and not in a town, village, or rural location. In multivariate regression models, we found that Black participants and those with less than a high school degree entered the ENROLL-HD study with lower TFC scores than White participants. We also found that compared with those with at least a high school degree, those who completed some form of higher education or professional degree had higher TFC scores (p < 0.001). This multivariate analysis did not find an association between geographic location and TFC score.

Discussion: Our study found that Black participants in North America presented to ENROLL-HD with more advanced disease than White patients. We also found that higher education was associated with less advanced disease when entering the ENROLL-HD study. The role of race/ethnicity and education in HD symptom severity warrants further investigation. These findings underscore the importance of further studying the role of social and structural determinants of health in patients with HD, particularly those from historically marginalized communities.

Figure 1. Participant Selection for Analysis

*ENROLL-HD aggregates data for individuals with 70 CAG repeats or more.

Figure 2. Conceptual Model of the Relationship Between Race/Ethnicity and Disease-Specific Outcomes in Huntington Disease

Moderators: Biological variables including age, sex, CAG repeat length, and the type of symptom at disease onset. Mediators: Social and structural determinants of health, including level of education, employment status, insurance, income, and geographic location.