Abstract Body: Introduction
Hereditary Hemorrhagic Telangiectasia (HHT) is a rare vascular disease characterized by development of arteriovenous malformations (AVMs) throughout the body, including telangiectases on the skin, nasal and gastrointestinal mucosal surfaces and larger AVMs in the brain, lungs, and liver. AVMs can rupture causing life-threatening hemorrhage, stroke, and heart failure, thus requiring referral and management of care at specialized HHT centers. Disparities at the individual and neighborhood levels may contribute to delays in treatment and poorer health outcomes. We aimed to explore associations between neighborhood socioeconomic status (SES) and health outcomes of HHT patients.

Methods
This is a retrospective cohort study of HHT patients enrolled in the Brain Vascular Malformation Consortium study at UC San Francisco between 2011-2024. Among 187 enrolled, 169 had valid addresses in California. The University of Wisconsin’s Neighborhood Atlas® mapping tool was used to find the State Area of Deprivation Index (ADI) of each patient’s address. The ADI uses SES data from the U.S. Census (e.g., education, income/employment, housing, and housing characteristics), but does not use race to rank the social disadvantage of geographic areas. Outcomes included age at genetic testing, HHT Severity Score (0-7 composite score factoring in AVM, anemia and stroke), and Epistaxis Severity Score (ESS) (0-10 composite score of nosebleed severity over last 3 months). Multivariable linear regression analysis test the association between ADI and health outcomes, adjusting for age and sex; statistical significance was set at p≤0.05.

Results
The mean age of the cohort at enrollment was 41±21 years and 65% were female. Median HHT Severity Score was 2 (range: 0-6) and mean ESS was 3.2±2.2. Mean age at genetic testing was 36±20 years. The distribution of ADI was roughly uniform, ranging from 1 (least disadvantaged) to 10 (most disadvantaged). No significant association was observed between ADI and HHT Severity Score (n=150, beta=0.048, 95% CI: -0.19 to 0.114, p=0.157), ESS (n=150; beta=0.012, 95% CI: -0.100 to 0.125, p=0.829), or age at genetic testing (n=109; beta= -0.732, 95% CI: -2.07 to 0.604, p=0.279).

Conclusions
There was no clear evidence for disparities in health outcomes of HHT patients based on their neighborhood SES within California despite a wide range of ADI values, suggesting that individual-level characteristics may play a greater role.