Abstract 302: Incidence of moyamoya angiopathy in the United States from 2011‐2020

Introduction Moyamoya angiopathy (MMA) is a rare cerebrovascular condition characterized by progressive steno‐occlusion of the terminal segments of the internal carotid artery (ICA) and its branches. Contemporary population‐based studies evaluating the incidence of MMA in the United States (US) are lacking. Materials/Methods We utilized the State Ambulatory Surgery, Emergency and Inpatient Databases of Florida (2005‐2020), Georgia (2010‐2020), Maryland (2012‐2020) and New York (2005‐2020) to conduct a retrospective study. We validated International Classification of Diseases (ICD) Tenth revision codes for MMA in a single academic center in the US and utilized primary and secondary ICD‐Ninth/Tenth revision discharge codes to identify all new cases of MMA in these four states from 2011‐2020. Results From 24,614 MMA hospitalizations over the study period, 4,192 incident cases were identified from 2011‐2020. 67.9% of these admissions were in women. The overall crude incidence of MMA was 0.76 (95%CI 0.74‐0.78) cases/100,000/year. Incidence was higher in Asian (aIRR 2.46, 95%CI 1.88‐3.23)) and Black individuals (aIRR 2.58, 95%CI 2.17‐3.07) compared with Non‐Hispanic White individuals. Incidence increased by 8% annually over time (aIRR 1.08, 95%CI 1.03‐1.02) with most of this increase occurring in individuals 45‐64 years and ≥65 years. Conclusion The incidence of MMA in the US over the period 2011‐2020 was 0.76/100,000/year but incidence of detected cases increased over time. Overall incidence in Black individuals is just as high as that of Asian individuals, and both are higher than that of Non‐Hispanic White individuals.