Rising Incidence of Moyamoya Angiopathy in the United States

The incidence of moyamoya angiopathy (MMA) is rising in the United States, with disparities among racial groups. These findings were published in Neurology.

Researchers conducted a retrospective study using data from Florida (2005-2020), Georgia (2010-2020), Maryland (2012-2020), and New York (2005-2020) to estimate the incidence of MMA and analyze trends over time. Patients with MMA were classified as having moyamoya syndrome (MMS) if they had 1 or more comorbid vasculopathy risk factors. Moyamoya disease (MMD) was defined as MMA without these risk factors. Joinpoint and Poisson regression models were employed for statistical analysis.

A total of 19,468 hospital encounters for MMA from the 4 study states were included, of which 21.5% were identified as incident visits. In this cohort of incident visits, the median age at MMA diagnosis was 41 (IQR, 24.0-54.0) years, 67.9% were women, and 25.4% had MMS. Cases of MMS had a disproportionate distribution across racial and ethnic groups, with 44.5% being non-Hispanic Black, 12.4% being non-Hispanic White, and 8.3% being Asian. The most common comorbid vasculopathy was sickle cell disease, which was present in 62.4% of total MMS cases and 84.7% of MMS cases in non-Hispanic Black individuals.

Overall, the age- and sex-standardized incidence of MMA per 100,000 population was 0.75 (95% CI, 0.73-0.77), the incidence of isolated MMD was 0.57 (95% CI, 0.54-0.59), and the incidence of MMS was 0.18 (95% CI, 0.16-0.20). Incidence of MMD increased with age up to 65 years (P =.041), whereas incidence of MMS declined with age (P <.001). Incidence of MMA was higher among women than men (adjusted incidence rate ratio [aIRR], 1.97; 95% CI, 1.69-2.30).

Incidence of MMA was higher among Black individuals (aIRR, 2.58; 95% CI, 2.17–3.07) and Asian individuals (aIRR, 2.46; 95% CI, 1.88–3.23) compared with non-Hispanic White individuals, but lower among Hispanic individuals (aIRR, 0.80; 95% CI, 0.68–0.94).

The age- and sex-standardized incidence of MMA increased over time, with a 7.7% annualized percentage change (95% CI, 5.3%-10.5%). The pace of the increase was faster in Black and Asian individuals when compared with White individuals.

Study limitations include the use of diagnostic codes and a likely underestimation of true incidence.

“Further studies are needed to understand the genetic and environmental factors contributing to race/ethnic disparities in MMA incidence in the United States,” the authors wrote.