Demographic, imaging and disease patterns of moyamoya angiopathy in South Auckland: an observational study from electronic health records.

Background: Prior reports show the occurrence of moyamoya angiopathy in the ethnically diverse South Auckland region, but little is known about the sociodemographic burden of the condition and clinical outcomes.

Aims: To determine the disease prevalence, age, sex and ethnic distribution, management and patient outcomes in adults residing in South Auckland (population 567 000). We also sought to determine associations with the outcomes of vascular events and functional independence following diagnosis.

Methods: We searched hospital medical records and radiology reports dating from 2008 to 2024 for the region using relevant ICD codes and the word 'moyamoya'. We used descriptive statistics and local population data to calculate point prevalence as of 19 September 2024. Statistical tests of association were performed for continuous, categorical and time-to-event data for the prespecified outcomes.

Results: We identified 49 patients with a total of 300 patient-years of follow-up. The point prevalence ranged from 4/100 000 in NZ Europeans and Asian people to 10/100 000 in Māori and 14/100 000 in Pacific Islanders. The mean age at diagnosis was 37 (standard deviation 16) years and females outnumbered males by 3:1. One-quarter had a vascular event within a median of 457 days from diagnosis and two-thirds of the overall cohort were independent on follow-up. Factors associated with a loss of independence included stroke/transient ischaemic attack (TIA) during follow-up, bilateral disease and severe hypoperfusion on imaging. The mortality rate was 14%.

Conclusions: In this New Zealand-based study, we found a wide ethnic variation in the prevalence of moyamoya angiopathy and an elevated early risk of TIA and stroke following diagnosis.