Background/Purpose: There are few data on clinical profiles of ANCA-associated vasculitis (AAV) and or ANCA specificity in different ethnic populations. This study examined differences in the clinical features of AAV between populations using the Diagnostic and Classification Criteria in Vasculitis Study (DCVAS) dataset.  

Methods: DCVAS is an international, multi-center observational study recruiting in 128 sites worldwide. Rheumatology, renal, immunology, neurology, respiratory and dermatology specialties contributed to recruitment. Ethnic groups were categorized into 8 groups: Chinese, Northern & Southern European, Indian subcontinent, Japanese, Middle Eastern, White American. Other ethnic groups of <50 people were excluded. ANCA type was categorized as MPO, PR3, and ANCA-negative. The extent of organ involvement was classified by the presence of constitutional, musculoskeletal, skin, ophthalmic, ENT, respiratory, cardiovascular, gastroenterological, genitourinary, and neurological symptoms. Differences were analyzed by chi-squared test using a Bonferroni correction, and logistic regression (adjusting for age, sex, specialty of recruiting center). Northern European was the reference group.  

Results: Data from 1,069 patients were included (Table 1). Recruiting specialties were not evenly distributed among ethnic groups. There were differences in ANCA type between ethnic categories (p<0.001). MPO was more common than PR3 in Southern European, Chinese, & Japanese; and PR3 was more common in the other ethnic categories. ANCA-negative AAV was more common in White Americans than in Northern Europeans. These effects remained after adjustment for age, sex, and recruiting specialty. There were differences in organ involvement in the crude analysis: systemic involvement was less common in Southern Europeans, renal involvement more common in Chinese and Japanese, musculoskeletal less common in Southern European, Chinese and Japanese, ophthalmic more common in Indian and less common in Japanese. Adjustment for age and sex did not alter the associations. However, recruiting specialty confounded the association between ethnicity and system involvement for all organ systems. Due to interaction, the analysis was stratified by recruiting specialty. The majority (83.7%) of patients were recruited by rheumatology. Within this group, there were no significant differences, except ophthalmic and ENT involvement were less common in Japanese people compared to Northern Europeans. The numbers in the other specialties were too small to draw conclusions.  

Conclusion: This study confirms the previously-observed differential occurrence of MPO-AAV and PR3-AAV. Organ system involvement in AAV does not appear to be different among various ethnic groups, after accounting for the different likelihood of seeing and recording symptoms in different specialties.