Abstract Background Eosinophilic granulomatosis with polyangiitis (EGPA) exhibits geographic heterogeneity in demographics and organ involvement. Japan has been reported to show relatively higher rates of peripheral neuropathy and female predominance compared with some Western cohorts. The Hokuriku district (Ishikawa, Fukui, Toyama) had a combined population of 2,854,632 in 2023, providing a useful regional context for describing EGPA characteristics. Methods We conducted a retrospective analysis of a multi-center hospital-based dataset from the Hokuriku district. Variables included demographics, classification category (Definite/Probable), peripheral blood eosinophil counts, MPO-ANCA results, complications/organ involvement (free-text multi-select), and physician-rated disease severity grades. Descriptive statistics are presented as median IQR or % of available data; no incidence or prevalence was inferred from this convenience cohort. Results Among 26 records, age data were available in 26: median 66 years 42.5-72.0, range 22-86. Female sex comprised 65.4% and male 34.6% (remainder unspecified). Classification was Definite in 24 and Probable in 2.Peripheral blood eosinophils (n = 25) showed a median of 10,950/µL 4,350-13,090. MPO-ANCA was measured in 24 and positive in 5 (20.8%) based on site-reported values (heuristic threshold applied to numeric entries; values explicitly marked “negative” or “10” treated as negative).From complication/organ-involvement entries, the most frequent features were: Sinonasal involvement (including sinusitis/nasal polyps/allergic rhinitis): 17/26 (65.4%), Pulmonary infiltrates (radiographic): 9/26 (34.6%), Peripheral neuropathy (including mononeuritis multiplex descriptors): 12/26 (46.2%), Cutaneous purpura: 3/26 (11.5%)Disease severity grade was recorded in 26: Grade 2 in 20/26 (76.9%), Grade 1 in 4/26 (15.4%), and Grade 4 in 1/26 (3.8%); one additional note indicated death due to cirrhosis while EGPA was treated with prednisolone. Conclusions This Hokuriku hospital-based cohort shows a female-leaning, older-adult EGPA population, marked eosinophilia, and frequent sinonasal disease with a substantial proportion exhibiting peripheral neuropathy, aligning with patterns described from Japan overall. MPO-ANCA positivity was present in about one-fifth of tested cases. While these findings cannot be generalized to population incidence, the 2023 regional population (∼2.85 million) contextualizes the clinical burden within a defined Japanese district. Prospective, population-based surveillance across Hokuriku centers is warranted to validate these signals, refine serologic cut-points, and examine outcomes with contemporary therapies. This abstract is funded by: none
Waseda et al. (Fri,) studied this question.