FRI0223 SUBPHENOTYPES OF ANCA ASSOCIATED VASCULITIS IDENTIFIED BY LATENT CLASS ANALYSIS

Background: ANCA associated vasculitides (AAV) are a heterogeneous group of rare diseases with unknown etiology and the clinical spectrum ranging from life-threatening systemic disease, through single organ involvement to minor isolated skin changes. Thus there is an unmet need for phenotype identification especially among patients with granulomatosis with polyangiitis GPA, patients with microscopic polyangiitis MPA group seems to be more uniform. Recently, based on previous clustering analysis and clinical, histopathological, serological and prognostic aspects three subcategories of AAV have been proposed and named as: non-severe AAV, severe PR3-AAV and severe MPO-AAV [1]. Objectives: In line with these attempts to subcategorize AAV we decided to use latent class analysis (LCA) on a large multicenter cohort of polish AAV patients from POLVAS [2] registry to identify potential new subphenotypes or confirm already proposed ones. Methods: Latent Class Analysis (LCA) approach was used as a model based clustering method of objects described by dichotomous (e.g., gender; ANCA status – cANCA, pANCA; organ involvement - skin, eye, ENT, respiratory, heart, GI, renal, urinary, CNS, peripheral nerves) and polytomous (number of relapses) variables supported by quantitative covariates (e.g., age at diagnosis, CRP at diagnosis, maximal serum creatinine concentration ever). Results: Results of LCA on our AAV group returned four class model of AAV subphenotypes, confirming existence of the previously proposed by Mahr at al. [1] and revealed fourth – previously not described clinically relevant subphenotype. To this fourth class - belong patients only with GPA, diagnosed at young age, with multiorgan involvement, high relapse rate and relatively high risk of death. Conclusion: Based on multiple clinical and serological variables LCA methodology identified 4-class subphenotypes model of AAV. Fourth-class is a new clinically important subphenotype including exclusively PR3-positive young AAV patients with multiorgan involvement, high risk of relapse and distinct mortality. References: [1]Mahr A, Specks U, Jayne D. Subclassifying ANCA-associated vasculitis: a unifying view of disease spectrum. Rheumatol Oxf Engl 2019;58:1707–9. https://doi.org/10.1093/rheumatology/kez148. [2]Wojcik K, Wawrzycka-Adamczyk K, Wludarczyk A, Sznajd J, Zdrojewski Z, Masiak A, i in. Clinical characteristics of Polish patients with ANCA-associated vasculitides—retrospective analysis of POLVAS registry. Clinical Rheumatology. 1 wrzesien 2019;38(9):2553–63. Disclosure of Interests: Krzysztof Wojcik: None declared, Adam Cmiel: None declared, Anna Masiak: None declared, Zbigniew Zdrojewski: None declared, Radoslaw Jeleniewicz: None declared, Maria Majdan Consultant of: Roche, Amgen, Speakers bureau: Roche, Amgen, Iwona Brzosko: None declared, Marek Brzosko: None declared, Piotr Gluszko: None declared, Malgorzata Stasiek: None declared, Malgorzata Wislowska: None declared, Joanna Kur-Zalewska: None declared, Marta Madej: None declared, Anna Hawrot-Kawecka: None declared, Hanna Storoniak: None declared, Barbara Bullo-Piontecka: None declared, Alicja Debska-Ślizien: None declared, Eugeniusz Kucharz: None declared, Katarzyna Jakuszko: None declared, Jacek Musial: None declared