Evaluation of a new algorithm in classification of systemic vasculitis

Objective. Recently, a new consensus algorithm for classification of ANCA-associated vasculitis (AAV) and PAN had been proposed by Watt et al. for epidemiological studies. In order to evaluate this algorithm, the current study used the algorithm to reclassify the patients with AAV and PAN in our centre. Methods. Five hundred and fifty Chinese patients with primary systemic vasculitis diagnosed in our referral diagnostic centre during the past 10 years were retrospectively studied. Four hundred and ninety-three out of 550 were ANCA positive. We compared the new consensus algorithm and the 1994 Chapel Hill Consensus Conference (CHCC) definitions supplemented with surrogate parameters, in the same cohort of patients with primary systemic vasculitis. Results. Applying the CHCC definitions with surrogate parameters, the diagnoses were ChurgStrauss syndrome (CSS) (n=0), WG (n=127), microscopic polyangiitis (MPA) (n=363), PAN (n=4) and unclassified (n=56). Using the new consensus algorithm, the diagnoses were CSS (n=2), WG (n=199), MPA (n=329), PAN (n=0) and unclassified (n=20). Conclusions. Watts algorithm was a useful method to classify patients into a single category, with less unclassified patients and without overlapping diagnosis, which allows their use in epidemiological studies.