E093 The effect of new classification criteria on the diagnosis of large vessel vasculitis

Abstract

Abstract Background/Aims Giant cell arteritis and Takayasu arteritis are the two recognised forms of large vessel vasculitis. Clinically there is recognition of large vessel vasculitides which are not easily classified into the two forms. Classification criteria have been proposed since 1990 and have been updated in 2022. Classification criteria should be able to minimise the number of cases that are unclassifiable, and the number of cases that are classified into more than one set. We test both sets of criteria to test their performance in our cohort. Methods In our centre, between January 2011 to December 2020, 270 individuals were diagnosed as having large vessel vasculitis by virtue of having either a positive biopsy, ultrasonography, or positron emission tomography. The 1990 and the 2022 classification criteria were applied to our cohort. Results The mean age was 74. 181 were female. The results are as in Table 1. Using the 1990 criteria, 2 individuals met both classifications and 30 did not meet either. Using the 2022 criteria, 3 individuals met both classifications and 24 did not meet either. The numbers classified as having Takayasu arteritis has reduced from 13/270 to 2/270. The numbers classified as giant cell arteritis have increased from 225/270 to 241/270. Conclusion The new classification criteria have expanded the phenotype recognised as giant cell arteritis by mainly including previously unclassified individuals, and narrowed the phenotype recognised as Takayasu mostly by declassifying it as not meeting any criteria. Overall, the new criteria improve classification for 5/270 (1.8%) cases. Disclosure C.B. Mukhtyar: None. C. Beadsmoore: None. F. Coath: None. G. Ducker: None. K. Sisson: None. R.A. Watts: None.