Objectives: To evaluate the use of the diagnostic criteria for Wegener's granulomatosis (WG) and microscopic polyangiitis (mPA) proposed by Sørensen et al. in the classification of primary systemic vasculitis (PSV).
Methods: We applied to our cohort of PSV patients the American College of Rheumatology (ACR) criteria for WG, Churg-Strauss syndrome (CSS) and polyarteritis nodosa (PAN), the Chapel Hill Consensus Conference (CHCC) definitions for WG, mPA and CSS, the Hammersmith criteria for CSS and the Sørensen criteria for WG and mPA.
Results: Ninety-nine PSV cases were identified. Fifty-six fulfilled criteria for WG (ACR), 60 for PAN (ACR) and 15 for CSS (ACR). Four fulfilled the Hammersmith criteria for CSS. Thirty-nine were defined as mPA (CHCC). Fifty-three patients fulfilled the Sørensen criteria for WG and three for mPA. Five of six patients classified as WG (ACR) who did not meet the Sørensen criteria were excluded by eosinophilia. Six patients who did not fulfil WG (ACR) met the Sørensen criteria for WG.
Conclusion: The classification of systemic vasculitis is complicated and many cases fulfil more than one set of criteria. The Sørensen criteria for WG is limited by its exclusion of eosinophilia despite reports of an association. We recommend that tissue eosinophilia or peripheral eosinophilia of <1.5x10(9)/l should not exclude a diagnosis of WG. With this modification, the Sørensen criteria for WG may be a useful method of classification, especially in confirming the classification of WG in patients who fulfil both WG (ACR) and mPA (CHCC). Few patients fulfilled the Sørensen criteria for mPA which suggests that they are not of value in classification.