Real World Experience Of The New Acr-Eular Classification Criteria For Igg4-Related Disease

Introduction IgG4-related hepatopancreatobiliary disease (IgG4-HPB) is part of a complex fibro-inflammatory systemic condition. It is critical to distinguish IgG4-HPB from malignant and inflammatory disease mimics to guide long-term management. The 2019 ACR/EULAR Classification Criteria for IgG4-related disease (IgG4-RD) were developed and validated in a large international cohort and reported to have excellent diagnostic specificity.1 We sought to evaluate this in real-world clinical practice through our supra-regional Oxford-London IgG4-RD multi-disciplinary meeting (MDM). Methods We prospectively collected data on 153 patients referred to our IgG4-RD MDM over 4-years with suspected IgG4-RD (Clin Med, Jan 2020 in press). Each was classified as definite, possible or not IgG4-RD based on existing diagnostic criteria (HISORt, CDC, Boston Histopathology) and speciality experience. We retrospectively applied the ACR-EULAR classification criteria to this cohort to assess concordance with MDM outcomes. Results All cases considered not IgG4-RD in the MDM (n=52) similarly did not meet ACR/EULAR criteria. Of those considered definite IgG4-RD (n=63) in the MDM, only half (33;52%) met ACR/EULAR criteria. In those with definite HPB involvement (n=48) in the MDM, just over half (27;56%) met ACR-EULAR criteria. Most of the IgG4-HPB patients not meeting ACR/EULAR criteria scored insufficient diagnostic points (n=17) due to reliance on pancreatic imaging characteristics; diffuse swelling and pseudocapsule, with no points awarded for cholangiopathy without pancreatic involvement, atrophy, or focal enlargement of the gland. Small and unrepresentative biopsies were an additional challenge. Specific exclusions were absence of glucocorticoid response in advanced (fibrotic) cholangiopathy, and Crohn’s disease or ulcerative colitis in isolated HPB involvement. Conclusions The ACR-EULAR classification demonstrated excellent specificity (100%) and will be an invaluable tool for clinical trials. Disparity between diagnosis according to our IgG4-RD MDM and the ACR/EULAR criteria are explained by specific pancreatic imaging characteristics, absence of cholangiopathy/hepatopathy as a unique entity, and the necessity for steroid responsiveness even if presenting with advanced cholangiopathy. Reference Wallace ZS, Naden RP, Chari S, et al. The 2019 American College of Rheumatology/European League against Rheumatism classification criteria for IgG4-related disease. Ann Rheum Dis 2020;79:77–87. doi:10.1136/annrheumdis-2019-216561