AB1020 APPLICATION OF THE 2019 ACR/EULAR CLASSIFICATION CRITERIA CONTRIBUTES TO THE DIAGNOSIS OF IgG4-RELATED DISEASE
Authors: L. F. Chen, J. J. Liang, Z. M. Ouyang, J. D. MA, D. H. Zheng, L. Dai
Journal: Annals of the Rheumatic Diseases (2020)

Background: IgG4-related disease (IgG4-RD) is a rare and systemic disease characterized by swelling or masses in the involved organs, elevated serum IgG4, marked IgG4+ plasma cells infiltration and fibrosis. However, lacking of pathological data limited the definite diagnosis of IgG4-RD. As results of high-quality clinical and epidemiological investigations collected, new classification criteria for IgG4-RD were approved by ACR and EULAR in 2019. Whether this new criteria improve the diagnosis efficiency needs to be validated in clinical practice. Objectives: To applicate the 2019 ACR/EULAR classification criteria for the diagnosis of IgG4-RD in previously suspected patients and explore the clinical characteristics of patients with IgG4-RD according to the new classification criteria. Methods: Patients suspected of having IgG4-RD due to elevated serum IgG4 and swelling or masses in single or multiple organs were recruited in Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University from May 2013 and November 2019. Demographic and clinical data were collected. The diagnosis was reevaluated with the 2011 comprehensive diagnostic criteria (CDC) for IgG4-RD and the 2019 ACR/EULAR classification criteria for IgG4-RD, respectively. Results: (1) There were 68 patients recruited and 59(86.8%) of them had elevated serum IgG4 (≥135mg/dl) and 53(77.9%) patients showed swelling or masses in single or multiple organs. Most patients first visit general surgery (17.6%), gastroenterology (16.2%), respiratory medicine (16.2%) and rheumatology (14.7%). (2) According to the 2011 CDC for IgG4-RD, 4(5.9%) patients were definite IgG4-RD, 1(1.5%) was probable and 42(61.8%) were possible. According to the 2019 ACR/EULAR criteria, 20(29.4%) patients were diagnosed as IgG4-RD, including the 4 definite patients using the 2011 CDC. (3) Among the 20 IgG4-RD patients according to the 2019 ACR/EULAR criteria, 19(95.0%) were male and median age of symptom onset was 62(46~69) years. There were 6(30.0%) patients diagnosed at rheumatology, 5(25.0%) at gastroenterology, 3(15.0%) at general surgery, 2(10.0%) at respiratory medicine and 1(5.0%) at stomatology, endocrinology, orthopedics and urinary surgery, respectively. There were 9(45.0%) patients with bilateral lacrimal or salivary glands involved, 9(45.0%) with pancreas and biliary tree involved, 5(25.0%) with retroperitoneum involved, 2(10.0%) with kidney involved and 1(5.0%) with chest involved. (4) The median serum IgG4 of the 20 IgG4-RD patients was 15.40(4.14~55.10)g/L, median serum IgG was 27.9(17.2~50.2)g/L. There were 20.0%(4/20) patients had elevated serum eosinophil and 93.3%(14/15) had elevated serum IgE. There were 60.0%(9/15) patients had elevated C-reactive protein, 85.7%(12/14) had elevated erythrocyte sedimentation rate and 26.7%(4/15) had hypocomplementemia. There were 35.7%(5/14) patients had positive rheumatoid factor and 14.3%(2/14) had positive antinuclear antibodies. There were 6(30.0%) patients didn’t received biopsies, 8(40.0%) patients received surgical removal of salivary glands, lacrimal glands or pancreatic masses and 6(30.0%) patients received needle biopsies of the salivary glands or biopsies by bronchoscopy, gastroscopy or enteroscopy. (5) Among the patients didn’t fulfill the 2011 CDC and the 2019 ACR/EULAR criteria, there were 40 patients had elevated serum IgG4, whose serum IgG4 level were significant lower than those of IgG4-RD patients [3.66(2.39~7.68)g/L vs. 15.40(4.14~55.10)g/L, P &lt;0.001], and percentage of serum IgG4 ≥5× upper limit of normal were also lower than those of IgG4-RD patients (27.5% vs. 73.7%, P =0.002). Conclusion: The 2019 ACR/EULAR criteria can help diagnosing patients with IgG4-RD even lacking the tissue confirmation. Patients with moderately elevated serum IgG4 need more clinical evidence to diagnose IgG4-RD and exclude mimics. References: This work was supported by Guangdong Medical Scientific Research Foundation (grant no. A2017093). Disclosure of Interests: None declared