APPLICATION OF THE NEW 2022 ACR/EULAR CLASSIFICATION CRITERIA FOR CALCIUM PYROPHOSPHATE DEPOSITION DISEASE (CPPD) IN A COHORT OF PATIENTS DIAGNOSED WITH SERONEGATIVE RHEUMATOID ARTHRITIS

H. Codes-Mendez, L. Sainz Comas, H. Park, A. M. Millán Arciniegas, B. Magallares, P. Moya, J. L. Tandaipan, S. P. Fernandez-Sanchez, S. Ros, A. Laiz, I. Castellví, H. Corominas, C. Díaz-TornéHospital de la Santa Creu i Sant Pau, Rheumatology, Barcelona, Spain Universitat Autònoma de Barcelona, Medicine, Bellaterra, Spain  Background The ACR/EULAR group released the first-ever provisional classification criteria for calcium pyrophosphate deposition disease (CPPD) at the ACR congress in November 2022. These criteria are based on an adjusted domain scoring system including demographic, clinical and radiological characteristics, and synovial fluid crystal analysis. The differential diagnosis in CPPD must be made with rheumatoid arthritis (RA) and monosodium urate crystal deposition disease. Objectives To study the percentage of patients diagnosed with seronegative RA who meet the new 2022 ACR/EULAR classification criteria for CPPD (final score ≥57). To determine the clinical and demographic differences between patients with a diagnosis of seronegative RA who meet or not the classification criteria for CPPD. Methods An observational retrospective cross-sectional study was performed including all the patients from a monographic RA clinic between September and December 2022. Demographic, clinical, analytical and imaging variables (simple radiology and ultrasound) were collected. The 2022 ACR/EULAR provisional classification criteria for CPPD were applied. Results Overall, 364 patients with RA were identified and those with seropositivity for RF and/or ACPAs were excluded. A total of 96 (24.4%) patients were included, 74.7% females, with a mean age at onset of symptoms of 59.3 (±16.4) years and 8.35 years of disease duration. A total of 18 patients (18.9%) met the classification criteria for CPPD. The characteristics and differences between the patients who met or not the criteria are shown in Table 1. The patients who met the CPPD criteria were older (p=0.048) and had a different clinical presentation (p=0.010) relating to the time-course of inflammatory arthritis (persistent, 1 typical episode, >1 typical episode, others). No significant differences were observed between groups in the location of joint clinical involvement. There was a statistically significant association (p=0.000) between the presence of radiological chondrocalcinosis (CC) and the fulfillment of criteria for CPPD, being detected in 66.6% of patients with CPPD versus none with seronegative RA without CPPD. Similarly, there was a significant association (p=0.000) between osteoarthritis in typical locations for CPPD (bilateral radiocarpal, scaphoid/trapezium/trapezoid without rhizarthrosis, 2nd and 3rd MCF) and compliance with criteria for CPPD, being detected in 55.5% of patients with CPPD. A higher prevalence of erosions was detected in patients with CPPD (44.4%) versus seronegative RA without CPPD (27.3%), without statistical significance. No significant treatment differences were observed in both subgroups. Of the patients with criteria for CPPD, 74% were being treated with synthetic of biological disease modifying antirheumatic drugs (DMARDs). Table 1. Characteristics of the sample according to the fullfilment or not of the new 2022 ACR/EULAR classification criteria for CPPD. Total (n=95) Seronegative RA with CPPD* (n=18) Seronegative RA without CPPD (n=77) p Female gender, n (%) 71 (74.7%) 16 (88.8%) 55 (71.4%) 0.142 Age at onset (years), p50 63 69.5 61 0.048 Disease duration (years), p50 7 6 7 0.952 Time-course, n (%) 0.010 - Persistent arthritis 38 (40%) 4 (21.1%) 34 (44.5%) - 1 typical episode 0 (0%) 0 (0%) 0 (0%) - >1 typical episode 39 (41.1%) 13 (72.2%) 26 (33.8%) - Others 18 (18.8% 1 (5.3%) 17 (22.1%) Erosions, n (%) 29 (30.5%) 8 (44.4%) 21 (27.3%) 0.091 Treatment, n (%) 0.854 Prednisone 21 (21.9%) 4 (21.1%) 17 (22.1%) sDMARD 45 (46.9%) 10 (52.6%) 35 (45.5%) bDMARD 19 (20% 3 (16.6%) 4 (20.8%) Combination therapy 10 (10.4%) 1 (5.3%) 9 (11.7%) Conclusion A total of 18 (18.9%) patients with seronegative RA from a monographic RA unit met the new 2022 ACR/EULAR provisional classification criteria for CPPD. Age at diagnosis and clinical presentation were different between patients with RA who met criteria for CPPD and those who did not. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests None Declared. Keywords: Crystal Arthritis, Descriptive Studies, Rheumatoid arthritis DOI: 10.1136/annrheumdis-2023-eular.2302Citation: , volume 82, supplement 1, year 2023, page 253Session: All about Crystal arthritis I (Poster Tours)