AB0765 CAN A 6-JOINT ULTRASOUND SCORE DIFFERENTIATE RHEUMATOID ARTHRITIS FROM PSORIATIC ARTHRITIS? A CROSS SECTIONAL STUDY
Authors: F. Figus, L. Idolazzi, P. Perić, A. Zabotti, I. Tinazzi, I. Azzolin, E. Montabone, T. Sapundzhieva, A. Batalov, P. Todorov, R. Karalilova, A. Iagnocco
Journal: Annals of the Rheumatic Diseases (2020)

Background: Ultrasonography (US) is a well established technique both for diagnosis and follow up in Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PSA) 1 . To date, there is no consensus regarding a standardized US evaluation of joint involvement by a validated score to be used for differential diagnosis. Objectives: 1) To differentiate the ultrasound features of patients affected by active RA or active PSA by using a 6-joints score 2 . 2) To analyze correlations between those findings and clinical patterns of PSA disease. Methods: 68 RA and 38 PSA patients (divided in two equal subgroups according to the clinical involvement i.e. polyarticular or oligoarticular) were enrolled in a multi-center cross-sectional study. All patients underwent clinical evaluation including demographic data, disease characteristics, laboratory test and tender/swollen joints count. SDAI and DAPSA were calculated in accordance to the disease and standard of care. The sonographic evaluation of wrists, II MCFs and knees, was performed using a multifrequency linear probe (13-18 MHz) with power Doppler (7.5 MHz, PRF500 Hz). High-end equipment was used and the scanning technique as well as the lesion assessment was previously agreed among the participants, who performed a consensus session 100 images. A validated ultrasound score 2 , which included effusion, synovial hypertrophy and synovial hypervascularization at 6 joints sites was used. Those lesions were assessed according to OMERACT definitions and semi-quantitatively graded (0-3). By summing the scores obtained at each joint site and globally, a joint score for articular involvement, a score for the severity of each lesion and a global 6-joint score for all abnormalities were calculated. Results: Clinical evaluation showed no statistically significant differences between RA and PSA (table I). Ultrasound detected significant differences in the score of joint effusion (SE) (p&lt;0.021), synovial hypertrophy (SH) (p&lt;0.001) and Doppler signal (p&lt;0.011) between oligoarticular PSA and RA. Significant differences in the joint score of II MCF (p&lt;0.000) and wrist (p&lt;0.032) were also found between oligoarticular PSA and RA. The global 6-joint score was 10,88 in RA, 6,05 in PSA oligoarticular, 16,32 in PSA polyarticular. No differences were found between RA and polyarticular PSA. Conclusion: Ultrasound evaluation of 6 target joints might help to discriminate RA and PSA oligoarticular subset. The study of a limited number of joints is therefore a complementary tool to the clinic, fast and well integrated into the overall assessment of the arthritic patient. References: [1]Zabotti A. et al. Clin Exp Rheumatol. 2018; 36:519-525. [2]Perricone C et al. Rheumatology (Oxford) 2012; 51:866-73. Table 1. Dependent variables Study Population p values US_SEScore RA PSA OLIGO .021 PSA POLY .356 PSA RA .021 OLIGO PSA POLY .014 PSA RA .356 POLY PSA OLIGO .014 US_SHScore RA PSA OLIGO .001 PSA POLY .336 PSA RA .001 OLIGO PSA POLY .004 PSA RA .336 POLY PSA OLIGO .004 US_PDScore RA PSA OLIGO .011 PSA POLY .102 PSA RA .011 OLIGO PSA POLY .006 PSA POLY RA .102 PSA OLIGO .006 US_MCP2Score RA PSA OLIGO .000 PSA POLY .276 PSA RA .000 OLIGO PSA POLY .002 PSA POLY RA .276 PSA OLIGO .002 US_WRISTScore RA PSA OLIGO .032 PSA POLY .610 PSA RA .032 OLIGO PSA POLY .047 PSA POLY RA .610 PSA OLIGO .047 US_KNEEScore RA PSA OLIGO 1.000 PSA POLY .133 PSA OLIGO RA 1.000 PSA POLY .180 PSA POLY RA .133 PSA OLIGO .180 US_KNEEScore RA PSA OLIGO 1.000 PSA POLY .133 PSA RA 1.000 OLIGO PSA POLY .180 PSA POLY RA .133 PSA OLIGO .180 US: ultrasound; SE synovial effusion; SH synovial hypertrophy; PD power Doppler; MCP metacarpophalangeal; PSA psoriatic arthritis; OLIGO oligoarticular; POLYpolyarticular Disclosure of Interests: Fabiana Figus: None declared, Luca Idolazzi: None declared, Porin Perić: None declared, Alen Zabotti Speakers bureau: Celgene, Janssen, Ilaria Tinazzi: None declared, Irene Azzolin: None declared, ERIKA MONTABONE: None declared, Tanya Sapundzhieva: None declared, Anastas Batalov: None declared, PLAMEN TODOROV: None declared, Rositsa Karalilova: None declared, Annamaria Iagnocco Grant/research support from: Abbvie, MSD and Alfasigma, Consultant of: AbbVie, Abiogen, Alfasigma, Biogen, BMS, Celgene, Eli-Lilly, Janssen, MSD, Novartis, Sanofi and Sanofi Genzyme, Speakers bureau: AbbVie, Alfasigma, BMS, Eli-Lilly, Janssen, MSD, Novartis, Sanofi