DO TENDER JOINTS IN PSORIATIC ARTHRITIS REFLECT INFLAMMATION ON ULTRASOUND?

Background: Ultrasound (US) is a sensitive method for evaluating inflammation in arthritis, but several studies have shown discrepancies in inflammatory findings on US examination and clinically assessed disease activity, both in rheumatoid arthritis (RA) and psoriatic arthritis (PsA) (1, 2). In RA, a recent study found that swollen but not tender joints reflect synovitis detected by US (3). In PsA tenderness without joint swelling is a frequent finding. Objectives: To investigate the agreement of clinical joint evaluation (swollen joints (SJ) and tender joints (TJ)) and US findings of inflammation in PsA assessing joints and periarticular tissue involvement (e.g. joint capsule, adjacent ligaments etc.). Methods: We included 42 patients with active PsA (min. 3 swollen and tender joints) and hand involvement (min. 1 finger joint and/or 1 finger with dactylitis). All patients had US examination performed by one examiner (blinded to clinical data) using a high-end US scanner with a high-frequency 14 MHz linear transducer. 2-5th metacarpophalangeal- (MCP), proximal and distal interphalangeal (PIP and DIP) and 1-5th metatarsophalangeal (MTP) -joints were assessed by greyscale (GS) and power Doppler (PD) mode, bilaterally. Synovitis was scored for GS and PD change (0-3) according to OMERACT guidelines (4), PIP and DIP joints were additionally scored for volar synovitis (0-3) and presence of periarticular PD activity (PD activity in the joint capsule and/or adjacent structures). SJ (76) and TJ (78) counts were performed by an experienced rheumatologist blinded to US findings. As prevalence of lesions was low, agreement between TJ, SJ and US was calculated using the prevalence and bias adjusted Kappa (PABAK) on dichotomized values (0-1 vs 2-3 for GS scores (based on the highest score for each joint), 0 vs. 1-3 for PD scores). US synovitis was defined as GS>1 and PD>0. Results: Population characteristics and US findings are presented in table 1. Agreement between clinical and US joint evaluation is seen in table 2. There was poor agreement between TJ and US synovial hypertrophy and hyperaemia (PABAK 0.12 and 0.20, respectively) and fair agreement with periarticular PD (PABAK 0.25). Moderate agreement was found for SJ and intraarticular PD activity (PABAK 0.55). Our definition of US synovitis showed similar agreements with TJ and SJ as US hyperaemia. Conclusion: In this study TJ did not reflect intra- or periarticular US inflammation in PsA patients. SJ had a better agreement with US findings of inflammation, especially PD, which is in line with previous RA studies. References: [1]Michelsen B et al, Ann Rheum Dis. 2016 [2]Lackner A et al, Sem Artrihtis Rheum 2016 [3]Hammer HB et al, Ann Rheum Dis. 2019 [4]D’Agostino MA et al, RMD open. 2017 Disclosure of Interests: Sara Kamp Felbo Grant/research support from: Celgene, Charlotte Wiell: None declared, Mikkel Ǿstergaard Grant/research support from: AbbVie, Bristol-Myers Squibb, Celgene, Merck, and Novartis, Consultant of: AbbVie, Bristol-Myers Squibb, Boehringer Ingelheim, Celgene, Eli Lilly, Hospira, Janssen, Merck, Novartis, Novo Nordisk, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi, and UCB, Speakers bureau: AbbVie, Bristol-Myers Squibb, Boehringer Ingelheim, Celgene, Eli Lilly, Hospira, Janssen, Merck, Novartis, Novo Nordisk, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi, and UCB, Hilde Berner Hammer Consultant of: Has received fees as consultant from Roche, AbbVie and Novartis., Speakers bureau: Has received fees for speaking from AbbVie, BMS, Pfizer, UCB, Roche, MSD and Novartis, Marcin Szkudlarek: None declared, Lene Terslev Speakers bureau: LT declares speakers fees from Roche, MSD, BMS, Pfizer, AbbVie, Novartis, and Janssen.