OP0217 IS METACARPOPHALANGEAL-JOINT PAIN AS AN EARLY SYMPTOM OF PATIENTS AT RISK FOR PROGRESSION TO INFLAMMATORY ARTHRITIS EXPLAINED BY MRI-DETECTED SUBCLINICAL INFLAMMATION? – A LARGE OBSERVATIONAL STUDY
Authors: Q. Dumoulin, X. Matthijssen, F. Wouters, A. Van der Helm - van Mil, E. Niemantsverdriet
Journal: Annals of the Rheumatic Diseases (2021)

Background: Pain in metacarpophalangeal (MCP)-joints in patients presenting with clinically suspect arthralgia (CSA) is one of the clinical features by which patients are considered at risk for progression to inflammatory arthritis (IA). As such this symptom is characteristic for CSA and therefore part of a list of clinical parameters determined by an EULAR-taskforce to identify a more homogeneous group of patients within CSA (the EULAR definition of arthralgia suspicious for progression to RA). MRI-detected subclinical inflammation is known to be present in patients with CSA. In general, arthralgia in CSA can be explained by this subclinical inflammation, however to date, the association of subclinical inflammation with pain in MCP-joints specifically is not clear. Subsequently, it is unknown whether this association differs pertinently when investigated with self-reported pain, or with pain in the form of tenderness at physical examination. Objectives: This study will investigate whether MCP-pain and MCP-joint tenderness are associated with MRI-detected subclinical inflammation in patients with CSA, and more specifically those who have progressed to IA. Methods: Between April 2012- February 2019, 602 patients were consecutively included in the Leiden clinically suspect arthralgia (CSA)-cohort. Follow-up ended when patients developed clinically apparent IA (determined at physical examination), or else after 2-years (median follow-up time 25 months). MCP-joints were assessed for self-reported joint pain by the patient using a mannequin and subsequently for joint tenderness by physical examination. Baseline unilateral MRIs of the MCP (2-5)-joints were scored by two readers, blinded for clinical data, on subclinical inflammation (synovitis, tenosynovitis, osteitis). Associations between MCP-pain or MCP-joint tenderness and MRI-detected subclinical inflammation were studied at patient level by logistic regression analyses, entering the mentioned MRI-detected features separately (univariable) and together (multivariable). Results: 33% of 227 patients with self-reported MCP-pain had MRI-detected subclinical inflammation and 38% of 226 patients with MCP-joint tenderness had MRI-detected subclinical inflammation. Self-reported MCP-joint pain was univariable associated with subclinical inflammation and synovitis in particular (OR 2.00, 95% CI: 1.21-3.30, OR 2.87, 95% CI: 1.29-6.39). In multivariable analysis this MCP-pain was associated with synovitis (OR 2.54, 95% CI: 1.12-5.77). MCP-joint tenderness was univariable associated with subclinical inflammation, and synovitis and tenosynovitis in particular (OR 1.84, 95% CI: 1.29-2.63, OR 1.76, 95% CI: 1.10-2.81, OR 1.69, 95% CI: 1.12-2.55, respectively). In multivariable analysis, tenosynovitis remained significant (OR 1.54, 95% CI: 1.00-2.36). Of all patients with self-reported MCP-joint pain who developed IA, 50% had MRI-detected subclinical inflammation. For MCP-joint tenderness this was 61%. Patients with MCP-joint tenderness without subclinical inflammation who developed IA, developed clinical arthritis at a joint that was not scanned (85%), hence they may have had subclinical inflammation that was not imaged. The other 15% did develop arthritis in an MCP-joint, suggesting that subclinical inflammation developed after CSA-onset. Conclusion: Arthralgia in the MCP-joints is associated with subclinical inflammation in CSA, in particular with synovitis and tenosynovitis. The prevalence of subclinical inflammation is highest for tender joints at physical examination; this can be acknowledged when applying the EULAR definition of arthralgia suspicious for progression to RA. Disclosure of Interests: None declared