Background The phase of arthralgia is the earliest moment to clinically recognize patients who will develop Rheumatoid Arthritis (RA). Previous imaging studies in the phase of arthralgia without clinical arthritis showed that subclinical inflammation precedes RA development. It is unknown which symptoms and characteristics relate to subclinical joint inflammation as measured by MR-imaging. Among all arthralgia patients, those with Clinically Suspect-type Arthralgia (CSA) are suspect to progress to arthritis according to the clinical judgment of their rheumatologists.
Objectives We determined the symptoms and characteristics of patients with Clinically Suspect Arthralgia that had inflammation on MRI.
Methods 102 patients with CSA and without clinical arthritis were included. At baseline, they filled questionnaires, underwent joint counts and unilateral 1.5T MRI of MCP2-4, wrist and MTP1-5 joints. Synovitis, bone marrow edema (BME) and tenosynovitis were scored according to the RAMRIS method. Symptoms and signs were related to MRI-inflammation (based on MRI-scores in symptom free controls, a sum of the scores for synovitis, BME and tenosynovitis ≥3 was considered as positive for MRI-inflammation). Whether certain clinical characteristics and MRI-inflammation frequently occurred together was studied by Partial Least Squares regression. All CSA patients were followed longitudinally.
Results 44% of the CSA patients had subclinical MRI-inflammation. Synovitis was the most prevalent inflammatory feature on MRI (20%). Patients with MRI-inflammation were older and more frequent anti-citrullinated peptide antibodies (ACPA)-positive than patients without MRI-inflammation (p<0.001 and 0.049 respectively). A combination of symptoms and characteristics (including subacute symptom onset, initial localization in large joints, or in lower extremities, morning stiffness ≥60 minutes, elevated acute phase reactants and presence of autoantibodies) explained 42% of the variance in MRI-inflammation. Hence, no specific combination of characteristics was found to be discriminative for the presence of subclinical inflammation. Despite a still limited follow-up duration, 35% of the patients with MRI-detected subclinical inflammation that were followed for at least four months developed clinical arthritis or RA.
Conclusions Subclinical inflammation as measured by MRI is present in 44% of CSA patients. A combination of symptoms/characteristics incompletely differentiated patients with and without MRI-inflammation. Follow-up will reveal which characteristics relate to RA development.
Disclosure of Interest None declared
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