Background/Purpose:

The 2010 ACR/EULAR criteria for rheumatoid arthritis (RA) identify RA patients earlier than the 1987 ACR criteria. However, still a considerable amount of patients not fulfilling the 2010 criteria or other rheumatic diagnoses (i.e. undifferentiated arthritis, UA) develop RA.^1,2Previous studies revealed that auto-antibodies and existing prediction rules fail to identify the UA patients that will progress to RA. In this observational study we studied the use of MRI-detected inflammation to identify these UA patients.

Methods:

202 patients presenting with 2010UA consecutively included in our early arthritis cohort were studied. Unilateral, 1.5T extremity MRI of the metacarpophalangeal, wrist and metatarsophalangeal joints was performed at baseline. Bone marrow edema (BME), synovitis and tenosynovitis were scored according the RA MRI scoring system by 2 independent readers blinded for clinical data. MRI positivity was defined as the presence of inflammation with a prevalence <5% in age matched symptom free controls. Clinical and laboratory findings were also recorded. Two outcome measures were studied; fulfilling the 1987 ACR RA criteria and initiation of DMARD therapy within the first year.

Results:

The 202 UA-patients had a median symptom duration of 8.7 weeks; 29 patients (14%) progressed to RA and 75 (37%) started DMARD therapy. A positive MRI for any MRI inflammation was associated with both RA development (OR 6.1 95%CI 1.4-26.8) as well as initiation of DMARD-therapy (OR 2.4 95%CI 1.2- 4.6). When assessing the MRI features BME, synovitis and tenosynovitis separately, only tenosynovitis was associated with RA development and initiation of DMARD-therapy (OR 5.4 95%CI 1.9-15.2 and OR 4.2 95%CI 2.3-7.8 respectively). When evaluating traditional inflammatory measures, the swollen joint count at baseline (SJC) and C-reactive protein level at baseline (CRP) were also associated with RA-development, in contrast to the presence of ACPA or RF. Multivariable analyses including SJC and CRP with RA-development as outcome, yielded ORs of 5.6 (95%CI 1.2-25.6) for any MRI detected inflammation and 6.3 (95%CI 2.1-19.3) for MRI detected tenosynovitis. Similar analyses with initiation of DMARD therapy as outcome yielded ORs of 1.8 (95%CI 0.9-3.6) and 3.6 (95%CI 1.9-6.9) respectively.

Conclusion:

Within 2010UA, a positive MRI was associated with RA development, independent of commonly used measures of inflammation (SJC, CRP). MRI detected tenosynovitis in particular was most predictive. The next step is to determine the clinical benefit of extremity MRI to enable an early diagnosis of RA.

References:

1. Krabben A et al. Ann Rheum Dis2012;71:238–41.
2. Krabben A et al. Rheumatology 2013;52:1265–70.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/is-mri-of-use-in-identifying-which-undifferentiated-arthritis-patients-will-develop-ra/