Assessing the Diagnostic Accuracy of MRI in Early Rheumatoid Arthritis

According to a study published in Rheumatology, magnetic resonance imaging (MRI) has been shown to assist in identifying patients with unclassified arthritis (UA) who will develop rheumatoid arthritis (RA) — primarily in patients with UA presenting with oligoarthritis.

This study aimed to assess the diagnostic value of MRI in patients with early RA whose diagnosis cannot be made upon initial presentation. These patients present with UA, and although the use of MRI for early diagnosis of RA is recommended, there is limited evidence for its reliability.

This study consisted of 589 patients with UA from the Leiden Early Arthritis Clinic in The Netherlands (229 with RA, 159 with other arthritides and 201 with UA) who underwent MRI of the hand and foot. Preliminary studies compared MRIs of patients who presented with RA with symptom-free controls and patients with other arthritides. The value of MRI studies in early RA diagnosis was determined in patients with UA during 1-year follow-up and by using the 1987 RA diagnosis criteria — with the start of disease-modifying drugs as the outcome.

Preliminary investigations show that 14% of the patients with UA developed RA and 37% of these patients started disease-modifying treatment. Tenosynovitis, detected by MRI, was associated with RA development independent of other types of MRI-detected inflammation (odds ratio [OR]7.5, 95% CI 2.4, 23) and independent of age and other inflammatory measures (ie, swollen joints, elevated C-reactive protein [CRP]) [OR 4.2, 95% CI 1.4, 12.9].

The negative predictive value of abnormal tenosynovitis in patients with UA was 95% (95% CI 89%, 98%) and the positive predictive value was 25% (95% CI 17%, 35%). Studies showed that the performance was best in patients with UA presenting with oligoarthritis — 18% developed RA — with a positive predictive value of 36% (95% CI 23%, 52%), negative predictive value of 98% (95% CI 88%, 100%), sensitivity of 93% (95% CI 70%, 99%), and specificity of 63% (95% CI 51%, 74%).

In conclusion, patients with UA who present with a normal MRI were unlikely to develop RA. This study shows that MRI can be used in the early diagnostic process of RA.

Summary

• MRI-detected tenosynovitis was associated with the development of RA in patients with unclassified arthritis (UA) independent of other inflammatory measures, including swollen joints and elevated CRP.
• The negative predictive value for MRI tenosynovitis is high in RA, but its positive predictive value is limited.
• MRI was found to be the most diagnostic medium in patients with UA presenting with oligoarthritis (ie, 2 to 4 swollen joints).
• Patients with UA presenting with a normal MRI were unlikely to develop RA, suggesting that MRI can be used in the early diagnostic process of the disease.

Limitations

• There is a higher probability of a type II error since there were only a small number of cases in the subgroups of mono-, oligo- and polyarthritis as a result of only 29 patients with UA developing RA.
• The OMERACT rheumatoid arthritis MRI (RAMRIS) method used to score the MRIs is not designed for diagnostic purposes and may hamper direct clinical implementation.
• Dichotomization of normal vs abnormal MRI findings generally results in a loss of information and discriminative value.
• Cost-effectiveness of MRI was not addressed, nor was the extent to which scanning of hand and foot joints is required, or whether a limited region would be equally informative.

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Reference

Nieuwenhuis WP, van Steenbergen HW, Mangnus L, et al. Evaluation of the diagnostic accuracy of hand and foot MRI for early rheumatoid arthritis [published online April 27, 2017]. Rheumatology. doi:10.1093/rheumatology/kex167