In patients with juvenile idiopathic arthritis (JIA), metacarpophalangeal (MCP) joints should be included in the MRI wrist scoring system to have a more accurate assessment of disease activity and treatment efficacy, according to data published in The Journal of Rheumatology.

Researchers evaluated the precision of an MRI-based synovitis score of the MCP joints, comparing the metric properties of the original and an extended MRI wrist score in a cohort of patients with JIA. A total of 70 patients with JIA (55 women) were scored by 3 independent readers based on the wrist component of the rheumatoid arthritis MRI synovitis score, including distal radioulnar, radiocarpal, and combined midcarpal and carpometacarpal joints, and an extended score, including the MCP joints. Thirty-eight patients had follow-up at 1 year.

For the original and extended scores, interreader agreements were moderate (intraclass correlation coefficient [ICC], 0.77; 95% CI, 0.68-0.84) and good (ICC, 0.86; 95% CI, 0.80-0.91). Strong evidence demonstrated that the ICC for the extended score was significantly better than the ICC for the original score (P =.002). In the 2 less experienced readers, the ICC ranged from 0.82 for the wrist component of the rheumatoid arthritis MRI scoring (RAMRIS) system to 0.86 for the extended score (95% CI, 0.73-0.88 and 0.78-0.91, respectively).

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Mean differences were −0.4 for the original RAMRIS score and −0.6 for the extended score (95% limits of agreement, −3.4 to 2.6 and −6.7 to 5.5, respectively). Weighted Cohen’s kappa of the individual joints demonstrated good agreement for the original score and good to excellent agreement for the extended score. Correlations with clinical variables that were reflective of disease activity showed improvement for the extended score, with the standardized response mean higher compared with that of the original score.

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Investigators concluded that in patients with JIA, use of the extended score demonstrated better reliability, construct validity, and sensitivity to change than the original score. For a more precise assessment of disease activity and treatment effectiveness in individuals with JIA, inclusion of MCP joints should be considered in the scoring system. The high sensitivity of the extended MRI score in the detection of inflammatory changes renders this imaging technique a promising outcome measure for evaluating the efficacy of therapy in patients with JIA.

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van Dijkhuizen EHP, Vanoni F, Magnano GM, et al; for the the OMERACT Working Group MRI in JIA . Effect of the inclusion of the metacarpophalangeal joints on the wrist magnetic resonance imaging scoring system in juvenile idiopathic arthritis [published online August 15, 2018]. J Rheumatol. doi:10.3899/jrheum.171246