Magnetic resonance imaging evidence of bone edema in the wrist and metatarsophalangeal joints was an independent predictor of future development of rheumatoid arthritis in a prospective Danish study of patients with early undifferentiated arthritis.
Incorporating MRI bone edema findings, together with clinical and biochemical parameters, yielded a prediction model that showed unprecedented accuracy in identifying which patients would or would not develop rheumatoid arthritis, Dr. Anne Duer-Jensen of Copenhagen University Hospital at Hvidovre and Copenhagen University Hospital at Glostrup, and her associates reported in Arthritis & Rheumatism (2011;63:2192-202).
The study involved 116 patients with early undifferentiated arthritis, 23% of whom went on to meet American College of Rheumatology 1987 criteria for RA during a median 17 months of follow-up. They were matched with 24 healthy controls. The predictive model had a sensitivity of 81% and a specificity of 82% for progression to RA. Thus, it classified 82% of patients correctly.
That’s a markedly better predictive accuracy than achieved when the investigators applied the published and validated van der Helm-van Mil prediction model to the same study population. The van der Helm-van Mil model (Arthritis Rheum. 2007;56:433-40) had a 60% predictive accuracy.
Participants in the Danish study had two or more tender joints and/or two or more swollen joints among the wrist, metatarsophalangeal (MTP), proximal interphalangeal, or metacarpophalangeal joints for more than 6 weeks but less than 2 years. None of the 116 subjects had a specific rheumatologic diagnosis at baseline. Thus, they were typical of the patients often referred to rheumatologists for early undifferentiated arthritis, a condition that can morph into osteoarthritis, RA, persistent arthralgias, or nonprogressive disease.
The investigators developed their predictive model based on the findings of a multivariate logistic regression analysis that encompassed numerous variables. The final prediction model included four independent predictors of RA: serum positivity for rheumatoid factor, the presence of hand arthritis, morning stiffness lasting longer than 1 hour, and the MRI summary score for bone edema in the wrist and MTP joints that grew out of the Outcome Measures in Rheumatology Clinical Trials, or OMERACT (J. Rheumatol. 2003;30:1385-6).
Of note, in the Danish study the presence of rheumatoid factor was an independent predictor of subsequent RA, whereas a positive anti–cyclic citrullinated peptide test was not, unlike in several recent studies. MRI summary scores for bone edema proved to be a significantly more potent predictor of RA than MRI scores for synovitis or erosion.
The formula for the current iteration of the prediction model is cumbersome. A simpler version would be welcome. Toward that end, the investigators tried using MRI bone edema scores for the wrist or MTP joints alone, but they found that it unacceptably weakened the model’s predictive power.
The next step in this project will be to see how the prediction model performs in other cohorts of patients with early undifferentiated arthritis. The goal is to develop a tool that enables physicians to extend the current, highly successful early and aggressive treatment strategy for RA into the pre-RA setting.
This study was funded by the Danish Rheumatism Foundation and other foundation grants. While Dr. Duer-Jensen reported having no financial conflicts of interest, several of her associates did. Those can be found on the full text of the journal article.