Blood test predicts at-risk individuals likely to develop RA in the short term
medwireNews: Researchers have validated a blood test involving B-cell receptor (BCR) clones that could determine which healthy individuals at risk for rheumatoid arthritis (RA) are likely to develop the condition in the short term.
The test, which is based on the presence of five or more dominant BCR clones, predicted the onset of RA within 3 years with a sensitivity of 100% and a specificity of 87%. The positive predictive value was 71% and the negative predictive value 100%.
Niek de Vries (Universiteit van Amsterdam, the Netherlands), presenting the findings at the EULAR 2018 meeting in Amsterdam, emphasized the need for such a test to better identify the 28% of individuals who develop arthritis in the short term, so within 1 to 3 years, who may benefit from early treatment.
The team used next-generation BCR sequencing to analyze the lymphocyte receptors in 2.5 mL samples of peripheral blood from 129 individuals at risk of RA. These lymphocyte receptors were amplified and the B-cell receptor clonal frequencies assessed.
At-risk individuals could then be divided into two groups based on an optimal number of five of these BCR clones ─ BCR-test negative (score <5) and BCR-test positive (score >5).
In his presentation, de Vries reported validation findings in a group of 129 individuals who had a history of arthralgia but not arthritis and were positive for the cyclic citrullinated peptide antibody and immunoglobulin M-rheumatoid factor.
Of these, 45 (35%) were BCR-positive and 84 (65%) were BCR-negative. Arthritis developed over the 3 years of follow-up in approximately 73% of individuals who tested positive and in none of those who tested negative. De Vries pointed out the importance of this latter finding so as to “reassure these patients in this respect.”
The team compared the BCR-test with the Risk Rule Model, which looks at a multitude of patient and clinical characteristics to predict future risk, and it performed significantly better in predicting arthritis onset.
They also found that the accuracy of the test improved in line with the number of BCR clones present. When they further divided their cohort into three groups by separating the BCR-positive patients into BCR-medium (score 5─8; 18%) and BCR-high (score >8; 17%), these individuals had differing risks for arthritis.
From this, de Vries and team were able to propose an algorithm for screening as the basis for further investigation, whereby BCR-negative patients had a 0% risk for developing arthritis in the short term ─ approximately the baseline risk in the general population ─ while the risk was 55% for BCR-medium individuals and 91% for those characterized as BCR-high.
De Vries noted that for the majority of BCR-high patients arthritis onset occurred after 1 year rather than 3 years.
“We think this group is really a group for intervention,” he recommended, “and the intermediate group we think should be retested.”
By Lucy Piper
medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group