Four novel autoantibody biomarkers could significantly improve diagnoses of rheumatoid arthritis, according to research presented at the annual congress of the European League Against Rheumatism in Madrid.
“Early detection is imperative,” researcher Liesbeth M. De Winter, MS, of the Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium, said in a press release. “If treated early, patients have a more than 50% chance of achieving remission — yet one-third of patients test negative to rheumatoid factor (RF) and anti-cyclic citrullinated peptide (ACCP).”
De Winter and colleagues used peptide ELISA to measure antibody reactivity against the four candidate biomarkers (UH-RA.1, UH-RA.9, UH-RA.14 and UH-RA.21) in a cohort of 127 patients with rheumatoid arthritis (RA), 97 healthy controls and 86 rheumatic controls, which included patients with psoriatic arthritis, ankylosing spondylitis, osteoarthritis and Sjögren’s syndrome. A validation cohort of 166 patients with RA also was screened.
Twenty-four percent of the 293 RA patients could not be identified using RF and ACCP, the current diagnostic biomarkers. Fifty-two early RA patients in the study had autoantibody response against the four biomarkers evaluated.
UH-RA.1, UH-RA.9, UH-RA.14 and UH-RA.21 demonstrated sensitivities of 8.7%, 1.6%, 4.7% and 18.1%, respectively, in the first cohort, with associated specificities for RA of 95%, 98%, 100% and 89%, respectively. When the biomarkers were combined, sensitivity reached 30% with 83% specificity. Thirty-four percent of the validation cohort tested positive on the biomarkers.
Researchers said the novel biomarkers identified 26% of the RF-negative ACCP-negative subpopulation, reducing the serological gap from 24% to 17%. UH-RA.1 and UH-RA.21 accounted for 7% and 17%, respectively, of the identified patients.
At least 37% of early RA patients tested positive on the biomarkers, including 12% on UH-RA.1 and 27% on UH-RA.21. Antibody reactivity against UH-RA.1 was associated with lower Disease Activity Score 28 (P=.016), negative RF status (P=.033) and visual analogue score (P=.016).
“The detection of antibody reactivity against our candidate biomarkers … implies that these biomarkers can be of additional value to the current diagnostic biomarkers for RA, with most promising results for UH-RA.1 and UH-RA.21,” the researchers concluded.
For more information:
De Winter L. OP0181: New Autoantibodies as Biomarkers for Early and Seronegative Rheumatoid Arthritis. Presented at: EULAR 2013; June 12-15, Madrid.