Biomarker could improve early rheumatoid arthritis diagnosis

A novel biomarker could make it easier for physicians to diagnose rheumatoid arthritis early, thereby improving their prospects. Researchers have found that identifying blood-serum levels of the 14-3-3eta protein provides better RA diagnostic capabilities than conventional antibody-serum testing. But the best results come when conventional antibody testing is combined with the new biomarker.

In a paper published in The Journal of Rheumatology, researchers from Quest Diagnostics ($DGX) and other institutions found that 64% of early rheumatoid arthritis patients were positive for 14-3-3eta, compared to levels for existing biomarkers of 59% for anticitrullinated peptide antibodies (ACPA) and 57% for rheumatoid factor (RF).

When all three markers were assessed in combination, 78% of early RA patients (who had had the disease for 3.4 months on average) and 96% of established RA patients (11.5 years mean years with the disease) were identified. That's a big improvement on the rates when ACPA and/or RF were used alone: 72% for early stage RA and 88% for established RA.

In patients whose RF and ACPA results were negative, a test for 14-3-3eta identified 21% of patients with early RA and 67% of those with established RA. Seronegativity can result in physicians delaying treatment.

"Our study demonstrates the clinical usefulness of 14-3-3eta for improved diagnostic capacity of testing for early RA. Combined testing of 14-3-3eta with established markers will help provide physicians with more definitive diagnostic information and help facilitate early treatment with disease-modifying antirheumatic drugs," said the study's principal investigator, University of Alberta professor Dr. Walter Maksymowych, in a statement.

Quest Diagnostics offers 14-3-3eta testing as part of its Rheumatoid Arthritis Diagnostic Panel IdentRA through a license with Augurex Life Sciences. This panel also includes RF and ACPA biomarker testing.

RA is an autoimmune disorder affecting an estimated 1.3 million American adults. The disease is a result of the immune system attacking the body's own tissues, especially the membranes that line the joints. Fluid builds up in the joints, causing pain and systemic inflammation.

Early symptoms of RA are often subtle. The study authors see the diagnosis and initiation of RA treatment within 12 weeks of symptom onset as crucial to preventing joint damage and improving long-term function and patient prognosis. But many patients are not diagnosed within this timeframe. An estimated 1.3 million American adults have rheumatoid arthritis.

To conduct the study, researchers analyzed the serum 14-3-3eta levels of 99 deidentified early RA patients and 135 deidentified established RA patients from various research centers. The levels were compared to those in a control group of 385 patients who were healthy or had osteoarthritis or another autoimmune disorder.

The study also found that early RA patients with 14-3-3eta may have a more severe phenotype of the disease; they had significantly worse disease based on clinical measures than did 14-3-3eta-negative RA patients. In addition, the levels of 14-3-3eta were higher in RA patients than in healthy individuals or those with osteoarthritis, a disease often difficult for physicians to distinguish from RA.

"The correlation between 14-3-3eta positivity and disease onset and severity may assist clinicians in personalizing the best course of treatment for the patient," said Dr. Stanley Naides, the medical director of immunology R&D at Quest.

- here is the release
- and the paper (sub. req.)

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