28 August 2014 - 28 August 2014 - US provider of diagnostic information services Quest Diagnostics (NYSE:DGX) and its partners have discovered that increased  blood-serum levels of the 14-3-3eta protein did better in detecting rheumatoid arthritis (RA) than traditional antibody-serum testing, such as rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA, also known as antibodies to cyclic citrullinated peptides or CCP).

Data from the trial showed that 64% of patients with early RA were positive for 14-3-3eta versus 59% and 57% for either ACPA or RF, respectively. When findings of all three markers were investigated, 78% of participants with early-stage RA (3.4 months) and 96% of those with established RA (11.5 years) were detected. By comparison, 72% of patients with early-stage RA and 88% of those with established RA were diagnosed by just RF and/or ACPA.

The results further demonstrated that 14-3-3eta was more sensitive at identifying patients whose early blood test results by RF and ACPA were negative. In these "seronegative" patients, 14-3-3eta positively detected 21% of participants with early RA and 67% of those with established RA. Seronegativity in both early and established RA is a significant limitation of RF and ACPA, since it can delay start of treatment. 

Moreover, the relation of 14-3-3eta to detection of early RA may mirror a more severe phenotype of disease. The results showed that 14-3-3eta positive patients had notably worse disease based on clinical measures versus 14-3-3eta negative patients.

14-3-3eta serum levels were also found to be higher in people with early and established RA, versus healthy individuals and those in all control groups, indicating the biomarker may help distinguish patients with RA from those with certain other autoimmune diseases and healthy individuals.

Serum 14-3-3eta levels were also markedly higher in patients with early RA than in those with osteoarthritis, indicating that 14-3-3eta findings may help primary care doctors detect patients for referral to a rheumatologist. In addition, 14-3-3eta serum levels were notably higher in patients with erosive psoriatic arthritis (PsA) versus those with nonerosive PsA.

The findings are published in The Journal of Rheumatology.

Quest Diagnostics offers 14-3-3eta testing as part of its laboratory-developed IdentRA rheumatoid arthritis diagnostic panel, under a 14-3-3eta-biomarker licence deal with Canada-based Augurex Life Sciences.