A Technically Sound Biomarker for axSpA, But Is It Aimed at the Right Patient Population?
Could this be developed to be a population screening test?
The persistent 5-to-10-year diagnostic delay in axial spondyloarthritis (axSpA) can lead to irreversible spinal damage. Limited access to tools like MRI and HLA-B27 typing has fueled the search for a simple, robust blood test to aid in earlier diagnosis (perhaps as a population screening tool). The 14-3-3η (eta) autoantibody (AAb) multiplex assay is one such promising candidate.
Biological Significance
The 14-3-3 family of proteins is are highly conserved regulatory molecule involved in various cellular processes. The presence of extracellular 14-3-3η and the development of autoantibodies against it point to a specific immune response that may be involved in the pathophysiology of axSpA. Previous work has suggested these autoantibodies could be biomarkers for both inflammation and the potential for radiographic progression in ankylosing spondylitis, making their measurement a rational approach for a diagnostic tool.
Study Design at a Glance
At the EULAR 2025 congress, a study was presented to validate the technical and clinical performance of this new 14-3-3η AAb assay.
The primary goal was to assess the assay's reliability and its ability to distinguish patients with a confirmed axSpA diagnosis from a control group.
The clinical validation cohort consisted of 83 patients with axSpA and 57 presumed healthy subjects.
The researchers utilized Receiver Operator Characteristic (ROC) curve analysis to identify the five most informative peptides and developed a composite scoring model to enhance diagnostic potential.
Assay Performance and Key Results
The study's findings indicate a technically sound and reliable assay.
Technically, the test demonstrated high precision and an overall accuracy of 96.0% in its measurements. It also showed minimal interference from common substances in the blood.
Clinically, the assay showed a clear distinction between the axSpA and healthy control groups. When using the composite score, the model produced an Odds Ratio of 8.7 for an axSpA diagnosis.
A patient with a positive composite score had a Relative Risk of 2.9 for an axSpA diagnosis, while a patient with a negative score had a Relative Risk of just 0.3.
A Clinician's Perspective on the Path Forward
The true diagnostic dilemma in early axSpA often arises in patients who present without the classic hallmarks of disease—they may lack elevated inflammatory markers, definitive radiographic changes, or other systemic features. A highly specific and sensitive blood test would be revolutionary for this very population.
This study successfully demonstrates that the 14-3-3η AAb assay can reliably differentiate diagnosed axSpA patients from healthy individuals, which is a foundational requirement for any new diagnostic test. This work confirms the assay's technical robustness and its potential clinical utility.
However, the critical question for clinicians remains: how does this test perform in the real-world scenario of differentiating early axSpA from the vast spectrum of mechanical and other inflammatory back pain conditions? Answering this question will be the next pivotal step. Future research in cohorts of patients with undifferentiated back pain is necessary to fully establish the role of this biomarker in shortening the diagnostic odyssey for our patients.
Source Abstract:
Marotta A, Liggett J, Maksymowych WP, et al. POS0717: Validation of Anti-14-3-3η (eta) Multiplex Laboratory Developed Test (LDT) for the Diagnosis of Axial Spondyloarthritis (axSpA). Ann Rheum Dis. Published online for EULAR 2025. doi:10.1136/annrheumdis-2025-eular.1600