Diagnostic accuracy of blood B-cell subset profiling and autoimmunity markers in Sjögren’s syndrome
1 Service de Rhumatologie, Centre Hospitalier Régional et Universitaire de Brest, Hôpital de la Cavale Blanche, BP 824, F-29609 Brest cedex, France
2 EA 2216 Immunologie et Pathologie, Université de Brest, SFR ScinBios, Labex Imunotherapy, Graft, Oncology, BP 824, F-29609 Brest cedex, France
3 Service de Dermatologie, Centre Hospitalier Régional et Universitaire de Brest, Hôpital Morvan, BP 824, F-29609 Brest cedex, France
4 Explorations Fonctionnelles Neurologiques, Centre Hospitalier Régional et Universitaire de Brest, Hôpital de la Cavale Blanche, BP 824, F-29609 Brest cedex, France
Arthritis Research & Therapy 2014, 16:R15 doi:10.1186/ar4442Published: 17 January 2014
The aims of this study were to evaluate the diagnostic accuracy of blood B-cell subset profiling and immune-system activation marker assays in primary Sjögren’s syndrome (pSS) and to assess whether adding these tools to the current laboratory item would improve the American-European Consensus Group (AECG) criteria.
In a single-center cohort of patients with suspected pSS, we tested the diagnostic performance of anti-SSA, antinuclear antibody (ANA), rheumatoid factor (RF), gammaglobulins, IgG titers, and B-cell ratio defined as (Bm2 + Bm2′)/(eBm5 + Bm5), determined using flow cytometry. The reference standard was a clinical diagnosis of pSS established by a panel of experts.
Of 181 patients included in the study, 77 had pSS. By logistic regression analysis, only ANA ≥1:640 (sensitivity, 70.4%; specificity 83.2%) and B-cell ratio ≥5 (sensitivity, 52.1%; specificity, 83.2%) showed independent associations with pSS of similar strength. In anti-SSA-negative patients, presence of either of these two criteria had 71.0% sensitivity but only 67.3% specificity for pSS; whereas combining both criteria had 96.2% specificity but only 12.9% sensitivity. Adding either of these two criteria to the AECG criteria set increased sensitivity from 83.1% to 90.9% but decreased specificity from 97.1% to 85.6%, whereas adding both criteria in combination did not substantially modify the diagnostic performance of the criteria set. The adjunction of RF + ANA ≥1:320, as proposed in the new American College of Rheumatology (ACR) criteria, did not improve the diagnostic value of anti-SSA.
Blood B-cell subset profiling is a simple test that has good diagnostic properties for pSS. However, adding this test, with or without ANA positivity, does not improve current classification criteria.