Session Title: Sjögren's Syndrome - Clinical
Session Type: Abstract Submissions (ACR)
Recently published ACR classification criteria for primary Sjögren’s syndrome (pSS) suggest considering antinuclear antibodies (ANA) titer and rheumatoid factor (RF) positivity in patients negative for anti-Ro/SSA antibodies. The diagnostic value of these tests for pSS has to be confirmed in independant cohorts. Besides, we have shown in a previous case-control study that blood B-cell subset profiling through (Bm2+Bm2’)/(eBm5+Bm5) ratio computation is abnormal in pSS patients. Gammaglobulins and IgG titers are often increased in these patients. The aim of this study was to evaluate the diagnostic value of these B-cell markers for pSS, and to assess if they could improve American-European Consensus Group (AECG) criteria.
This cross-sectional study was conducted in a monocentric cohort of patients with suspected pSS, prospectively included between November 2006 and September 2011. Clinical examination, basic biology, immunological tests and minor labial salivary gland biopsy (SGB) were performed systematically. For blood B-cell subset profiling, the (Bm2+Bm2’)/(eBm5+Bm5) ratio (referred to as B-cell ratio) was determined using flow cytometry. The gold standard for the analysis was a clinical diagnosis of pSS performed by a group of experts, blinded to the results of B-cell profiling. The diagnostic values and the independance of the different tests were compared using logistic regression analysis.
181 patients have been included in the study (mean age 56±13 years, symptoms duration 6.0±6.9 years, 92.2% females). 77 patients had pSS diagnosed by the experts. No differences were found between the 2 groups concerning age, disease duration, and sex ratio. The sensitivity (Se) and specificity (Sp) of the different tests were respectively: 60.6% and 99.0% for anti-SSA/SSB; 81.7% and 61.1% for ANA≥1:320; 70.4% and 83.2% for ANA≥1:640; 45.5% and 79.8% for IgM-RF; 42.3% and 97.9% for IgA-RF; 46.5% and 92.6% for gammaglobulins ≥14 g/l; and 49.6% and 91.6% for IgG ≥14 g/l. The mean B-cell ratio was significantly higher in the pSS group than in the non-pSS group (7.4±6.9 vs 3.2±2.3, P<0.001), and a ratio ≥5 had 52.1% Se and 83.2% Sp. Logistic regression analysis selected only ANA≥1:640 and B-cell ratio ≥5, with a similar weight. The combination of these two tests (ANA and ratio) displayed 37.7% Se and 96.2% Sp in the whole population, but only 12.9% Se in anti-SSA-negative patients. The association of the two tests (ANA or ratio) displayed 85.7% Se and 67.3% Sp in the whole group, and 71.0% Se in anti-SSA-negative patients. The modification of AECG criteria including the two tests in association (ANA or ratio) increased the Se from 83.1% to 90.9%, but decreased the Sp from 97.1% to 85.6%, whereas using the tests in combination (ANA and ratio) did not modify significantly their diagnostic value.
Blood B-cell subset profiling using flow cytometry is a simple test which has good diagnostic properties for pSS. However, the inclusion of this test, associated or not with ANA positivity, does not improve current classification criteria. Anti-SSA/SSB antibodies remain the best serologic item for the diagnosis of pSS.
J. O. Pers,
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