Confirmation of antiphospholipid antibody positivity: a year's results in a cohort of 113 patients

Objective: To evaluate the confirmation rate of antiphospholipid antibodies (aPL), to analyze their behaviour at confirmation time, and to study the clinical value of their confirmation. Methods: Blood samples from 380 subjects, enrolled in this study from June 1, 2007 to May 31, 2008, were tested for anti-cardiolipin (aCL) and anti-beta2glycoprotein (aβ2GPI) antibodies using an ELISA method and for Lupus anticoagulant (LA) using a series of clotting tests. The samples of the 113 subjects resulting positive at the first testing time were assayed again to confirm antiphospholipid positivity. Results: aPL positivity was confirmed in 67 out of the 113 subjects (59.3%). Medium-high antibody levels of all, except IgM aCL, aPL/ELISA had a significantly higher confirmation rate with respect to that in subjects with low levels. The confirmation rate in the category I antibody patients (multiple positivity) was higher than that in the category II antibody subjects (single positivity). LA positivity was confirmed only when it was associated to other aPL. The cut-off of 40 GPL produced a confirmation rate equal to that resulting from a 99th percentile cut-off. Confirmation of aPL positivity made it possible for us to confirm the diagnosis of antiphospholipid syndrome (APS) in 8 out of the 113 subjects originally resulting positive (7,1%). APS clinical features were vascular thrombosis in 4 of these and pregnancy morbidity in the other 4. Conclusions: Our data emphasize aPL positivity confirmation selectivity, and medium-high antibody levels and category I antibodies (multiple positivity) had the best confirmation rates

Clinical value of antibodies to lysobisphosphatidic acid in patients with primary antiphospholipid sindrome

To assess the clinical value of anti-lysobisphosphatidic acid (anti-LBPA) antibodies in patients with primary antiphospholipid syndrome (APS), the sera of 140 primary APS patients were tested and compared with those of 70 control subjects affected with rheumatic systemic diseases (n. 24) or autoimmune thyroiditis (n. 46). Anti-LBPA anticardiolipin (aCL) and anti-β2 Glycoprotein I (anti-β2GPI) antibodies were determined using a “home made” ELISA method. Lupus anticoagulant (LA) was assessed using a series of clotting tests in accordance with the literature. IgG anti-LBPA was significantly prevalent in primary APS (p=0.000) with a sensitivity of 58.6% and a specificity of 92.9%. IgM anti-LBPA showed a significant frequency in primary APS (p=0.000) with a sensitivity of 28.6% and a specificity of 97.1%. Anti-LBPA’s sensitivity and specificity for APS were lower or equal to those of aCL and anti-β2GPI. The prevalence of anti-LBPA in the different clinical and laboratory subsets of APS was lower than those of aCL and anti- β2GPI. It is interesting to observe that both IgG and IgM anti-LBPA were never found alone. The comparison between anti-LBPA and LA showed that the former had a higher sensitivity but a lower specificity. In conclusion, in view of our results anti-LBPA cannot at present be considered a further tool to be utilized to diagnose APS and to differentiate the different clinical and laboratory subsets of this disease

Clinical value of antibodies to lysobisphosphatidic acid in patients with primary antiphospholipid syndrome.

To assess the clinical value of anti-lysobisphosphatidic acid (anti-LBPA) antibodies in patients with primary antiphospholipid syndrome (APS), the sera of 140 primary APS patients were tested and compared with those of 70 control subjects affected with rheumatic systemic diseases (n. 24) or autoimmune thyroiditis (n. 46). Anti-LBPA anticardiolipin (aCL) and anti-β2 Glycoprotein I (anti-β2GPI) antibodies were determined using a "home made" ELISA method. Lupus anticoagulant (LA) was assessed using a series of clotting tests in accordance with the literature. IgG anti-LBPA was significantly prevalent in primary APS (p=0.000) with a sensitivity of 58.6% and a specificity of 92.9%. IgM anti-LBPA showed a significant frequency in primary APS (p=0.000) with a sensitivity of 28.6% and a specificity of 97.1%. Anti-LBPA's sensitivity and specificity for APS were lower or equal to those of aCL and anti-β2GPI. The prevalence of anti-LBPA in the different clinical and laboratory subsets of APS was lower than those of aCL and anti- β2GPI. It is interesting to observe that both IgG and IgM anti-LBPA were never found alone. The comparison between anti-LBPA and LA showed that the former had a higher sensitivity but a lower specificity. In conclusion, in view of our results anti-LBPA cannot at present be considered a further tool to be utilized to diagnose APS and to differentiate the different clinical and laboratory subsets of this disease

Clinical value of antibodies to lysobisphosphatidic acid in patients with primary antiphospholipid syndrome.

To assess the clinical value of anti-lysobisphosphatidic acid (anti-LBPA) antibodies in patients with primary antiphospholipid syndrome (APS), the sera of 140 primary APS patients were tested and compared with those of 70 control subjects affected with rheumatic systemic diseases (n. 24) or autoimmune thyroiditis (n. 46). Anti-LBPA anticardiolipin (aCL) and anti-beta2 Glycoprotein I (anti-beta2GPI) antibodies were determined using a "home made" ELISA method. Lupus anticoagulant (LA) was assessed using a series of clotting tests in accordance with the literature. IgG anti-LBPA was significantly prevalent in primary APS (p=0.000) with a sensitivity of 58.6% and a specificity of 92.9%. IgM anti-LBPA showed a significant frequency in primary APS (p=0.000) with a sensitivity of 28.6% and a specificity of 97.1%. Anti-LBPA's sensitivity and specificity for APS were lower or equal to those of aCL and anti-beta2GPI. The prevalence of anti-LBPA in the different clinical and laboratory subsets of APS was lower than those of aCL and anti-beta2GPI. It is interesting to observe that both IgG and IgM anti-LBPA were never found alone. The comparison between anti-LBPA and LA showed that the former had a higher sensitivity but a lower specificity. In conclusion, in view of our results anti-LBPA cannot at present be considered a further tool to be utilized to diagnose APS and to differentiate the different clinical and laboratory subsets of this diseas

The clinical significance of autoantibodies directed against prothrombin in primary antiphospholipid syndrome.

Abstract BACKGROUND:To evaluate the clinical significance of IgG/IgM antibodies directed against prothrombin (PT) in a homogeneous cohort of patients with primary APS (PAPS). METHODS:IgG/IgM anti-prothrombin (aPT) antibodies were measured using a commercial ELISA kit in 158 PAPS patients and in 214 control subjects (100 healthy blood donors and 114 patients with autoimmune diseases). RESULTS:IgG/IgM aPT antibodies were significantly associated with PAPS (OR, 95% CI: 52.0, 7.0-385.5; 9.8, 1.2-80.8, respectively). They were found to have a high specificity (IgG 99.50%, IgM 99.54%) but a low sensitivity (IgG 19.60%, IgM 3.80%) for PAPS. IgG aPT antibodies were significantly higher in the PAPS patients with thrombosis (OR, 95% CI: 69.2, 9.2-519.1) as well as in those with pregnancy morbidity alone (OR, 95% CI: 20.5, 2.4-174.5). The prevalence of IgG aPT was not significantly different in the thrombotic and obstetric patients, and the presence of IgM aPT antibodies was significant only in patients with thrombosis (OR, 95% CI: 2.6, 1.6-110.8). CONCLUSIONS:The study's findings confirm that IgG/IgM aPT antibodies are significantly associated with PAPS and indicate that IgG aPT antibodies are associated with clinical subsets of the disease. For the time being, however, the lower sensitivity of IgG/IgM antibodies with respect to conventional aPL antibodies precludes their inclusion in the recommendations for the diagnosis of PAP