Antiphospholipid patterns predict risk of thrombosis in systemic lupus erythematosus

OBJECTIVE

We evaluated which aPL combinations increase the risk of future thrombosis in patients with SLE.

METHODS

This prospective cohort study consisted of SLE patients who had been tested for all seven aPL (LA, aCL isotypes IgM, IgG and IgA, and anti-β2-glycoprotein I isotypes IgM, IgG and IgA). Pooled logistic regression was used to assess the relationship between aPL and thrombosis.

RESULTS

There were 821 SLE patients with a total of 75 048 person-months of follow-up. During the follow-up we observed 88 incident cases of thrombosis: 48 patients with arterial, 37 with venous and 3 with both arterial and venous thrombosis. In individual models, LA was the most predictive of any [age-adjusted rate ratio 3.56 (95% CI 2.01, 6.30), P < 0.0001], venous [4.89 (2.25, 10.64), P < 0.0001] and arterial [3.14 (1.41, 6.97), P = 0.005] thrombosis. Anti-β2-glycoprotein I IgA positivity was a significant risk factor for any [2.00 (1.22, 3.3), P = 0.0065] and venous [2.8 (1.42, 5.51), P = 0.0029] thrombosis. Only anti-β2-glycoprotein I IgA appeared to add significant risk to any [1.73 (1.04, 2.88), P = 0.0362] and venous [2.27 (1.13, 4.59), P = 0.0218] thrombosis among those with LA. We created an interaction model with four categories based on combinations of LA and other aPL to look at the relationships between combinations and the risk of thrombosis. In this model LA remained the best predictor of thrombosis.

CONCLUSION

Our study demonstrated that in SLE, LA remained the best predictor of thrombosis and adding additional aPL did not add to the risk, with the exception of anti-β2-glycoprotein I IgA.

Anti-vimentin/cardiolipin IgA in the anti-phospholipid syndrome: A new tool for 'seronegative' diagnosis

Anti-phospholipid syndrome (APS) is a systemic autoimmune disorder defined by the simultaneous presence of vascular clinical events, pregnancy morbidity and anti-phospholipid antibodies (aPL). In clinical practice, it is possible to find patients with APS who are persistently negative for the routine aPL tests (seronegative APS; SN-APS). Recently, the identification of aPL immunoglobulin (Ig)A and/or anti-β2-glycoprotein-I (β2-GPI) IgA was shown to represent a further test in SN-APS patients. In this study we analyzed the presence of anti-vimentin/cardiolipin (aVim/CL) IgA in a large cohort of patients with SN-APS, evaluating their possible association with clinical manifestations of the syndrome. This study includes 60 consecutive SN-APS patients, 30 patients with APS and 40 healthy donors. aVim/CL IgA were detected by enzyme-linked immunosorbent assay (ELISA). Results show that 12 of 30 APS patients (40%) and 16 of 60 SN-APS patients (26.7%) resulted positive for aVim/CL IgA. Interestingly, SN-APS patients who tested positive for aVim/CL IgA showed a higher prevalence of arterial thrombosis (p = 0.017, likelihood positive ratio = 5.7). This study demonstrates for the first time, to our knowledge, the presence of aVim/CL IgA in sera of patients with APS. In particular, they revealed a potential usefulness in identification of a significant proportion of SN-APS patients. Moreover, as patients tested positive for aVim/CL IgA reported a high likelihood ratio to have the clinical features of APS, this test may be considered a suitable approach in the clinical evaluation of SN-APS.

"Non-criteria" antiphospholipid antibodies add value to antiphospholipid syndrome diagnoses in a large Chinese cohort

BACKGROUND

Despite expansion in the 2006 Sydney antiphospholipid syndrome (APS) classification criteria to include IgG/IgM anti-β2-glycoprotein (aβ2GPI) antibodies in addition to IgG/IgM anti-cardiolipin antibodies (aCL) and lupus anticoagulant (LAC), some individuals with clinical features of APS remain seronegative (seronegative APS or SNAPS) and are at risk of recurrent thrombosis and pregnancy morbidities. Our aim was to assess the value of "non-criteria" aPL antibodies to detect these SNAPS patients.

METHODS

One hundred ninety-two APS patients, 90 SNAPS patients, 193 autoimmune disease controls, and 120 healthy controls were evaluated. Ten antiphospholipid antibodies (aPLs) were tested using commercial kits, including 5 non-criteria aPLs: anti-phosphatidylserine/prothrombin antibodies (aPS/PT) IgG/IgM, aCL IgA, aβ2GPI IgA, and anti-β2GPI Domain 1 (aβ2GPI-D1) IgG.

RESULTS

Up to 60.9% of the SNAPS and 93.5% of APS patients were detected by at least one non-criteria aPL. aPS/PT IgG had the highest Youden index in classifying APS and SNAPS from controls. aPS/PT IgG and aβ2GPI Domain 1 IgG seem to be the most significant risk factors for thrombotic events and pregnancy morbidity, respectively. aPS/PT IgG/IgM and aβ2GPI-D1 IgG were detected in some SNAPS patients, while IgA isotypes of aCL/aβ2GPI tended to appear together with other biomarkers. The combined analysis showed enhanced diagnostic performance with the inclusion of non-criteria aPLs.

CONCLUSIONS

Recognition of SNAPS patients is critical for clinical management and prevention of potential thrombotic and obstetric adverse events. The non-criteria antiphospholipid antibodies help to identify a considerable portion (60.9%) of these patients who otherwise may remain untreated and at clinical risk.