Background and aims Thrombosis still remains as main cause of morbidity and mortality in SLE patients. Results from a recent study identified a strong association of anti-RNP/Sm abs+LA with thrombosis. We aimed to validate this association

Methods We studied 63 SLE patients (>4 criteria/ACR) with confirmed history of thrombosis after SLE diagnosis. As controls, 63 SLE patients without thrombosis, matched by age, gender and lupus duration were included. Disease characteristics, medication, traditional risk factors for thrombosis and thrombotic event information were retrieved from clinical files. A blood sample was drawn to determine anti-cardiolipin (IgG/IgM), antiß2-GP1 (IgG/IgM), LA, anti-RNP/Sm and anti-Sm antibodies. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) and Likelihood Ratios (LR) were calculated.

Results One hundred and twenty six SLE patients were studied. Cases and controls were similar in age, gender and disease duration (p=NS). There were no differences in the prevalence of traditional risk factor for thrombosis between cases and controls (p=NS). Among patients with thrombosis a higher frequency of anti-RNP/Sm (83% vs 62%, p<0.001), LA (62% vs 19%, p<0.001), aPL triple marker (17% vs 2%, p=0.04) and anti-RNP/Sm+AL combination (52% vs 14%, p<0.001) was observed. The combination of anti-RNP/Sm+AL showed a sensitivity 52%,specificity 86%, PPV 78% and NPV 65%, positive LR 3.67 (IC 95% 1.92–7.04) and negative LR 0.55 (IC 95% 0.42–0.74).

Conclusions This study confirmed that anti-RNP/Sm+LA association represents a risk factor for thrombosis in SLE patients. The role of anti-RNP/Sm antibodies in thrombosis deserves further studies