Background and aims To identify the prevalence of positive antiphospholipid antibodies (aPL) and related clinical characteristics in Korean SLE patients

Methods Among 505 SLE patients from KORean lupus NETwork (KORNET), we selected 469 patients who underwent aPL tests within 2 years of enrollment. They were classified into two groups: 1) aPL (+) group as patients with at least one positive aPL which includes IgG anticardiolipin antibody (aCL >40 GPLU/ml), IgG anti-ß2 glycoprotein I (anti- ß2GPI >40 SGU/ml) and lupus anticoagulant (LAC), and 2) aPL (-) groups as patients with negative aPL. We compared the demographic and clinical characteristics between two groups, and clinical symptoms of thrombosis and obstetric complications were compared according to aPL positivity.

Results The 49 (10.4%) SLE patient had at least one positive aPL, and all 3 aPL were positive in 1 patient (0.2%). Although age, sex, autoantibody profile, and the SELENA SLEDAI score were not different between two groups, the SLICC/ACR damage index was higher in aPL (+) group (p=0.03), and 57.1% of aPL (+) patients were using aspirin. More patients in aPL (+) group underwent cerebrovascular disease (CVD) (<0.01), whereas no statistical difference was found in history of ischaemic heart disease or spontaneous abortion. Moreover, renal failure was higher in aPL (+) group (p<0.01), while lupus nephritis was comparable between two groups (p=0.70).

Conclusions Ten percent of patients had positive aPL in Korean SLE patients. In addition, CVD and renal failure were more common in patients with aPL (+) SLE patients.