Associations between antiphospholipid antibodies and disease activity in Southern Chinese patients with systemic lupus erythematosus

Comprehensive research on the relationship between systemic lupus erythematosus (SLE) and antiphospholipid antibodies (aPL) in Southern Chinese patients remains limited. In this study, a retrospective cohort analysis was conducted comparing clinical data from aPL-positive and aPL-negative SLE patients. Among the 120 aPL-positive patients, the positivity rates for specific antibodies were as follows: 40.8% for aCL-IgG, 7.1% for aCL-IgM, 3.4% for aCL-IgA, 27.7% for β2GPI-IgG, and 21.0% for LAC. SLEDAI-2K scores were significantly higher in the aPL-positive group than in the negative controls (p < 0.0001). Additionally, aPL-positive patients exhibited reduced C3 and C4 levels alongside elevated dsDNA antibodies, circulating immune complexes (CIC), and IgM (p < 0.05). Notably, positivity for aCL-IgG, β2GPI-IgG, and LAC showed significant positive correlations with SLEDAI-2K scores (p < 0.01). The positive group also had a significantly higher SLICC/ACR Damage Index (SDI) (p = 0.033) and incidence of thrombotic events (p = 0.046). Multi-organ involvement was more extensive in aPL-positive than in aPL-negative patients (p = 0.004), with distinct organ involvement patterns observed across different aPL subtypes. In conclusion, patients with active SLE and aPL-positivity demonstrated significantly elevated disease activity and more extensive multi-organ involvement compared to their aPL-negative counterparts.