[Analyses of the risk factors for the progression of primary antiphospholipid syndrome to systemic lupus erythematosus].

Objectives: Analyze the clinical characteristics of patients with primary antiphospholipid syndrome (PAPS) progressing to systemic lupus erythematosus (SLE).Explore the risk factors for the progression from PAPS to SLE. Methods: The clinical data of 262 patients with PAPS enrolled in Peking Union Medical College Hospital from February 2005 to September 2021 were evaluated. Assessments included demographic data, clinical manifestations, laboratory tests (serum levels of complement, anti-nuclear antibodies, anti-double-stranded DNA antibodies), treatment, and outcomes. Kaplan-Meier analysis was used to calculate the prevalence of SLE in patients with PAPS. Univariate Cox regression analysis was employed to identify the risk factors for PAPS progressing to SLE. Results: Among 262 patients with PAPS, 249 had PAPS (PAPS group) and 13 progressed to SLE (5.0%) (PAPS-SLE group). Univariate Cox regression analysis indicated that cardiac valve disease (HR=6.360), positive anti-double-stranded DNA antibodies (HR=7.203), low level of complement C3 (HR=25.715), and low level of complement C4 (HR=10.466) were risk factors for the progression of PAPS to SLE, whereas arterial thrombotic events (HR=0.109) were protective factors (P<0.05 for all). Kaplan-Meier analysis showed that the prevalence of SLE in patients suffering from PAPS with a disease course>10 years was 9%-15%. Hydroxychloroquine treatment had no effect on the occurrence of SLE in patients with PAPS (HR=0.753, 95%CI 0.231-2.450, P=0.638). Patients with≥2 risk factors had a significantly higher prevalence of SLE compared with those with no or one risk factor (13-year cumulative prevalence of SLE 48.7% vs. 0 vs. 6.2%, P<0.001 for both). Conclusions: PAPS may progress to SLE in some patients. Early onset, cardiac-valve disease, positive anti-dsDNA antibody, and low levels of complement are risk factors for the progression of PAPS to SLE (especially in patients with≥2 risk factors). Whether application of hydroxychloroquine can delay this transition has yet to be demonstrated.