Thrombosis in Systemic Lupus Erythematosus and Other Autoimmune Diseases of Recent Onset

Objective: To determine the risk of thrombosis in patients with systemic lupus erythematosus (SLE) and other autoimmune diseases of recent onset.

Methods: A retrospective cohort of 482 patients, mean age 28.3 years, with SLE or other autoimmune diseases was analyzed. Followup started at diagnosis or first appointment within 12 months since diagnosis until the development of thrombosis, end of study, loss to followup, or death. Thromboses were diagnosed upon clinical manifestations and confirmed by appropriate studies. Clinical variables were retrieved from the medical records, and SLE activity was assessed from the medical notes at onset of thrombosis, or at a dummy date for thrombosis, using the SLE Disease Activity Index-2K.

Results: During 2936 patient-years of followup, thromboses occurred in 49 patients (20.3%) with SLE and 6 patients (2.5%) with other autoimmune diseases. The incidence rate of thrombosis was 36.3 and 3.8 per 1000 patient-years in SLE and in other autoimmune diseases, respectively; relative risk 9.6 (95% CI 4.1-27.4, p<0.0001). Throughout the disease course, the risk of thrombosis remained high in the SLE group, while in patients with other autoimmune diseases this risk was lower. The incidence of venous and arterial thrombosis was similar among SLE patients and patients with other autoimmune diseases. SLE and venous insufficiency were associated with thromboses in the total study population, and with venous insufficiency, vasculitis, and disease activity in the SLE group.

Conclusion: Patients with autoimmune diseases, particularly SLE, are at an increased risk of thrombosis. In patients with SLE, the risk remains elevated throughout the course of the disease.