SAN FRANCISCO, CA—Patients with systemic lupus erythematosus (SLE) who currently use prednisone at a dose >20mg are at increased risk of both arterial and venous thrombosis, investigators concluded at the 2015 ACR/ARHP Annual Meeting.

Although studies have investigated factors associated with thrombosis in SLE, “few have examined risk factors specific for venous thrombosis in patients with SLE and no study to date has compared the relative influence of risk factors on venous versus arterial thrombosis prospectively,” noted Katharine Hickman, of the University College London, London, United Kingdom, and colleagues.

The investigators examined the effect of traditional and disease-specific risk factors on venous and arterial thrombosis using data from 1,951 patients enrolled in a prospective cohort from April 1987 to September 2014. A total of 189 thrombotic events were observed in 12,638 person years of follow-up.

“We fit separate multivariable models for venous and arterial thrombosis that included variables that were most important based on the age-adjusted and preliminary regression models,” she explained.

Independent variables associated with venous thrombosis were recent systolic blood pressure >140mmHg (risk ratio [RR] 1.9 (95% confidence internal [CI]; 1.2, 3.1; P=0.01; diabetes (RR 2.5; 95% CI: 1.5, 4.0; P=0.002), history of low complement component C3 (RR 2.0; 95% CI: 1.1, 3.4; P=0.020); history of lupus anticoagulant (RR 1.6; 95% CI: 1.0, 2.6; P=0.036); and current prednisone treatment 1–9mg/day (RR 1.3; 95% CI: 0.7, 2.4; P=0.35); 10–19mg/day (RR 1.9; 95% CI: 1.0, 3.6; P=0.04) and >20mg/day (RR 3.3; 95% CI: 1.6, 6.5; P=0.0008).

For arterial thrombosis, the independent variables identified were recent systolic blood pressure >140mmHg (risk ratio [RR] 1.6 (95% confidence internal [CI]; 1.1, 2.4; P=0.028; diabetes (RR 1.9; 95% CI: 1.2, 2.9; P=0.0034), recent low C3 (RR 1.7; 95% CI: 1.1, 2.5; P=0.0201); and current prednisone treatment 1–9mg/day (RR 1.8; 95% CI: 1.1, 3.0; P=0.019); 10–19mg/day (RR 3.1; 95% CI: 1.9, 5.2; P<0.0001) and >20mg/day (RR 6.4; 95% CI: 3.7, 11.3; P<0.0001).

“Even after controlling for all the other variables in the model, there was a strong association between recent systolic blood pressure, diabetes, and current prednisone dose on both venous and arterial thrombosis,” Dr. Hickman reported.

A recent elevated cholesterol level was an independent risk factor for venous but not arterial thrombosis, while current hydroxychloroquine use was protective only against venous thrombosis.