Venous thromboembolism in patients with SLE: long-term incidence, risk factors, and outcomes

Patients with systemic lupus erythematosus (SLE) experience susceptibility to thrombotic events due to chronic inflammation, vascular damage, and acquired coagulation disorders resulting from antiphospholipid antibodies (aPL).

Nossent et al. recently published an article in Lupus, comparing the incidence rates (IRs), risk factors, and outcomes of a first venous thromboembolic event (VTE) between patients with SLE and controls. Here, we summarize their key findings.

Methods

• This observational study retrospectively analyzed prospectively collected data from the Western Australia Rheumatic Disease Epidemiological Registry (WARDER) from the period 1985–2015.
• Patients diagnosed with SLE were compared with matched hospitalized controls.
• Primary outcomes were IRs of VTE per 1,000 person-years.
• Secondary outcomes were recurrence of VTE (defined as any new VTE event in >90 days post first VTE event), pulmonary hypertension, and death.

Key findings

• A total of 1,854 patients with SLE (median age: 40 years; females: 86%) and 12,107 matched hospitalized controls (median age: 40 years; females: 88.6%) were assessed.
• The odds for a first VTE were significantly higher in patients with SLE vs controls (12.8% vs 3.3%; odds ratio: 4.26). The IRs for VTE, pulmonary embolism (PE), and venous thrombosis (VT) were higher for patients with SLE than in controls (Figure 1).
  • The time between index admission and first VTE was shorter in patients with SLE vs controls (35 vs 144 months; p < 0.01).
  • Across three decades (1985–2015), there was a decline in overall IR of VTE among patients with SLE, primarily due to significant decreases in PE IRs (R²: 0.99; p < 0.01) while VT IRs did not change significantly in both groups.
• Recurrences of VTE were more frequent in patients with SLE than in controls (24.1% vs 10.2%; p < 0.01).
  • The median time to first recurrence was 15 months in patients with SLE and 23 months in controls (p = 0.36).
• The major risk factors for VTE included aPL, serositis, lupus nephritis, and thrombocytopenia (Figure 2A).
  • Arterial hypertension, trauma/immobility, smoking, and obesity were independent risk factors for VTE, with risk estimates largely comparable between patients with SLE and controls.
• The occurrence of VTE was not associated with arterial thrombotic events, however, was associated with an increased risk of pulmonary hypertension and death in both groups after 10 years of follow-up (p < 0.01; Figure 2B).
  • The hazard for pulmonary hypertension and death were higher in both groups for patients experiencing PE, but not among those experiencing VT.

Figure 1. Incidence rates per 1,000 person-years for VTE, PE, and VT in patients with SLE vs controls* 

PE, pulmonary embolism; VT, venous thrombosis; VTE, venous thromboembolic event, SLE, systemic lupus erythematosus
 *Data from Nossent , et al.¹

Figure 2. Adjusted hazard ratio for association between A risk factors and a first VTE and B death and arterial events following first VTE in patients with SLE vs controls*  

aHR, adjusted hazard ratio; CI, confidence interval; SLE, systemic lupus erythematosus.
*Data from Nossent, et al.¹