Long-term incidence, risk factors and complications for venous thromboembolism in patients with systemic lupus erythematosus

To compare frequency, incidence rates (IR), risk factors and outcomes of a first venous thromboembolic event (VTE) between patients with systemic lupus erythematosus (SLE) and controls.

Using state-wide longitudinal hospital data from Western Australia (WA), we recorded venous thrombosis (VT) and pulmonary embolism (PE) in patients with SLE (n = 1854, median age 40, 86% female) and matched hospitalised controls (n = 12,107, median age 40 years, females 88.6%) in the period 1985–2015. Results presented are medians, frequency, IR per 1000 person years (PY) and odds, rate, or adjusted hazard ratios (OR/RR/a-HR) with 95% confidence intervals (CI).

Patients with SLE had significantly higher odds (12.8 vs 3.3%; OR 4.26, CI 3.60–5.05) and IR for a first VTE (10.09 vs 1.52; RR 6.64; CI 5.56–7.79). Over the three study decades, the IR for PE declined in patients with SLE from 7.74 to 3.75/1000 PY (p < .01) with no changes observed for VT or in controls. VTE recurred more frequently in patients with SLE (24.1% vs 10.2 %) (p < .01). Antiphospholipid antibodies (aPL) (a-HR 4.24, CI 2.50–7.19), serositis (a-HR 2.70, CI 1.86–3.91), lupus nephritis (a-HR 1.75 CI 1.25–2.33) and thrombocytopenia (a-HR 1.65 (1.10–2.49) were the strongest disease risk factors for VTE only in patients with SLE, while arterial hypertension, smoking and obesity were independent VTE risk factors for both groups. VTE was not associated with an increased risk for arterial events, but PE increased the risk for pulmonary hypertension (PH) in both patients with SLE (a-HR 6.47, CI 3.73–11.23) and controls (a-HR 9.09, CI 3.50–23.63). VTE increased the risk of death in both patients with SLE (a-HR 2.02, CI 1.50–2.70) and controls (a-HR 6.63, CI 5.21–8.42) after 10 years of follow-up.

VTE affected 12.8% of patients with SLE at six times the VTE rate in controls with aPL as the strongest, but not the only risk factor in SLE. The risk of PH was increased in both groups following PE, but VTE did not associate with an increased risk of arterial events.