Venous thromboembolism in southern Chinese patients with systemic lupus erythematosus

The objective is to study the annual incidence and standardized incidence ratio (SIR) of venous thromboembolism (VTE) in a cohort of Chinese patients with systemic lupus erythematosus (SLE). VTE events of SLE patients occurring between 1999 and 2008 were identified from our database, and the annual incidence of VTE was calculated according to the cohort size. SIRs were estimated by the ratios of the incidence of VTE in SLE to the general population. In 2008, 516 SLE patients were in our cohort. The mean age of SLE onset was 32.2 +/- 14 years and the duration of SLE was 9.3 +/- 8.8 years. Fifty-seven percent of the patients had disease duration of > or =5 years. Between 1999 and 2008, 18 episodes of VTE occurred in 14 patients. The incidence of VTE did not show significant fluctuation and the mean annual incidence was 4.2/1,000 patient-year. The reported VTE events were: popliteal vein thrombosis (56%), pulmonary embolism (22%), renal vein, retinal vein, subclavian vein and dural sinus thrombosis (5.6% each). The cumulative risks of VTE since SLE diagnosis were 2.8% and 3.7% at 5 and 10 years, respectively. Compared to the general population, the mean SIR of VTE in SLE patients within this period was 11.9 (7.31-19.6; p < 0.001). The SIR of VTE was highest in patients under the age of 30 years. The presence of the antiphospholipid antibody was independently associated with VTE (HR 4.36 [1.67-11.4]; p = 0.003). Although venous thrombosis is uncommon in Chinese, Chinese patients with SLE are 12 times more prone to VTE than the general population.