Circulating microparticles and risk of venous thromboembolism

Circulating microparticles (MPs) may trigger a hypercoagulable state, leading to thrombotic complications. Data on their association with venous thromboembolism (VTE) are few and inconsistent.

To investigate whether or not high levels of MPs are associated with an increased risk of VTE, we carried out a case-control study on 186 patients with a first, objectively diagnosed, episode of VTE and 418 healthy controls. Plasma levels of circulating MPs were measured by flow cytometry.

Patients had higher median plasma levels of total MPs than controls (2184 per μL vs 1769 per μL, p<0.0001). The risk of VTE increased progressively with increasing MPs, with a linear dose-response effect in the log odds. Individuals with MPs above the 90th percentile of the controls' distribution (P(90) = 3263 per μL) had a 5-fold increased risk of VTE than those with MPs below the 10th percentile of controls (P(10) = 913 per μL), independently of sex, age, body mass index, thrombophilia, and plasma factor VIII levels [adjusted odds ratio: 5.30 (95%CI: 2.05-13.7)]. Using the 95th percentile of controls as cut-off (P(95) = 4120 per μL), the adjusted odds ratio was 2.20 (1.01-4.79) for individuals with MPs>P(95) compared with those having MPs ≤ P(95). After exclusion of individuals with antiphospholipid antibodies and hyperhomocysteinemia, the interaction between MPs>P(95) and thrombophilia increased the VTE risk from 1.63 (0.60-4.50) to 6.09 (1.03-36.1).

High levels of circulating MPs are a possible independent risk factor for VTE.