Background: Elevated levels of factor VIII (FVIII) have been suggested as important for the pathogenesis of venous thromboembolism (VTE). The objective of this study was to explore the association between elevated FVIII level and VTE in Japan.
Methods and results: 68 patients with objectively documented VTE and 40 controls were included. In the patients, the FVIII level was measured for a mean follow-up period of 52.6 months (3-348 months) after the onset of VTE, in order to avoid an acute-phase response. The VTE patients had a higher mean FVIII level than the controls (154.5 ± 55.8 IU/dl vs. 114.3 ± 16.0 IU/dl, P < 0.0001). According to multivariate analysis, FVIII levels above the 50(th) percentile (124 IU/dl) conferred an odds ratio of 4.9 (95% confidence intervals (CI) 1.9-12.4; P < 0.001) and those above the 75(th) percentile (150 IU/dl) conferred an odds ratio of 31.9 (95%CI 4.0-252.3; P < 0.001).
Conclusions: Elevated plasma FVIII level is a risk factors for VTE in Japanese people, and FVIII levels above the 75(th) percentile are associated with a significant odds ratio for the occurrence of VTE.