Plasma homocysteine and the risk of venous thromboembolism: insights from the FIELD study

Background: The lipid-lowering effect of fenofibrate is accompanied by a rise in plasma homocysteine (HCY), a potential risk factor for venous thromboembolism (VTE). This study investigated the relationship between HCY and the risk of VTE in patients treated with fenofibrate. Methods: The relationship between HCY and deep-vein thrombosis or pulmonary embolism was investigated in 9522 participants of the 5-year Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial. All subjects received fenofibrate during a 6-week active run-in phase before randomization. A Cox proportional-hazards model was used to assess the effect of HCY on risk of venous thromboembolic events. Results: During active-drug run-in, HCY rose on average by 6.5 μmol/L, accompanied by a substantial rise in plasma creatinine (+12%). Fenofibrate-induced changes in HCY and creatinine were fully reversible in the placebo group but persisted in the treatment group until reversing at the end of therapy. During follow-up, 1.8% had at least one episode of deep-vein thrombosis or pulmonary embolism: 103 on fenofibrate and 68 on placebo (log-rank p=0.006). In multivariate analysis, every 5 μmol/L higher baseline HCY was associated with 19% higher risk of VTE. Fenofibrate treatment was associated with 52% higher risk, but the change in HCY with fenofibrate was not significantly associated with VTE after adjustment for baseline HCY. Conclusions: Hyperhomocysteinemia is prospectively associated with VTE. Fenofibrate may predispose individuals with high pretreatment HCY towards VTE. The fenofibrate-induced increase in HCY did not, however, explain the risk associated with fenofibrate therapy.