Adjuvant effect of green tea intake on treatment of patients with acute venous thromboembolism

BACKGROUND: Although there have been reports that green tea intake has a thromboprophylactic effect, it was still unknown whether it had adjuvant effect on the basis of conventional anticoagulation for patients diagnosed with venous thromboembolism (VTE). METHODS: VTE patients were retrospectively classified into green tea group and no green tea group in a 1:1 ratio using propensity score matching, based on whether they drank green tea during the 3 months' period after VTE diagnosis. Primary outcomes were VTE recurrence at 3 months after VTE diagnosis and VTE-related death during 3 months after VTE diagnosis. Secondary outcomes were all-cause death and major bleeding during 3 months after VTE diagnosis. The primary and secondary outcomes were compared between the green tea and no green tea groups, in all patients, PE patients, and patients with cancer-associated VTE, respectively. RESULTS: The VTE recurrence at 3-month after VTE diagnosis occurred less in the green tea group (N = 1102) than in the no green tea group (N = 1102) (19 [1.7%] vs 55 [5.0%], P < 0.001). The VTE-related mortality during 3 months after VTE diagnosis occurred similarly between the two groups (13 [1.2%] vs 21 [1.9%], P = 0.187). The all-cause mortality (82 [7.4%] vs 78 [7.1%], P = 0.682) and major bleeding (55 [5.0%] vs 40 [3.6%], P = 0.142) during 3 months after VTE diagnosis both occurred similarly between the two groups. The results of VTE recurrence analysis in PE and cancer-associated VTE subgroups were both consistent with the main findings. CONCLUSIONS: Green tea intake on the basis of conventional anticoagulation can lead to a lower short-term VTE recurrence rate without safety concern, compared with isolated conventional anticoagulation.