Risks of thromboembolism associated with hormone contraceptives in Japanese compared with Western women.

We extracted 581 thromboembolic events associated with combined oral contraceptives (COC) that occurred between 2004 and 2013 in Japan, from the Pharmaceuticals and Medical Devices Agency database. The most common thromboembolic events associated with COC were deep vein thrombosis, pulmonary embolism and their combination. The reported thromboembolic events increased year by year, in association with an increase in the quantity of prescribed low-dose estrogen progestin after approval for health insurance coverage for dysmenorrhea in 2008 in Japan. The incidence of venous thromboembolism (VTE) in Japanese COC users is estimated to be lower compared with their Western counterparts. In contrast, the frequency of all thromboembolic events peaked at 90 days from the start of COC, as in Western studies. The risk of VTE in the overweight group (body mass index ≥ 25 kg/m2 ) was more than twofold higher than in the standard group, and age-specific incidence rate rose sharply after the age of 40. There were different VTE risks according to progestin type in Japan as in Western countries, but a definite conclusion about risk according to progestin type was not able to be reached at present. As for the risk of arterial embolism and thrombosis, the difference by progestin type was small, but it became higher at ≥50 years of age. Last, mortality rate caused by thromboembolism is extremely low among COC users.