Full Length ArticleRisks of thromboembolism associated with hormonal contraceptives related to body mass index and aging in Japanese women

- Risk of VTE in the obesity group was more than 2 times higher than in the standard group.
- Age-specific incidence rates of VTE were found to rise sharply after the age of 40.
- Risk of VTE of the fourth-generation COC was higher even in Japanese.
- Risk of ATE became higher at over 50 years of age with no relation to progestin type.

ObjectiveThe aim of this study is to estimate the risk of thromboembolism related to body mass index (BMI) and aging among users of hormonal contraceptives in Japan.MethodsA case-control study of the risk of obesity and a descriptive study of the risk of age were conducted. We used the Pharmaceuticals and Medical Devices Agency database, and extracted thromboembolic events of combined oral contraceptive (COC) products. Control data were from the National Health and Nutrition Survey in Japan. Denominator of descriptive study was from IMS Health, JPM.ResultsA total of 306 thromboembolic events and 6423 controls were analyzed. The odds ratios (95% confidence interval) of the obesity groups (BMI ≥ 25) were 2.32 (1.71-3.15) for venous thromboembolism (VTE), 1.16 (0.62-2.18) for arterial embolism and thrombosis (ATE), and 1.83 (1.38-2.43) for overall thromboembolic events compared with the standard group (BMI of 18.5-24.9) as a reference. The estimated incidence rates of VTE, ATE and overall thromboembolic events per 10,000 person-years in users of therapeutic remedies for dysmenorrhea (35 μg ethinylestradiol combined with norethisterone, 20 μg ethinylestradiol combined with drospirenone and dienogest) among women aged 10-59 years from 2009 to 2013 were 2.38 (2.08-2.74), 0.63 (0.48-0.82), and 3.17 (2.81-3.57), respectively. This tendency was not seen for dienogest.ConclusionsThe risk of VTE in the obesity group among COC users was more than 2 times higher than in the standard group. The incidence rates of VTE in Japanese users of all remedies for dysmenorrhea except dienogest were as high as in people in Western countries.