Use of oral contraceptives in three European countries: a population-based multi-database study.
The use of oral contraceptives (OC) has been associated with a higher risk of venous thrombosis. In particular, third-generation and possibly also fourth-generation pills have been associated with a higher risk of venous thrombosis than second-generation progestogens. This study assessed the prevalence of OC use, user characteristics and prescribing patterns by accessing healthcare databases of three European countries. The study was commissioned and funded by the European Medicines Agency and meant to provide a basis for risk minimisation planning.
The study of OC use was performed during 2009-2010 among 2.4 million women of reproductive age in three general practice databases from the Netherlands, UK and Italy and in the PHARMO Database Network using the Out-patient Pharmacy Database and the Hospitalisation Database. Besides drug use, user and non-user characteristics were assessed.
We identified 630,000 OC users from among 2.4 million women (20-30% of women in the Netherlands and the UK and 11% of women in Italy). Mainly second-generation progestogens were prescribed in the Netherlands (nearly 80% of users); both second- (58%) and third-generation progestogens (44%) were prescribed in the UK, and mainly third-generation progestogens in Italy (62%). Most switches were to third- or fourth-generation pills. Somewhat more chronic diseases were observed among OC users, and less history of vascular disease, breast cancer or cervical cancer.
In conclusion, second-generation OC were the most frequently prescribed in the Netherlands. The prevalent use of third- or fourth-generation OC as observed in the UK and Italy suggest that more risk minimisation measures are warranted. Among OC users, a somewhat higher prevalence of chronic diseases was observed; however, information bias cannot be ruled out.
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