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Third generation oral contraception and venous thromboembolism

The published evidence confirms the Committee on Safety of Medicine's concerns

Eighteen weeks ago, Britain's Committee on Safety of Medicines raised concerns about the newest brands of oral contraceptive pill,1 responding to new evidence that pills containing desogestral and gestodene conferred a two times greater risk of venous thromboembolism than pills containing other progestagens. At the time, none of the data on which the committee's announcement was based had been published. Dissatisfied doctors, anxious patients, and hundreds of column inches in the press were the natural consequence of this imposed uncertainty.2 Data from three case control studies, one of them nested in a cohort study, have since been published,3 4 5 6 and this week's BMJ carries two papers reporting data from a third case control study (pp 83, 88).7 8

The studies published in December were a subanalysis of data from the large WHO study of women in 10 countries exposed to third generation oral contraceptive pills3 4; a casecontrol study of current users of the oral contraceptive pill from the British general practice research database5; and a reanalysis of the Leiden thrombophilia study.6 All studies indicated a statistically significant doubling of the adjusted odds ratios for …