R.D.T. Farmer, R.A. Lawrenson, et al (European Institute of Health and Medical Sciences, University of Surrey, Guildford, Department of Epidemiology and Population Health, Cancer and Public Health Unit, London School of Hygiene and Tropical Medicine, London.
A Comparison of the risks of venous thromboembolic disease in association with different combined oral contraceptives.
Br. J.Clin. Pharmacol.49(6),June 2000, 580-590.
In October 1995, in response to the results of 3 studies the committee on the safety of medicines advised doctors and pharmacists that Ocs containing desogestrel (DSG) and gestodene (GST) were associated with around 2 fold increase in the risk of thromboembolism compared with those containing other progestogens. Objective of present study was to estimate the risk of idiopathic venous thromboembolic disease (VTE) in users of combined Ocs (COC), to compare the risk between formulations. The method used was, a case-control study using the General Practice Research Database. Women with VTE event recorded between 1992 and 1997, who were treated with an anticoagulant, were likely to have been using a COC on the day of the event and had no exclusion factors, were deemed cases.
The authors found a significant association between idiopathic VTE and current smoking, BMI over 35, and asthma and general ill-health (indicated by number of prescriptions issued). The results of this study indicate that a number of characteristics of the women taking COCs affect the risk of VTE.
There is no evidence to support the hypothesis that there is any difference in risk between COC formulations containing under 50 micro-gm ethinyloestradiol.