Third generation oral contraceptives and risk of venous thromboembolic disorders: an international case-control study. Transnational Research Group on Oral Contraceptives and the Health of Young Women.
OBJECTIVE
To test whether use of combined oral contraceptives containing third generation progestogens is associated with altered risk of venous thromboembolism.


METHODS
Matched case-control study.


METHODS
10 centres in Germany and United Kingdom.


METHODS
Cases were 471 women aged 16-44 who had a venous thromboembolism. Controls were 1772 women (at least 3 controls per case) unaffected by venous thromboembolism who were matched with corresponding case for age and for hospital or community setting.


METHODS
Odds ratios derived with stratified analyses and unconditional logistic regression to adjust for potential confounding variables.


RESULTS
Odds ratios (95% confidence intervals) for venous thromboembolism were: for any oral contraceptives versus no use, 4.0 (3.1 to 5.3); for second generation products (low dose ethinyl-oestradiol, no gestodene or desogestrel) versus no use, 3.2 (2.3 to 4.3); for third generation products (low dose ethinyloestradiol, gestodene or desogestrel) versus no use, 4.8 (3.4 to 6.7); for third generation products versus second generation products, 1.5 (1.1 to 2.1); for products containing gestodene versus second generation products, 1.5 (1.0 to 2.2); and for products containing desogestrel versus second generation products, 1.5 (1.1 to 2.2). Probability of death due to venous thromboembolism for women using third generation products is about 20 per million users per year, for women using second generation products it is about 14 per million users per year, and for non-users it is five per million per year.


CONCLUSIONS
Risk of venous thromboembolism was slightly increased in users of third generation oral contraceptives compared with users of second generation products.
Spitzer
W O
WO
Department of Epidemiology and Biostatistics, McGill University, Montreal, Canada.
Lewis
M A
MA
Heinemann
L A
LA
Thorogood
M
M
MacRae
K D
KD
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003277:Contraceptives, Oral, Combined / Q000009:adverse effects*; D003280:Contraceptives, Oral, Synthetic / Q000009:adverse effects*; D017135:Desogestrel / Q000009:adverse effects; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D009652:Norpregnenes / Q000009:adverse effects; D016017:Odds Ratio; D012307:Risk Factors; D013923:Thromboembolism / Q000139:chemically induced* / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology
D003277:Contraceptives, Oral, Combined; D003280:Contraceptives, Oral, Synthetic; D009652:Norpregnenes; C033273:Gestodene; D017135:Desogestrel