Oral contraceptive oestrogen and progestin potencies and the incidence of deep venous thromboembolism
Gerstman, B.B.; Piper, J.M.; Freiman, J.P.; Tomita, D.K.; Kennedy, D.L.; Ferguson, W.J.; Bennett, R.C.
International Journal of Epidemiology 19(4): 931-936
1990
ISSN/ISBN: 0300-5771 PMID: 2084024 DOI: 10.1093/ije/19.4.931Document Number: 375741
To assess possible differences in the incidence of venous thrombosis and pulmonary embolism associated with oral contraceptives of varying hormonal potencies, the authors conducted a retrospective cohort study in the 15-44 year old Michigan Medicaid population. Cohorts were defined by the progestin- and estrogen-potencies of oral contraceptives in use at the time of follow-up as classified by an oral contraceptive potency scheme. Using the low-estrogen- low-progestin-potency formulations for reference (rate ratio = 1), adjusted rate ratios of 0.8 (95% Cl: 0.5 to 1.3, P = 0.41) and 0.6 (95% Cl 0.4 to 1.2, P = 0.13) were observed for intermediate-progestin-potency and high-progestin-potency formulations, respectively. Adjusted rate ratios of 1.4 (95% Cl: 0.8 to 2.3 P = 0.21) and 2.6 (95% Cl: 1.2 to 5.5, P = 0.01) were observed for intermediate- and high-estrogen-potency formulations. These data suggest a dose-response relationship between oral contraceptive estrogen potency and venous thromboembolism, whereas no such evidence for a dose-response relationship between oral contraceptive progestin potency and venous thromboembolism was found.