Risk of thromboembolism in women taking ethinylestradiol/drospirenone and other oral contraceptives

Obstet Gynecol. 2007 Sep;110(3):587-93. doi: 10.1097/01.AOG.0000279448.62221.a8.


Objective: The oral contraceptive ethinylestradiol 0.03 mg/drospirenone 3 mg contains a progestin component that differs from other oral contraceptives. Case reports and prescription event monitoring suggested that ethinylestradiol/drospirenone might be associated with an elevated risk of thromboembolism. We sought to estimate the association between ethinylestradiol/drospirenone and risk of thromboembolism relative to the association among other oral contraceptives.

Methods: We identified ethinylestradiol/drospirenone initiators and a twofold larger group of other oral contraceptive initiators between June 2001 and June 2004 within a U.S. health insurer database. The comparison group was selected to have demographic and health care characteristics preceding oral contraceptive initiation that were similar to ethinylestradiol/drospirenone initiators. Thromboembolism during the follow-up of the cohorts was identified through claims for medical services, and only medical record-confirmed cases were included in analyses. The primary (as-matched) analysis used proportional hazards regression, whereas a secondary (as-treated) analysis accounted for changes in oral contraceptives during follow-up using Poisson regression.

Results: The 22,429 ethinylestradiol/drospirenone initiators and 44,858 other oral contraceptive initiators were followed for an average of 7.6 months, and there were 18 cases of thromboembolism in ethinylestradiol/drospirenone initiators and 39 in the comparators (rate ratio 0.9, 95% confidence interval 0.5-1.6). More than 9,000 women would need to be prescribed oral contraceptives to observe a difference of one case of thromboembolism. Results of the as-treated analysis were similar to those of the as-matched analysis.

Conclusion: Ethinylestradiol/drospirenone initiators and initiators of other oral contraceptives are similarly likely to experience thromboembolism.

Level of evidence: II.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Androstenes / administration & dosage
  • Androstenes / adverse effects*
  • Child
  • Cohort Studies
  • Contraceptives, Oral, Combined / administration & dosage
  • Contraceptives, Oral, Combined / adverse effects*
  • Ethinyl Estradiol / administration & dosage
  • Ethinyl Estradiol / adverse effects*
  • Female
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Proportional Hazards Models
  • Risk Assessment
  • Risk Factors
  • Thromboembolism / chemically induced*
  • Thromboembolism / epidemiology


  • Androstenes
  • Contraceptives, Oral, Combined
  • Ethinyl Estradiol
  • drospirenone