Tools for practice
Tools for Practice
is proudly sponsored by the Alberta College of Family Physicians (ACFP).
ACFP is a provincial, professional voluntary organization, representing more than 3000
family physicians, family medicine residents and medical students in Alberta. Established
over fifty years ago, the ACFP strives for excellence in family practice through advocacy,
continuing medical education and primary care research.
Beginning May 2012, each Tools for Practice
is peer-reviewed, ensuring the articles
maintain a high standard of quality, accuracy, and academic integrity. TFP will be circulated
July 23, 2012
What are the Venous Thromboembolism risks with
varying Hormonal Contraception?
Clinical Question: How does the venous
thromboembolism (VT) risks compare across varying
There are no long-term randomized controlled trials which leaves cohort and case-control
• SOGC (Society of Obstetricians and Gynecologists of Canada)1 and others2 have
stated evidence regarding risk of VT with different progestins is inconclusive due to
• Some studies found no increase VT risk with drospirenone3 or transdermal patch4
• Some studies found different hormonal contraception affects VT risk:
3rd generation progestins (desogestrel, gestodene, drospirenone,
cyproterone) increase VT risk (about 2x) over 2nd generation progestins (like
Transdermal estrogen and vaginal ring increase VT risk (about 2x) over
combined oral contraceptive with levonorgesterol.8
Intrauterine device (IUD) with progestin or progestin only pills have same VT
• If these differences are real, the absolute risks per 10,000 woman years (or 1,000
women over 10 years) may be approximately:
4-5/10,000 woman years for non-users, women using progestin only pills or
10/10,000 woman years for use of OCP with levonorgestrel or
20/10,000 woman years (at most) for transdermal or vaginal ring, and OCP
with desogestrel, gestodene, drospirenone, cyproterone.7,8
29/10,000 for pregnancy (for comparison).1
• To keep the risk differences in perspective, one group estimates 2000 patients would
need to switch to lower risk combined OCP to prevent 1 VT per year.7
• Even the largest study using confirmed VT7,8 was retrospective and had potential
confounding leaving considerable uncertainty if increased risks are real.
• Other factors influencing VT risk are age (age 45-49 about 6x risk age 15-19),7
obesity (BMI 35+ about 4x risk of BMI 20-25),10 and smoking (about 2x risk).10
Bottom-line: Due to limits in the evidence, there is real uncertainty whether the
risks of VT vary with different hormonal contraceptives. If they do, the increased
risk appears to be about 1 extra VT per year for 2000 women.
Authors: G. Michael Allan MD CCFP, Sudha Koppula MD MCISc CCFP
1. Reid R, Leyland N, Wolfman W, et al. Int J Gynaecol Obstet. 2011 Mar;112(3):252-6.
2. CADTH Rapid Response. Risk of Venous Thromboembolism with Drospirenone/Ethinyl
Estradiol Combined Oral Contraceptive Pill versus Other Combined Hormone
Contraceptives: Clinical Evidence and Safety. July 11, 2011.
3. Dinger JC, Heinemann LA, Kühl-Habich D. Contraception. 2007 May; 75(5):344-54.
4. Jick SS, Kaye JA, Russmann S, et al. Contraception. 2006 Mar; 73(3):223-8.
5. Jick SS, Kaye JA, Russmann S, et al. Contraception. 2006 Jun; 73(6):566-70.
6. van Hylckama Vlieg A, Helmerhorst FM, Vandenbroucke JP, et al. BMJ. 2009 Aug 13;
7. Lidegaard O, Nielsen LH, Skovlund CW, et al. BMJ 2011;343:d6423 doi:
8. Lidegaard O, Nielsen LH, Skovlund CW, et al. BMJ 2012; 344:e2990 doi:
9. Bergendal A, Odlund V, Persson I, Kieler H. Acta Obstetricia et Gynecologica. 2009;
10. Lawrenson R, Farmer R. Contraception 2000; 62:21S-28S
Tools for Practice
is a biweekly article summarizing medical evidence with a focus on topical issues and practice
modifying information. It is coordinated by G. Michael Al an, MD, CCFP and the content is written by practising
family physicians who are joined occasional y by a health professional from another medical specialty or health
discipline. If you are not a member of the ACFP and would like to receive the TFP emails, please contact
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This communication reflects the opinion of the authors and does not necessarily mirror the perspective and policy
of the Alberta Col ege of Family Physicians.
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