Published: June 2002

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POPs: An Option Post-VTE

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Prescriber Update 23(2): 22-23
June 2002

Medsafe Editorial Team

The Medicines Adverse Reactions Committee advises that progestogen-only oral contraceptives (progestogen-only pills; POPs) can be considered as an option for women who have previously experienced venous thromboembolism (VTE).  POPs are contraindicated in the presence of a current thromboembolic process.  This advice is in line with recent WHO guidelines and published studies.

History of VTE not a contraindication for POPs

The Medicines Adverse Reactions Committee (MARC) advises that the current evidence supports considering progestogen-only oral contraceptives (progestogen-only pills; POPs*) as an option in women with a history of deep vein thrombosis (DVT) or pulmonary embolism (PE), provided the thromboembolic process has resolved.  This advice applies even if the thrombotic event occurred with a combined oral contraceptive.

Advice consistent with WHO guidelines

Guidelines¹ released by the WHO (World Health Organisation) in 2000 advocate that for most women with a family or personal history of DVT or PE the benefits of using a POP outweigh the risks, and a POP can generally be used.  The guideline also advises that the use of a POP is not recommended in the presence of current venous thromboembolism (VTE) unless other methods are not available or are unacceptable.  However, the MARC considers that POPs are an absolute contraindication in women with a current thromboembolic process.  The WHO guidelines make no distinction between minor and major surgery, and recommend that POPs can continue to be used for women undergoing any surgical procedure.  Where there is prolonged immobilisation following surgery, the guidelines advise that it is generally appropriate to continue POP use.  Based on this advice, the MARC suggests that when determining the most appropriate oral contraceptive, a POP may also be considered for women with other risk factors that put them at a high risk of VTE with a combined oral contraceptive, especially for those with more than one risk factor (e.g. family history and BMI > 30).

Only one recent case of VTE with a POP in CARM database

Since 1990, the Centre for Adverse Reactions Monitoring (CARM) has received only one report of VTE with a POP.  This was a nonfatal PE in a woman taking the POP, ethynodiol.  The woman was obese and the PE developed following severe anaphylaxis due to general anaesthesia.  Because of the presence of risk factors for VTE, the use of the POP may not have contributed to the event.

This single New Zealand case of VTE with POPs compares with 32 cases of PE and 48 of other venous thrombotic events with the combined oral contraceptives in the period from February 1996 to December 2001.

Case-control studies find no increase in risk of VTE with POPs

Three case-control studies^2-4 have examined the risk of VTE with POPs.  None found that use of POPs was associated with a significantly elevated risk of VTE.  Each of the studies had small case numbers, but one² conducted by the WHO included 21 cases.

With higher doses of progestogens used for non-contraceptive purposes (daily dose 5-30mg compared with 0.03-0.5mg for contraception), Vasilakis et al³ and the authors⁵ of the WHO study found the risk of VTE increased.  These studies also involved small case numbers.

While all results indicate a need for further studies, at the doses routinely used for contraception, current evidence suggests that there is little or no increase in risk of VTE with POPs.  There may be an elevation in risk with higher dose progestogens.  Any new information that becomes available on this topic will be reviewed by the MARC, and prescribers will be advised, if necessary.

* POPs approved in New Zealand are Cerazette, Femulen, Microlut, Microval and Noriday.

Competing interests (authors): none declared.

References

1. Improving access to quality care in family planning. Medical eligibility criteria for contraceptive use. Second edition. World Health Organisation, Geneva, 2000.
2. WHO Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception. Cardiovascular disease and use of oral and injectable progestogen-only contraceptives and combined injectable contraceptives: results of an international, multicenter, case-control study. Contraception 1998;57:315-24.
3. Vasilakis C, Jick H, del Mar Melero-Montes M. Risk of idiopathic venous thromboembolism in users of progestogens alone. Lancet 1999;354:1610-1611.
4. Heinemann LA, Assmann A, DoMinh T, et al. Oral progestogen-only contraceptives and cardiovascular risk: results from the Transnational Study on Oral Contraceptives and the Health of Young Women. Europ J Contraception & Reproductive Health Care 1999;4:67-73.
5. Poulter NR, Chang CL, Farley TMM, et al. Risk of cardiovascular diseases associated with oral progestogen preparations with therapeutic indications. Lancet 1999;354:1610.