An article was published on one of my all-time favorite topics recently in Headache: the risk of stroke in women with migraine who take oral contraceptives (see PubMed abstract here: https://www.ncbi.nlm.nih.gov/pubmed/29139115). I blogged on this topic back in April as part of my Migraine Gender Gap series. I feel strongly about this because so many women find relief by using oral contraceptives or other forms of hormone therapy to combat their menstrual migraines; yet current World Health Organization (WHO) and American Congress of Obstetricians and Gynecologists (ACOG) guidelines list history of migraine with aura as an absolute contraindication to prescribing combined hormonal contraceptives. I read every new paper or commentary on this subject because I feel that more research in this area is crucial to the well-being of women with migraines.

BACKGROUND: Previous reports have shown that the risk of stroke is about twice as high in women with migraine as it is in women who do not experience migraines, most of this association is due to a high risk in women who experience migraine with aura. A higher risk has been reported for both ischemic and hemorrhagic stroke.

The authors of the current study (Sheikh et. al.) conducted a systematic review of 15 studies on ischemic or hemorrhagic stroke in women using estrogen-containing contraception, 11 of which were case-control studies. Study quality was assessed to be good; however received lower marks than it would have if it were reviewing studies where treatment groups were assigned instead of merely observed.

HYPOTHESIS: Lower dose (newer) CHC formulations are associated with less increase in stroke risk compared to higher dose (older) formulations in women with migraine.

CONCLUSIONS:

  • The authors confirmed results from previous studies that showed an increase in stroke in women with migraine taking CHC’s with doses greater than 50mg EE.
    • However, most currently used CHC preparations do not have doses this high. Since most studies did not indicate the estrogen doses used by patients enrolled, insufficient evidence was found to determine whether stroke risk is also increased in lower dose formulations.
      • Current formulations range between 30-40mg EE, or 20mg for low dose formulations.
    • The authors looked for an interaction effect between the variables of interest and did not find one. In other words, the risk of stroke in a woman with migraine who uses CHC might only be due to the increased stroke risk associated with migraine and the risk associated with the use of CHC.

MY TWO CENTS:

What I find most interesting about studies that cannot prove an association between current low-dose CHC’s and increased stroke risk in women with migraine is that there is some evidence that higher incidence of migraine with aura may be associated with increased stroke risk. (The authors of this study also allude to this.) Therefore, women who use CHC’s to decrease the frequency of their menstrual migraines could theoretically be decreasing their stroke risk; yet they are often denied CHC’s due to current guidelines. It is for this reason that I feel further research in this area is so important, and I applaud this review.

I give this article a thumbs up!