Minneapolis—If migraines worsen in women on hormone replacement therapy, pharmacists should advise them to be evaluated by their physician for stroke risk.

That’s according to a presentation at the International Stroke Conference 2016 in Los Angeles, which reported that women who currently used HRT and reported more severe migraines were 30% percent more likely to have an ischemic stroke than those never on the therapy or those who used HRT in the past but also had worsening migraines.

Researchers from the Zeenat Qureshi Stroke Institute in Minneapolis and colleagues also found that women currently on hormone therapy were more likely to experience worsening migraines than women who never started or had been on HRT in the past.

“Many post-menopausal women use hormone replacement therapy, and a large number also experience migraines, although we’re not sure if these put them at greater risk of stroke.

The question we wanted to address was whether there is a greater risk of stroke if migraines are becoming more severe while taking hormone replacement,” said lead author Haseeb A. Rahman, MD, who also is a neurology resident at Houston Methodist Hospital in Texas. “While earlier studies have looked at both as risk factors for stroke, they have sometimes come to different conclusions, and there are still ‘gray areas’ in our understanding.”

The study is touted as the first to look at a change in migraine severity with HRT as a risk factor for ischemic stroke.

For the study, researchers analyzed data for 82,208 women aged 50 to 79 years from the Women’s Health Initiative Study, which was begun by the National Institutes of Health in the early 1990s. When they enrolled in the study, all of the women reported having migraine headaches to some degree, with about 45% of them also using HRT.

At a follow-up visit 3 years after study initiation, participants completed a questionnaire to determine if their migraines had improved or worsened. Over 12 years of follow-up, 2,063 women had an ischemic stroke.

Results indicate that, compared with never or past users of HRT, rate of increase in severity of migraines was significantly higher among those who were currently on HRT therapy—17.3% versus 18.7% versus 20.6%.

“Patients that are current users of HRT that have an increase in severity of one grade or more of migraines are shown to have an increased risk of ischemic strokes,” according to the presentation. “Future studies are required to further investigate these correlations.”

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