Risk of taking oral contraceptives in patients with a history of migraine with neurological signs.

Clinical question " What is the risk of taking oral contraceptives in patients with a history of migraine with transient neurological signs? " A woman with a history of migraine associated with hemiparaesthesia, and possibly dysphasia, attended her general practitioner suffering from irregular and frequent menstrual cycles. The doctor considered treatment with oral contraceptives to control her cycles and possibly relieve her migraine attacks. He asked about the risk of treatment with oral contraceptives , compared with no treatment, in a patient with transient neurological signs associated with migraine. The interventions of interest were oral contraceptives. Ideally, we sought evidence from prospective follow-up studies of women taking oral contraceptives (OCs), in which groups were compared according to relevant outcomes. Case–control studies are a good research design to investigate the association between common exposures and rare outcomes, as in the current question. Unfortunately, this design is also subject to a range of possible biases that can distort the findings — recall bias, observation bias and various biases involving subject and control selection. Search PubMed and the Cochrane Library were searched for relevant articles with English abstracts published since 1989. Search terms included " migraine " combined with terms for oral contraceptives (" contraceptive agents " ; " contraceptivetial " ; " progestational hormones, synthetic "), and " stroke " or " cerebrovascular disorders. " Summary of findings This evidence search demonstrated the difficulties involved in, firstly, assessing the incidence of adverse effects of treatments and, secondly, in conveying these data to patients. We found no prospective studies comparing stroke risk in women taking OCs who did and did not have a history of migraine. Similarly, we found no prospective studies comparing stroke risk in women taking OCs who experienced migraine with neurological signs and those taking OCs who experienced uncomplicated migraine. Nevertheless, other kinds of evidence suggested that women taking OCs who had a history of migraine have a markedly increased relative risk of ischaemic stroke, although the difference in absolute numbers of women affected may not be as marked. A case–control study of women aged 20–44 years 1 found that the relative risk of ischaemic stroke in women with migraine and taking OCs was 16.9 times (95% CI, 2.72– 106) that of women without migraine and not taking OCs. Women with migraine who used low dose OCs (< 50 µg oestrogen) had 6.59 times (95% CI, 0.79– 54.8) the risk …