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PAPERS: C L Chang, Michael Donaghy, and Neil Poulter Migraine and stroke in young women: case-control study BMJ 1999; 318: 13-18 [Abstract] [Full text]

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R C Peatfield   (20 January 1999)

Absolute risks need to be considered

Joanna Cais   (21 January 1999)

Migraine and stroke in older women

M J Campbell   (17 February 1999)

Migraine and ischaemic stroke

E Anne MacGregor   (2 March 1999)

Untitled 20 January 1999
R C Peatfield Send response to journal: Re: this article	Dear Sir The large scale study of the relationship between migraine and stroke published by Chang et al1 reinforces the conclusion of Tzourio2 and Merikangas3 that migraine carries a significant risk, even if attacks are not accompanied by an aura. I must confess to some surprise, however, that 68.9% of their migraine stroke cases and 71.9% of their migraine control subjects had attacks with aura and I think an explanation for this is required - most epidemiological studies (eg that of Russell4) suggest that only about 32% of migraine patients have auras, and a ratio only reaches 50% in specialist clinics5. It is common practice to only insist on withdrawing the combined contraceptive pill in patients with migraine with aura, and it will be helpful if the authors could provide information to support the working hypothesis that the increase in the odds ratio produced by oral contraceptives is minimal in patients without an aura and substantial in those with an aura, even if they do not smoke. Yours faithfully R C PEATFIELD MD FRCP CONSULTANT NEUROLOGIST References: 1 Chang CL, Donaghy M, Poulter N. Migraine and stroke in young women: case-control study. BMJ 1999; 318, 13-18. 2 Tzourio C, Tehindrazanarivelo A, Iglésias, Alpérovitch A, Chedru F, d'Anglejan-Chatillon J, Bousser M-G. Case-control study of migraine and risk of ischaemic stroke in young women. BMJ 1995; 310, 830-833. 3 Merikangas KR, Fenton BT, Cheng SH, Stolar MJ, Risch N. Association between migraine and stroke in a large-scale epidemiological study of the United States. Archives of Neurology 1997; 54, 362-368. 4 Russell MB, Rasmussen BK, Fenger K, Olesen J. Migraine without aura and migraine with aura are distinct clinical entities: a study of four hundred and eighty-four male and female migraineurs from the general population. Cephalalgia 1996; 16 239-45. 5 Peatfield R. Headache. Springer-Verlag, Berlin, 1986.
Absolute risks need to be considered 21 January 1999
Joanna Cais, Medical Student Epidemiology and Public Health Send response to journal: Re: Absolute risks need to be considered	Sir- CL Chang and colleagues quote the incidence rate from the WHO Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception as 5.5 per 100 000 woman years. It is then subsequently stated that the multiplicative effects of the other risk factors e.g. smoking are ‘worrisome’. The degree of concern that should arise is unclear, as the relative incidence of other conditions is not considered, and the absolute incidence of stroke in migrainous women with several risk factors is not referred to: surely this would have significant implications with regards to subsequent action in both Public Health and research areas. Subgroup analysis, although valuable in the context of the study, was undertaken with numbers too small to generate reliable statistics, hence the wide confidence intervals shown. We also feel it would have been beneficial in this study to investigate the relationship between the clinical features of the migraine and the stroke: this information could have been easily obtained and could further expand our understanding of the nature of the relationship. Cais,J., Ludlam,R., Moore,K., Taylor,H., Warwick,M.
Migraine and stroke in older women 17 February 1999
M J Campbell, Professor of Medical Statistics University of Sheffield Send response to journal: Re: Migraine and stroke in older women	Dear Editor The recent results by Chang et al1 relating migraine to the risk of stroke in younger women contrast with those of Walters et al2, who studied older women. In a cohort of women aged 45-64 they showed that migraine or headache in the past year was protective of death or stroke in a 12 year follow up. They were not able to distiguish different types of stroke. Whilst these results appear counter-intuitive they do reflect the fact that the period prevalence of migraine declines with age, whereas the risk of stroke increases. The differences may have a number of explanations: i)factors which carry a high risk in young people may be protective in older people (eg obesity, cholesterol level); ii) risk factors may change over time - the cohort from Walters et al was surveyed in 1967 and taking into account their age few if any of the women will have been on oral contraceptives; iii) differences in cohort studies and case control studies. Yours sincerely Michael campbell 1.Chang CL, Donaghy M, Poulter N. Migraine and stroke in young women: case-control study. BMJ 1999; 318, 13-18. 2. Walters WE, Campbell MJ, Elwood PC. Migraine, headache and survival in women. BMJ, 1983; 287: 1442-1443.
Migraine and ischaemic stroke 2 March 1999
E Anne MacGregor Send response to journal: Re: Migraine and ischaemic stroke	EDITOR - Chang et al report that the odds ratios for ischaemic stroke in young women with classical migraine (with aura) and simple migraine (without aura) were similar (1). These findings are at odds with earlier studies, which reported increased risk primarily in migraine with aura (2). We note the confidence interval for ischaemic stroke in migraine without aura included unity (OR2.97,0.66-13.5), unlike migraine with aura (OR3.81,1.26-11.5). Therefore, even by these data, a lesser risk in the former condition is not excluded. Another possible reason for the apparent discrepancy is that the authors may have failed to identify true aura. They characterised aura by at least one of the following symptoms just before or during the headache: visual disturbances, or abnormalities of speech, skin sensation or muscle power. Although their questionnaire was based on diagnostic criteria proposed by the International Headache Society, unfortunately their questions were too non-specific. Crucial characteristics of auras are symptoms, their duration and timing in relation to headache. The great majority are visual (95%), typically starting as a flickering, uncoloured zigzag line in the centre of the visual field gradually progressing laterally to the periphery of one hemifield, usually leaving a scotoma (3). Sensory or motor symptoms, if they occur, are usually also unilateral and rarely without associated visual symptoms (3). Auras typically last under one hour, resolving before headache onset, unlike the more general prodromal symptoms, which can precede the headache for several hours. Aura can be identified by asking "Have you ever had visual disturbances lasting 5-60 minutes followed by headache?" (4). Why is it important to distinguish between the different types of migraine? Based on previous evidence, the Faculty of Family Planning and Reproductive Health Care currently recommends that migraine with focal aura absolutely contraindicates combined oral contraceptives (5). Based on Chang et al, should the contraindication extend all women with migraine, at least if they smoke or are hypertensive? Migraine is common, hence numerous women could be deprived of a useful contraceptive. Further studies are necessary before accepting no difference in risk between the two main varieties of migraine. We can reassure the majority of young women with migraine of any type that the absolute risk of ischaemic stroke is minimal. However, it should still be possible to identify and counsel the minority at specific risk in order that they may choose an appropriate contraceptive and avoid other risk factors. E Anne MacGregor MBBS DFFP The City of London Migraine Clinic 22 Charterhouse Square London EC1M 6DX John Guillebaud MA FRCSE FRCOG MFFP Professor of Family Planning and Reproductive Health Department of Gynaecology, University College London Medical Director, Margaret Pyke Centre 73 Charlotte Street, London W1P 1LB 1 Chang CL, Donaghy M, Poulter N and World Health Organization Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception. Migraine and Stroke in Young Women. BMJ 1999;318:13-8. 2 Tzourio C, Tehindrazanarivelo A, Iglésias S, et al. Case-control study of migraine and risk of ischaemic stroke in young women. BMJ 1995;310:830-3. 3 Russell MJ, Olesen J. A nosographic analysis of the migraine aura in a general population. Brain 1996;119:355-361. 4 Gervil M, Ulrich V, Olesen J, Russell MB. Screening for migraine in the general population: validation of a simple questionnaire. Cephalalgia 1998;18:342-8. 5 MacGregor EA, Guillebaud J in conjuction with the Clinical and Scientific Committee of the Faculty of Family Planning and Reproductive Healthcare and the Family Planning Association. Recommendations for Clinical Practice. Combined oral contraceptives and ischaemic stroke. Br J Fam Planning 1998;24:53-60.