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EDITORIALS: Richard B Lipton and Carol A Derby Migraine with aura BMJ 2008; 337: a745 [Full text]

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Primary Care of Migraine with Aura.

GEORGE Y. CALDWELL, SINGAPORE 259858   (22 August 2008)

Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk?

Mark Woodward   (26 August 2008)

Re: Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk?

Anne E Scott, Stephen J Leslie   (7 September 2008)

Primary Care of Migraine with Aura. 22 August 2008
GEORGE Y. CALDWELL, GENERAL PRACTITIONER 31 BALMORAL PARK, #18-33, SINGAPORE 259858 Send response to journal: Re: Primary Care of Migraine with Aura.	Consultants in the big hospitals must see terrible cases of Migraine. Such as those that have not resolved in General Practice. In Primary Care, initially a 50 mg. IM injection of Chlorpromazine has been found most effective even in the very severe recurrent attacks of Migraine giving instant comfort and relief to the patient. The Blood Pressure should be checked beforehand in case it is already low. Chlorpromazine will lower it further. Competing interests: None declared
Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk? 26 August 2008
Mark Woodward, Professor of Medicine Mount Sinai Medical School, New York 10029, USA Send response to journal: Re: Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk?	Kurth et al (1) provided the most reliable information, to date, for an association between migraine with aura and myocardial infarction (MI) amongst women, and added to previous knowledge of a similar association for ischaemic stroke. The same research group’s recent BMJ paper (2) claims to add to this by showing that migraine with aura is associated with increased risk of ischaemic stroke only among women with low vascular risk scores, and is associated with increased risk of MI only among women with high vascular risk scores. This derives from p values found in their stratified analyses of risk according to Framingham coronary risk scores. However, no mention is made of tests for interaction across these strata, which would seem to be the bare essential for deciding whether subgroup differences were not due merely to random noise (3). Using the numbers provided in the paper (which only allow unadjusted analyses) there is no evidence of interaction (p>0.10) for any of the outcomes used in the paper, across the authors’ four risk strata, or comparing just the low and high groups. I am also uneasy with Kurth et al’s comparisons of relative risks across strata of different ‘background’ risk without quantification, and interpretation, of the constituent absolute risks (and their confidence limits), appropriately standardised. A risk difference of, say, one in a hundred will, a priori, have a much greater relative effect in the low (<1% 10-year) Framingham risk group compared to the high (>10%). References 1. Kurth T, Gaziano JM, Cook NR, Logroscino G, Diener HC, Buring JE. Migraine and risk of cardiovascular disease in women. JAMA 2006; 296: 283- 91. 2. Kurth T, Schürks M, Logroscino G, Gaziano JM, Buring JE. Migraine, vascular risk, and cardiovascular events in women: prospective cohort study. BMJ 2008; 337: a636 doi:10.1136/bmj.1636. 3. Matthews JN, Altman DG. Statistics notes. Interaction 2: Compare effect sizes not P values. BMJ 1996; 313: 808. Competing interests: None declared
Re: Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk? 7 September 2008
Anne E Scott, Cardiology SpR Raigmore Hospital IV2 3UJ, Stephen J Leslie Send response to journal: Re: Re: Migraine with aura and cardiovascular disease: does the relative risk vary with the absolute risk?	We were interested to read the recent paper by Kurth et al reporting the association, in women, between migraine with aura and risk of a vascular events particularly in those deemed relatively low risk using conventional (Framingham) risk stratification.(1) We are surprised that the authors made no reference to the well documented association between migraine and a patent foramen ovale (PFO) in this context. A persisting embryonic defect in the intra-atrial septum, PFO is present in up to 27% of the general population. (2,3) In patients suffering migraine with aura a significantly higher prevalence has been reported (46%). (4) In addition, patients under the age of 55 with cryptogenic stroke (i.e. those lacking other vascular risk factors) have also been shown to have an increased prevalence of PFO (47%). (5) Whilst concrete evidence of causality is lacking it would seem reasonable to hypothesise that intermittent right to left shunting vasoactive amines not metabolically degraded in the lungs and paradoxical emboli could account for the increased vascular risk seen in these patients. We believe that Kurth et al should consider this issue and include the presence of a PFO in their future assessment of cardiovascular risk in this population. (1) Kurth et al. Migraine, vascular risk, and cardiovascular events in women: prospective cohort study. BMJ 2008;337:a636 (2) Meissner et al. Patent foramen ovale: innocent or guilty? Evidence from a prospective population-based study. J Am Coll Cardiol. 2006 Jan 17;47(2):440-5 (3) Sacco et al. Guidelines for Prevention of Stroke in Patients With Ischemic Stroke or Transient Ischemic Attack. Stroke. 2006;37:577- 617. (4) Lamy et al. Clinical and imaging findings in cryptogenic stroke patients with and without patent foramen ovale: the PFO-ASA Study: Atrial Septal Aneurysm. Stroke. 2002; 33: 706–711 (5) Schwerzmann et al.Prevalence and size of directly detected patent foramen ovale in migraine with aura. Neurology. 2005 Nov 8;65(9):1415-8 Anne Scott. Specialist Registrar in Cardiology Stephen J Leslie. Consultant cardiologist and Honorary Reader Highland Heartbeat Centre Cardiac Unit Raigmore Hospital Inverness IV2 3UJ Competing interests: None declared