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Meta-Analysis Suggests PFO-Migraine Link

BY ALICIA AULT
Elsevier Global Medical News

CHICAGO (EGMN) - There appears to be an association between patent foramen ovale and migraine with aura, according to a meta-analysis of published literature presented June 8 at the annual meeting of the American Headache Society.

Dr. Todd J. Schwedt of Washington University in St. Louis and Dr. Bart M. Demaerschalk and Dr. David W. Dodick of the Mayo Clinic, Scottsdale, conducted the meta-analysis.

About 25% of the U.S. population has a patent foramen ovale (PFO), a congenital defect in the septum between the left and right atrium, according to Dr. Schwedt, who presented the analysis.

It has been suggested that PFO and migraine are associated and several device makers are testing PFO closure devices to reduce the frequency and severity of headache.

Dr. Schwedt and his colleagues did a systematic MedLine review of the time period 1966-2006, using the search terms of heart septal defects, atrial; PFO; migraine disorders, and migraine. They included studies that reported only on PFOs, not PFOs in combination with other defects. PFOs had to be diagnosed by catheterization or echocardiography studies. The trials were only included if they had quantitative data on outcomes.

The researchers assigned a grade to each study. A high-grade study, for instance, meant that further research was very unlikely to change confidence in the results. A moderate grade was assigned if further research was likely to have an important impact on confidence, and a low grade if further research was very likely to have an important impact.

They used a fixed-effects meta-analytical technique to calculate summary odds ratios with 95% confidence intervals. Initially, the researchers identified 83 articles, but those that met inclusion criteria were nine articles on prevalence of PFO in migraine, four on prevalence of migraine in PFO, and five on the effect of PFO closure in migraine.

Prevalence of PFO in migraine patients was 22%-61% in the nine studies, higher than expected in the general population. In migraines with aura, the prevalence was13%-50%; without aura it was 3%-25%.

But, the grade of evidence was low in each study, Dr. Schwedt said.

Th prevalence of migraine with aura in patients with PFO was 41%-52%. Without aura, the prevalence was 16.2%. The grade of evidence was moderate.

In three of those four studies, the authors could calculate an odds ratio; the summary odds of having a PFO in migraine was 4.5, among a pooled study sample of 351 patients.

All the odds ratios were pooled to look at migraine and PFO in both directions. Overall, the summary odds ratio of the association between migraine and PFO was 5.06 (95% confidence intervals of 3.62-5.29), Dr. Schwedt said.

Looking at the effect of PFO closure on migraine, 10%-80% of patients had resolution, 13%-73% had improvement, and 0%-30% had no change in the 5 studies. The follow-up ranged from 6 to 12 months. But the grade of evidence was very low to low, Dr. Schwedt said.

Overall, there appears to be an association of migraine with aura and PFO, he said. But, for PFO closure, given the overall grade of evidence, "any estimate of effect is uncertain," he said.

Dr. Schwedt disclosed that he consults for AGA Medical, Medtronic, and other companies developing PFO closure devices, but the study was conducted independently, he said.

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