Lots of alternative therapies are advocated for migraine. Few of them are supported by good evidence. An exception could be the herbal remedy FEVERFEW.
This review is an update of a previously published review in the Cochrane Database of Systematic Reviews on ‘Feverfew for preventing migraine’. Feverfew (Tanacetum parthenium L.) extract is a herbal remedy, which has been used for preventing attacks of migraine. Our aim was to systematically review the evidence from double-blind, randomised, clinical trials (RCTs) assessing the clinical efficacy and safety of feverfew monopreparations versus placebo for preventing migraine.
For this updated version of the review we searched CENTRAL, MEDLINE, EMBASE and AMED to January 2015. We contacted manufacturers of feverfew and checked the bibliographies of identified articles for further trials.
We included randomised, placebo-controlled, double-blind trials assessing the efficacy of feverfew monopreparations for preventing migraine in migraine sufferers of any age. We included trials using clinical outcome measures, while we excluded trials focusing exclusively on physiological parameters. There were no restrictions regarding the language of publication.
We systematically extracted data on patients, interventions, methods, outcome measures, results and adverse events. We assessed risk of bias using the Cochrane ‘Risk of bias’ tool and evaluated methodological quality using the Oxford Quality Scale developed by Jadad and colleagues. Two review authors independently selected studies, assessed methodological quality and extracted data. We resolved disagreements concerning evaluation of individual trials through discussion.
We identified one new study for this update, resulting in a total of 6 trials (561 patients) meeting the inclusion criteria. Five of the 6 trials reported on the main outcome measure which was migraine frequency. Although 5 of the trials were generally of good methodological quality, all studies were either of unclear or high risk of bias with regards to sample size. Pooled analysis of the results was not possible due to the lack of common outcome measures and heterogeneity between studies in terms of participants, interventions and designs. The most recent trial added to this update was rigorous and larger (n = 218) than previous studies. It used a stable feverfew extract at a dose determined by a previous dose-finding trial. It reported that feverfew reduced migraine frequency by 1.9 attacks from 4.8 to 2.9 and placebo by 1.3 from to 4.8 to 3.5 per month. This difference in effect between feverfew and placebo was thus 0.6 attacks per month. For the secondary outcome measures such as intensity and duration of migraine attacks, incidence and severity of nausea and vomiting, and global assessment no statistically significant differences between feverfew and placebo were reported.
The results of previous trials were not convincing: three trials reporting positive effects of feverfew were all of small sample size (17 to 60 participants), while two rigorous trials (n = 50, 147) did not find significant differences between feverfew and placebo.
Only mild and transient adverse events of feverfew, most commonly gastrointestinal complaints and mouth ulcers, were reported in the included trials.
We concluded that, since the last version of this review, one larger rigorous study has been included, reporting a difference in effect between feverfew and placebo of 0.6 attacks per month. This adds some positive evidence to the mixed and inconclusive findings of the previous review. However, this constitutes low quality evidence, which needs to be confirmed in larger rigorous trials with stable feverfew extracts and clearly defined migraine populations before firm conclusions can be drawn. It appears from the data reviewed that feverfew is not associated with any major safety concerns.
So, good or bad news for migraine sufferers? I suppose it depends on whether you are an optimist or a pessimist. I would say that, considering the mostly bad news about alternative medicine for migraine, it is relative good news: patients who want to try something ‘natural’ could do so, particularly in view of the lack of serious risks.