A review of evidence-based medicine and meta-analytic reviews in migraine.

The following systematic reviews and meta-analyses are presented and the results discussed: the evidence-based American guidelines, five systematic reviews on naratriptan, rizatriptan, eletriptan, sumatriptan and propranolol; a meta-analysis of sumatriptan, a meta-analysis of acute migraine therapy, a meta-analysis of triptans available in Canada and a large meta-analysis of oral triptans. The systematic reviews of several randomized trials of one drug overcome random effects in estimating treatment effect of the reviewed drug. The results from the large meta-analysis of several drugs are compared with head-to-head comparative trials. Results are generally the same in the meta-analysis and in the comparative trials, with some exceptions. Head-to-head comparisons should remain the 'gold standard' and meta-analyses are a useful supplement in cases when comparative trials are relatively small and when no comparative trials exist.