Table 2 Levels of evidence for the treatment of migraine
From: Migraine treatment in developmental age: guidelines update
Level A: two or more clinically controlled, randomized studies carried out according to good clinical practice (GCP), versus placebo or versus active treatment of proven efficacy |
Level B: one clinically controlled, randomized study carried out according to GCP or more than one well-designed clinical case–control study or cohort study |
Level C: favorable judgment of two-third of the Ad Hoc Committee members, historical controls, non-randomized studies, case reports |