Anticonvulsants v placebo for number of patients who responded with ⩾50% reduction in migraine frequency at mean 9.6 weeks*
| Number of trials (n) | Comparisons | Weighted event rates | RBI (95% CI) | NNT (CI) |
|---|---|---|---|---|
| *Abbreviations defined in glossary; weighted event rates, RBI, NNT, and CI calculated from data in article using a random effects model. | ||||
| 10 (1341) | Anticonvulsants as a class v placebo | 49% v 20% | 71% (63 to 80) | 4 (3 to 5) |
| 4 (579) | Divalproex sodium v placebo | 47% v 21% | 74% (57 to 91) | 4 (3 to 12) |
| 1 (68) | Sodium valproate v placebo | 29% v 18% | 68% (47 to 89) | 4 (2 to 10) |
| 3 (498) | Topiramate v placebo | 48% v 22% | 74% (66 to 82) | 4 (3 to 6) |