title: Efficacy of botulinum toxin type A for the prophylaxis of episodic migraine headaches: a meta-analysis of randomized, double-blind, placebo-controlled trials.
abstract: OBJECTIVE
  To assess the efficacy of botulinum toxin type A in lowering the frequency of migraine headaches in patients with episodic migraines.
  
  
  METHODS
  Meta-analysis of eight randomized, double-blind, placebo-controlled trials.
  
  
  METHODS
  A total of 1601 patients with a history of episodic migraine headaches classified as those experiencing headaches fewer than 15 times/month over a 3-month period.
  
  
  RESULTS
  PubMed, Google Scholar, and the Cochrane Library were searched from inception to October 2007 in order to locate randomized, double-blind, placebo-controlled trials that compared the efficacy of pericranial botulinum toxin A injections with placebo in the prevention of migraines in patients with a history of episodic migraine headaches. The primary outcome of interest was change from baseline to end point in migraine frequency (number of migraines/month). A random effects model was used to combine study results, and the standardized mean difference (Cohen's d) in migraine frequency between the placebo and botulinum toxin A groups was reported. Effect sizes (d) less than 0.2 were considered small. Quality assessment was performed by using the Downs and Black scale. Eight randomized, double-blind, placebo-controlled clinical trials (1601 patients) presented a quantitative assessment of the efficacy of botulinum toxin A versus placebo. The overall treatment effect size of botulinum toxin A over placebo for 30, 60, and 90 days after injection was d -0.06 (95% confidence interval [CI] - 0.14-0.03, z=1.33, p=0.18), d -0.05 (95% CI -0.14-0.03, z=1.22, p=0.22), and d -0.05 (95% CI -0.13-0.04, z=1.07, p=0.28), respectively. Even after controlling for a high placebo effect, and after dose stratification, no significant effect of botulinum toxin A in reducing migraine frequency/month was seen over placebo.
  
  
  CONCLUSIONS
  Botulinum toxin A for the prophylactic treatment of episodic migraine headaches was not significantly different from placebo, both from a clinical and statistical perspective.
authors: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Ontario, Canada.
authors: Adam J
authors: AJ
authors: Shuhendler
authors: Soyoung
authors: S
authors: Lee
authors: Michelle
authors: M
authors: Siu
authors: Stephanie
authors: S
authors: Ondovcik
authors: Kyla
authors: K
authors: Lam
authors: Awatif
authors: A
authors: Alabdullatif
authors: Xiaochu
authors: X
authors: Zhang
authors: Márcio
authors: M
authors: Machado
authors: Thomas R
authors: TR
authors: Einarson
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000517:prevention & control*; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A