Efficacy of Botulinum Toxin Type A for the Prophylaxis of Episodic Migraine Headaches: A Meta‐analysis of Randomized, Double‐Blind, Placebo‐Controlled Trials
Bibliographic record
Abstract
STUDY OBJECTIVE: To assess the efficacy of botulinum toxin type A in lowering the frequency of migraine headaches in patients with episodic migraines. DESIGN: Meta-analysis of eight randomized, double-blind, placebo-controlled trials. PATIENTS: 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. MEASUREMENTS AND MAIN 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. CONCLUSION: Botulinum toxin A for the prophylactic treatment of episodic migraine headaches was not significantly different from placebo, both from a clinical and statistical perspective.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.022 | 0.037 |
| Meta-epidemiology (narrow) | 0.005 | 0.002 |
| Meta-epidemiology (broad) | 0.028 | 0.042 |
| Bibliometrics | 0.006 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.004 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".