Hering 1992.
| Methods | Prospective, randomised, double‐blind, single cross‐over trial. 2‐week washout period for previous migraine prophylactic medication. No baseline period. Total duration: 16 weeks Discontinuation rate: dropout 3.1% for active treatment; 6.3% for placebo Compliance (adherence) data: compliance assessed by pill count and blood valproate levels, but pill count data not reported Rule for use of acute medication: patients' normal analgesics permitted Methodological quality score: 4 |
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| Participants | Inclusion: Ad Hoc Committee criteria; migraine onset more than 2 years prior to screening; at least 4 attacks per month for 2 years. No information about mixed or combination headaches Exclusion: secondary headaches were adequately excluded. It is not reported whether daily headaches were excluded. Analgesic overuse headaches were not adequately excluded. Other exclusions: contraindications to valproate, renal or hepatic abnormality, psychiatric disorder, pregnancy or reproductive intentions, change in use of oral contraception, alcohol or drug abuse, participation in another headache study, other chronic medication use Setting: single headache clinic Country: Israel 32 migraine patients participated. Demographic data available on the 29 who completed the trial. 4 had migraine with aura, and 25 migraine without aura. 23 females and 6 males; age range 18 to 54 years |
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| Interventions | Sodium valproate versus placebo (8 weeks). Dosage: 800 mg/day | |
| Outcomes | Number of migraine attacks per 8 weeks. Sum of individual attack severity (1 to 3) per 8 weeks. Sum of individual attack duration (hours) per 8 weeks Time point(s) considered in the review: entire 8‐week treatment phase |
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| Notes | Funders of the trial: not reported | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Description of method for random sequence generation is lacking |
| Allocation concealment (selection bias) | Unclear risk | No information |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Both clinicians and participants were blinded. Placebo had same appearance as verum |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | No information |
| Incomplete outcome data (attrition bias) All outcomes | High risk | AEs reported but number of safety evaluable participants on each drug unclear |
| Selective reporting (reporting bias) | Low risk | No suspicion of selective reporting of outcomes, time points, or analyses |