| Study characteristics |
| Methods |
Randomised, placebo‐controlled, double‐blind trial. 2 parallel groups. Withdrawal study |
| Participants |
17 patients (age range not reported). Data from all 17 patients available and evaluated. Common and classical migraine (diagnostic criteria not specified) |
| Interventions |
2 capsules (25 mg each) of powdered feverfew leaves daily for 6 months |
| Outcomes |
Frequency of headache. Incidence of nausea and vomiting. Global assessment of efficacy. Adverse events |
| Notes |
All patients had taken raw feverfew leaves for the previous 3 to 4 years. Small sample size. Oxford score: 4/5 (R = 1, B = 2, WD = 1) |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Successive patients were allocated randomly to receive either feverfew or identical placebo capsules in numbered packs |
| Allocation concealment (selection bias) |
Unclear risk |
No details provided |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Study described as double‐blind and study medications described as identical but no further details provided on who was blinded |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Data from all participants evaluated |
| Selective reporting (reporting bias) |
Low risk |
Results reported for all pre‐specified outcome measures (some outcome measures such as duration or intensity were not pre‐specified) |
| Other bias |
High risk |
High risk of bias due to small sample size (n = 17) |
