| Study characteristics |
| Methods |
Randomised, placebo‐controlled, double‐blind trial. Cross‐over. Treatment study |
| Participants |
72 patients aged 24 to 72 years. Data from 59 patients evaluated. Common and classical migraine (as defined by Blau 1984) |
| Interventions |
1 capsule (mean weight 82 mg) of dried powdered feverfew or placebo daily for 4 months |
| Outcomes |
Frequency and intensity of headache. Incidence of nausea and vomiting. Global assessment of efficacy. Adverse events |
| Notes |
Heterogeneous patient sample. 1‐month placebo run‐in. No wash‐out period. Subgroup analysis in classical/common migraine patients. Oxford score: 4/5 (R = 2, B = 1, WD = 1) |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Described as random allocation but no further details provided |
| Allocation concealment (selection bias) |
Unclear risk |
Not described |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Probably done. Described as double‐blind. Placebo capsules described as similarly prepared and not possessing "any anti‐secretory activity". Not specified who was blinded |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Clear description of drop‐outs and reasons |
| Selective reporting (reporting bias) |
Low risk |
Relevant outcome measures included results reported for pre‐defined outcome measures |
| Other bias |
Unclear risk |
Unclear risk of bias due to sample size (n = 72) |
