Table 1 Study-quality score

1 Clear definition of the objective of the study

2 Study design adequate for the objective of the study

3 Clear definition of the primary endpoint

4 Clear definition of the secondary endpoints

5 Adequate blinding of the study (at least double-blind)

6 Adequate randomisation and adequate description of the randomisation

7 Adequate presentation of early terminations/withdrawals from the study

8 Placebo-control group

9 A priori sample size calculation

10 Patient population representative of self-medication (patients e.g. with mild to moderately severe migraine and/or tension-type headache; no in-patients)

11 Adequate statistical methods and analysis

12 Correct interpretation of the statistical results