Methodology of clinical trials of sumatriptan in migraine and cluster headache.

The clinical development of sumatriptan has involved large international multicentre trials. To allow comparison of results obtained in a variety of clinical settings, great emphasis was placed on the use of consistent methodology across the programme. This applied to selection of patients, trial design, symptom evaluation and statistical analysis. Patients were selected for the major trials if they fulfilled the International Headache Society's diagnostic criteria for migraine or cluster headache. Relief of the headache was used as the main efficacy measure and this was assessed using standardized self-rating scales. All major controlled trials in migraine employed a parallel group design to avoid carryover effects and to ensure blinding was not compromised; however, because of the rarity of cluster headache, a crossover trial was performed in this indication. Appropriate statistical analyses were then performed on the data. The rationale for the methodology adopted is discussed. Strict adherence to these principles has allowed us to compare the results of sumatriptan treatment across a wide range of countries and treatment settings, and a selection of different administration routes.