Research to improve headache classification: Results, methods, and future challenges.

IntroductionThe international headache classification has been enormously important promoting research and clinical management of patients with headache. It is a living document that develops from edition to edition and changes have been increasingly based on research, so called classification research. The aim of the present review is to present recent results of such research and to characterize the methods available for it.MethodsPublished research was identified by systematic search of PubMed. Lists of references of identified articles and the table of content of the last five years of Cephalalgia were screened.ResultsThe major results of identified articles are summarized. Thereafter the different methodologies applied in these studies are described. Finally, some suggestions are made for the future consideration of the fourth classification committee.ConclusionClassification research is emerging as an important avenue of headache research. It has a multitude of different designs available and many of them do not need advanced equipment.