Abstract

The clinical research is the only way to give evidences of evidence based medicine which has a major role in the establishing management strategy. Clinical research consists of observational study and clinical trials. Observational studies include cohort study, case-control study, cross sectional study, case series study and others, and they have given numerous valuable informations, such as prevalence, natural history, clinical characteristics, and outcomes of migraine and other headache disorders. In desinging of clinical trials, we should consider not only scientific aspects but also ethical aspects because clinical trials always require dedication of participants. To be scientifically valid and valuable, clinical trials must have social and sicentific needs, methodological validity, and statistical reilability. Considering the requirements, needs and resources, investigators can make a design of clinical trials inclu- ding sample size, blinding methods, how to measure primary and secondary outcomes, statistical methods and others. Well-designed clinical trials only supply credible and useful evidence for evidence based medicine. Korean Journal of Headache 6(1):1-5, 2005