[Basic principles of epidemiological studies of epilepsy].

Objective: Until recently there were few epidemiological studies of epilepsy. This was probably due to lack of knowledge of concepts of epidemiology and lack of common criteria for the design of investigations. Fortunately, in recent years many studies have been published in both developed and undeveloped countries, in different age groups and dealing with all aspects of epilepsy. We wish to describe the main concepts of neuroepidemiology and methods of epidemiological measurements as applied to epilepsy.

Development: We describe the criteria for planning an epidemiological study including concept of the problem, selection of the model and methods and finally treatment of the data and interpretation of the results. We analyze the sample being studied and its variables. We define the concepts of clinical trial, field trial, transverse studies, sampling, study of cohorts, case control, metanalysis, sensitivity and specificity of a test. We quote the definitions and basic criteria of the International League against Epilepsy when beginning an epidemiological study of epilepsy. Finally, we review the most recent epidemiological studies, with particular emphasis on those carried out in our setting.

Conclusions: Epidemiological studies are fundamental to the establishment of conclusions and advances in the investigation of epilepsy. The support of an epidemiologist is essential.