This study employed a population sampling procedure based on households to determine within the Sydney (Australia) area a minimum point prevalence ratio of epilepsy (defined as 3 or more seizures diagnosed by a doctor). This produced an estimate of 7.5 cases/1,000 population. 70% of the sample were maintained on anticonvulsant therapy, and approximately 30% were seizure-free and off medication. Only 15–20% had more than 2 seizures/year. The present study indicates that epilepsy is more common than the generally accepted prevalence ratio of 1/200 and that anticonvulsant medication effectively controls the majority of cases.

This study has adopted a tested questionnaire, used in a population prevalence study, and distributed it to a sample of people identified as having epilepsy to determine the false-negative response rate for this type of epidemiologic study.

The prevalence of epilepsy was estimated by defining an initial prevalence ratio based on a population study and modifying this figure on the basis of various factors which influenced it. The definition required 3 seizures diagnosed by a doctor and the influencing factors included false-negative responses (where the diagnosis was confirmed), false reporting (where the diagnosis had not been established) and falsely low seizure counts (where therapy had reduced the number of seizure below the mandatory 3). As a result of these calculations the figure of approximately 1 in 50 was offered as a reliable and reasonable estimate of the true prevalence ratio of epilepsy within a well-defined Australian population.