The prevalence of epilepsy is generally taken as between 5 and 10 cases per 1000 persons, and the overall incidence as about 50 cases per 100,000 persons. The rates are dependent on case ascertainment and on definitions used. The prognosis depends on many factors, including the number of seizures at presentation, the seizure type and the use of anti-epileptic drugs. Epilepsy carries an excess mortality; the cause of death can be unrelated to epilepsy, related to the underlying disease causing epilepsy, or related to epilepsy itself.