Incidence and Prevalence
Epilepsy and Seizure Statistics
- Epilepsy and seizures affect nearly 3 million Americans of all ages, at an estimated annual cost of $17.6 billion in direct and indirect costs.
- Approximately 200,000 new cases of seizures and epilepsy occur each year.
- Ten percent of the American population will experience a seizure in their lifetime.
Health condition statistics are typically expressed in terms of incidence and prevalence in a particular population within a specific period of time. Incidence is a measure of the number of new cases of a medical condition that occur in the population during a measured amount of time, usually one year. Prevalence is defined as the total number of existing cases of a disease in a specific population at a stated point in time. In any one day, at a certain time, there are a specific number of people with a certain disorder.
There is no central registry of cases of epilepsy or seizures in the United States. Epidemiologists base their estimates on peer-reviewed studies of medical records at specific institutions or in defined local communities. Surveys of physicians and patients, self reporting, and studies in matched populations or segments of populations overseas may also be taken into account.
From this mixture of sources, leading experts in the field have arrived at the following estimates of the incidence and prevalence of seizures and epilepsy in the United States:
Incidence -- Seizures:
- 300,000 people have a first convulsion each year.
- 120,000 of them are under the age of 18.
- Between 75,000 and 100,000 of them are children under the age of 5 who have experienced a febrile (fever-caused) seizure.
Incidence -- Epilepsy:
- 200,000 new cases of epilepsy are diagnosed each year.
- Incidence is highest under the age of 2 and over 65.
- 45,000 children under the age of 15 develop epilepsy each year.
- Males are slightly more likely to develop epilepsy than females.
- Incidence is greater in African American and socially disadvantaged populations.
- Trends show decreased incidence in children; increased incidence in the elderly.
- In 70 percent of new cases, no cause is apparent.
- 50 percent of people with new cases of epilepsy will have generalized onset seizures.
- Generalized seizures are more common in children under the age of 10; afterwards more than half of all new cases of epilepsy will have partial seizures.
Prevalence -- Epilepsy:
- Prevalence of active epilepsy (history of the disorder plus a seizure or use of antiepileptic medicine within the past 5 years) is estimated as nearly 3 million in the United States.
- Prevalence tends to increase with age.
- 326,000 children through age 15 have epilepsy.
- More than 300,000 persons over the age of 65 have epilepsy.
- Higher among racial minorities than among Caucasians.
- Cumulative incidence (risk of developing epilepsy):
- By 20 years of age, one percent of the population can be expected to have developed epilepsy.
- By 75 years of age, three percent of the population can be expected to have been diagnosed with epilepsy, and ten percent will have experienced some type of seizure.
Epilepsy risk in special populations:
The basic, underlying risk of developing epilepsy is about one percent. Individuals in certain populations are at higher risk. For example, it is estimated that epilepsy can be expected to develop in:
- 25.8 percent of children with mental retardation
- 13 percent of children with cerebral palsy
- 50 percent of children with both disabilities
- 10 percent of Alzheimer patients
- 22 percent of stroke patients
- 8.7 percent of children of mothers with epilepsy
- 2.4 percent of children of fathers with epilepsy
- 33 percent of people who have had a single, unprovoked seizure
- 70 percent of people with epilepsy can be expected to enter remission, defined as 5 or more years seizure free on medication.
- 35 percent of people with mental retardation, cerebral palsy, or other neurological condition will enter remission.
- 75 percent of people who are seizure free on medication for 2 to 5 years can be successfully withdrawn from medication.
- 10 percent of new patients fail to gain control of seizures despite optimal medical management.