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Epilepsy is the 4th most common neurological problem – only migraine, stroke and Alzheimer’s disease occurs more frequently.  There are many different ways to explain how often a disease occurs. Here’s a few points to consider.

What do the terms incidence and prevalence mean?

  • The incidence of epilepsy looks at the number of new cases of epilepsy in a given year or period of time. It’s often given in a ratio such as ‘x’ out of 1,000 persons develop epilepsy each year.
  • The prevalence of epilepsy looks at the number of people with epilepsy at any given point in time.  This includes people with new onset epilepsy as well as those who have had epilepsy for a number of years. This is usually given in a total number, such as ‘x million’ people, but can also be given as a ratio.
  • The difference between these numbers is how they are used and what they represent. To show the number of people affected right now, usually the prevalence number is used.  
  • To show how often epilepsy occurs, the incidence number is used.  These numbers are different because not everyone has seizures or epilepsy for the same amount of time. Some have epilepsy that goes away, others may live with epilepsy all their life.  
  • The incidence number also tells how many people in a certain group have epilepsy. For example, these numbers can show how often epilepsy occurs at different ages, in different ethnic groups, or in different regions.

What is the incidence of epilepsy in the United States?

  • The average incidence of epilepsy each year in the U. S is estimated at 150,000 or 48 for every 100,000 people.
  • Another way of saying this- each year, 150,000 or 48 out of 100,000 people will develop epilepsy.
  • The incidence of epilepsy is higher in young children and older adults. This means that epilepsy starts more often in these age groups.
  • When the incidence of epilepsy is looked at over a lifetime, 1 in 26 people will develop epilepsy at sometime in their life.

What is the prevalence of epilepsy in the United States? 

There are many different estimates of the prevalence of epilepsy. These numbers vary depending on when the studies were done, who was included and a host of other factors.

  • The number of people with epilepsy, using prevalence numbers, ranges from 1.3 million to 2.8 million (or 5 to 8.4 for every 1,000 people).
  • The estimate currently thought to be most accurate is 2.2 million people or 7.1 for every 1,000 people.
  • However, higher numbers of people report that they have active epilepsy, 8.4 out of 1,000 people. These numbers are even higher when people are asked if they have ever had epilepsy (called lifetime prevalence). 16.5 per 1,000 people reported that they had epilepsy at some point in their life.

For more information:  Epilepsy across the Spectrum: Promoting health and understanding – an IOM Report on Epilepsy

Authored by: Patricia O. Shafer RN, MN | Joseph I. Sirven, MD on 10/2013
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 3/2014
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