We frequently say that 1️⃣ in 2️⃣6️⃣ people in the US will develop #epilepsy in their lifetime. This is a staggering statistic that highlights the importance of #EpilepsyAwareness, research, and better treatments...
But how did we arrive at this number? 🤔 #MedTwitter #tweetorial
But how did we arrive at this number? 🤔 #MedTwitter #tweetorial
2)Incidence is the number of new cases over some period of time - incidence of epilepsy being highest in the very young and very old.
Prevalence is the number of active cases within the total population at risk - the statistic of 1 in 100 people have active epilepsy at any time.
Prevalence is the number of active cases within the total population at risk - the statistic of 1 in 100 people have active epilepsy at any time.
3) within those 100 people may be some that had epilepsy in the past that has remitted or some that have not developed epilepsy yet, but will. Only 1 has active epilepsy and is counted. So what is the likelihood of being personally impacted by epilepsy in a lifetime?
4) To understand the 1️⃣ in 2️⃣6️⃣ statistic, read Hesdorffer DC, et al. Neurology 2011;76:23-27.
ncbi.nlm.nih.gov/pubmed/21205691 ncbi.nlm.nih.gov/pubmed/21205691
ncbi.nlm.nih.gov/pubmed/21205691 ncbi.nlm.nih.gov/pubmed/21205691
5) They utilized data from the Rochester Epidemiologic Project which captures all medical records in southern MN. To identify cases of epilepsy, they reviewed data between 1960-1979.
6) From this data, they calculated two values:
Cumulative incidence(CI): summation of age-specific incidences, number of new cases of epilepsy divided by number at risk
Lifetime risk(LR): probability someone will develop epilepsy over a lifetime
Cumulative incidence(CI): summation of age-specific incidences, number of new cases of epilepsy divided by number at risk
Lifetime risk(LR): probability someone will develop epilepsy over a lifetime
7) The key difference in these calculations is the impact of death - not from epilepsy, but from other cause before epilepsy could develop.
Cumulative incidence assumes those who die have the same risk for developing epilepsy as those that survive. It may thus overestimate
Cumulative incidence assumes those who die have the same risk for developing epilepsy as those that survive. It may thus overestimate
8) Lifetime risk calculates zero risk of developing epilepsy after death. This is important because incidence of epilepsy is highest in people over 65, but risk of death for other causes is also highest in this age group.
9) 412 people developed epilepsy over the period studied, with incidence increasing from 1960-69 compared to 1970-79.
Read the paper to dive deep into the calculations, but they arrived at a lifetime risk of epilepsy of 3.9% by age 97y
Read the paper to dive deep into the calculations, but they arrived at a lifetime risk of epilepsy of 3.9% by age 97y
10) Taking a US population of 301,139,947 in 2007, 11,744,457 (3.9%) would develop epilepsy in their lifetime. Dividing the number with epilepsy by the total population get us to the 1️⃣ in2️⃣6️⃣ statistic
11)This number underscores the importance of recognizing #epilepsy as a major public health concern.
Shortcomings of this calculation include using data from over 40 y before this study- certainly diagnosis of epilepsy improved over that time.
Shortcomings of this calculation include using data from over 40 y before this study- certainly diagnosis of epilepsy improved over that time.
12)The population used may not be generalizable to all of the US - as locations with high volumes of at risk populations (ie elderly, veterans, etc) may have different lifetime risk. Regardless, we didn’t have nationwide data of adequate quality for this purpose.
13) this number is also calculated specifically to the US and may not be the same for another country or region of the world where risk of epilepsy is even higher.
