# How many people have the disease based on the prevalence?

#### alanend

##### New Member
Hi,

I know that

Prevalence=(persons with a given health indicator during a specified time period/
population during the same time period) X 100

So, if I know that the prevalence of a disease is 0.1-0.28 per 1000 population, how many people actually have the disease? The total population is 316 million. It seems straightforward but I can't seem to make it work out.

Thanks.

#### hlsmith

##### Omega Contributor
Where are you getting these numbers from, is this a class question? I am assuming the 0.1-0.28 is the 95% confidence interval?

Regardless, 316,000,000/1,000 = 316,000

so take 0.1 and 0.28 * 316,00 = 31,600-88,480

#### alanend

##### New Member
Hi,

Sorry I should have been more clear. My son has a rare form of epilepsy. I found the prevalence in a paper about European prevalence and was told the prevalence in the US was roughly the same. I am trying to figure out roughly how many people in America have it because this is something I am asked when I say it is "rare."

Thanks so much for your help!

Danielle

#### hlsmith

##### Omega Contributor
Sorry to hear the circumstances around the question. I wold look into the respective support group or forum for the condition. With technology these days, there is greater connectivity and camaraderie amongst those with conditions and their families. You can also work toward creating a wikipedia page if one does not exist.

You could also look at it as 1-3 in 10,000, that does seem very rare.

#### alanend

##### New Member
Thank you! Those are great suggestions! I do daily basic data analysis in SPSS for a living but my statistics are very rusty. I appreciate your help!