What's the chance of being diagnosed with an acoustic neuroma?

[ANSydney]

We all know that the incidence of acoustic neuromas (vestibular schwannomas) is somewhere between 1~2/100,000 people/year. This is pretty well undisputed; which is very rare to have any information undisputed in the world of acoustic neuromas!

However, given this information, what is the chance of someone being diagnosed with an acoustic neuroma in their lifetime?

If we all lived for 1 year and we were told the incidence is 1~2/100,000 people/year, then incidence would be the same as chance. However, last time I looked we live more like 50~100 years.

So, given the incidence is 1~2/100,000 people/year and people live for 50~100 years/person, the chance of being diagnosed with an acoustic neuroma would be 1 in 1000.

We sound special when we're told there's a 1 in 100,000 chance of getting an acoustic neuroma. But, the incidence figure translates to 1 in 1000 chance. We don't sound so special now.

So, from the perspective of an individual, are we more like 1 in 100,000 chance or 1 in 1,000 chance of being diagnosed within our life time with an acoustic neuroma?

All opinions and comments welcome.

[rupert]

I guess it all depends on how you look at it as there are a lot of variables too figures like this.  Here's my opinion.  There are approx. 329 million people in the US.   Around 4 million people are born every year and about the same die every year.  It's just a continuous replacement so, if you figure the age when people are usually diagnosed is between 40 and 60 then every year there are just millions of new people entering that group.  I think that the 1 in 100,000 chance is over your entire life.  This would equate to approx. 3300 new people each year in the US that would be diagnosed with an AN.

[ANSydney]

There are approx. 329 million people in the US.  OK
Around 4 million people are born every year and about the same die every year. Sounds about right.
It's just a continuous replacement so, if you figure the age when people are usually diagnosed is between 40 and 60 then every year there are just millions of new people entering that group.  I don't think the year you are diagnosed in changes the equation. Whether you are diagnosed on the day you are born or the day you die, you still count as one incident. You do still however count towards the denominator for about 100 years.
This would equate to approx. 3300 new people each year in the US that would be diagnosed with an AN. Yes, that's the number.

[ANSydney]

Just to get a better understanding, I'm going to run a simulation. We're looking at a difference of a factor of 100, so we can use nice round numbers to see how incidence translates to chance of someone being afflicted.

The simulation will be a case of a closed system of 1000 people, with 10 born each year and 10 that die each year with a lifespan of 100 years. The incidence of an infliction will be set to 1/100 people/year and we'll see how this translates to the chance of the affliction. The simulation will be run so that people can only be afflicted from ages 40 to 60, so I'll run the simulation for 100 years and then look at the second 100 years. Will it be 1% or almost 100% chance of being afflicted in a lifetime. This will then translate into telling us the lifetime chance of getting an acoustic neuroma.

[Kathleen_Mc]

ANSydney
I'm sure the incidence of AN's being found in a living person and in that of someone post mortem are different since not ALL AN's ever show symptoms and go un-diagnosed (I'm sure I read a study about the incidence of undiagnosed AN's in the past but can't remember the difference in numbers) only to be found when an autopsy is performed......then there's got to be a percentage of those who do not have autopsy done who have an un-diagnosed AN. And of course with the development of MRI they are found more often so it would matter how old the study is that you are reading/getting your stat's from.
Challenge your brain !
Kathleen

[ANSydney]

Hi Kathleen,

For now I'm looking at just incidence of an AN (~1 diagnosis/100,000 people/year and chance of being diagnosed with an AN (~1 diagnosed/100,000 people or ~1 diagnosed/1,000 people). Just to use round numbers, we'll assume all lifetimes are 100 years, so chance of being diganosed with an AN can be written as ~1 diagnosed/100,000 people/100 years or ~1 diagnosed/1,000 people/100 years. Later we can add prevalence (that is diagnosed and undiagnosed AN).

I'm into challenging my brain. And saving it!

[ANSydney]

I've done the analysis and for the simpler analysis, it's 100% on average (some get afflicted more than once, some not at all, most once, with an average of one).

So, for an AN incidence of 1 diagnosis/100,000 people/year (it's a bit more than this for AN), for people living 100 years (it's a bit less for this and between the two, we're about right), we have:

* The chance of someone being diagnosed with an acoustic neuroma in their lifetime is 1/1,000. That is, 0.1%.
* The chance of an individual, that you meet at random, being diagnosed with an acoustic neuroma in the past year is 1/100,000. That is, 0.001%.
* The age distribution does not matter. Acoustic neuromas can occur at any age without affecting the incident rate. All that matters is that you have a 0.1% chance of diagnosis in your lifetime and that your lifetime is 100 years.

Please challenge this. Once it's finalized, I'll move onto prevalence, which is what is the chance of someone getting an acoustics neuroma in a lifetime, both diagnosed and undiagnosed. This will be taken from published postmortem studies.

[ANSydney]

About 1 in 100,000 per year, in the U.S. that amounts to about 3,000 cases a year.  So your risk of developing one in a lifetime is roughly 1 in 1,000.   Off the top of my head, most AN's are diagnosed after the age of 30 with most of them diagnosed around middle age, you would be on the early end of the spectrum.  It does happen but in your age range its rare within an already rare condition.

A lot of things can cause hearing loss and fullness so odds are you may not have a tumor.  Though since you are having symptoms I would get them checked out with a doctor ASAP, maybe an ENT.  They might prescribe you some steroids in an effort to regain your hearing (at least temporarily).  The only definitive way to test for a tumor is an MRI.

Edit: Stat correction..brain fog 

Smart person Trippy.

[PaulW]

I believe the incidence is actually around 2.1 per 100,000 per year. This is based on autopsy studies.
Around 1.4 per 100,000 are diagnosed each year..
one third of people with an Acoustic Neuroma will take them to their grave without knowing.

[ANSydney]

I believe the incidence is actually around 2.1 per 100,000 per year. This is based on autopsy studies.

I'd be interested in the source. My figures are much larger for prevalence during a lifetime.

[keithmac]

I believe the incidence is actually around 2.1 per 100,000 per year. This is based on autopsy studies.

I'd be interested in the source. My figures are much larger for prevalence during a lifetime.

How up-to-date are any such statistics anyway?  In our little country, around my tiny geograpical region, there seems to be a disproportionate number of sufferers....

[ANSydney]

With regards to autopsy studies, even a hundred years is still accurate. When it comes to diagnosis AN it has been rising since the advent and availability of MRI.

[ANSydney]

A paper has been published in the last couple of days. Although it's looking at better ways to treat these tumors, it did mention the lifetime incidence https://www.ncbi.nlm.nih.gov/pubmed/29088993

"with a lifetime incidence of approximately 1 in 1000"

Did I do well?

I think we can now place this piece of the puzzle down. Let the remainder of the puzzle be worked on (it's not as mysterious as it first looks!)

[ANSydney]

Just published today some information towards the prevalence. That is, how many people get an acoustic neuroma in a lifetime - either diagnosed (that's us) or undiagnosed. I've said a few times it's something like 1 in 100 people will develop a vestibular schwannoma in a lifetime. The paper published today is https://link.springer.com/content/pdf/10.1007%2Fs11060-017-2661-z.pdf . "The vast majority of these patients were participants in the Mayo Clinic Study of Aging (MCSA), which included at least one non-contrast MRI" so presumably an unbiased selection.

7 out of 2472 people had a vestibular schwannoma. That's 0.3% I hear you say. Well there's a couple of things that may explain the shortfall:
1) Most of the MRI's where done without contrast, so many, particularly small tumors, could have been missed
2) "Median age of the 45 patients with intracranial tumors was 74 (range 51-95)". So people still had more years to develop a vestibular schwannoma in their lifetime. Tumors appear more probable as you get older.

So in summary, for vestibular schwannomas
1) Incidence is 1~2 diagnosed / 100,000 people / year
2) Lifetime incidence of  ~1 diagnosed/1,000 people
3) Lifetime prevalence ~1/100 people, most of which never get diagnosed