Link to study finding poor correlation between EDS and OSA

[Guest]

http://www.int.iol.co.za/index.php?clic ... 43&set_id=

This could explain why many people feel no better with CPAP, myself included, especially those with mild apnea.

I still can't get my username to work. This is george45

[Mikesus]

And another specific to arousals and EDS

CLINICAL IMPLICATIONS: The absence of a clear relationship between daytime sleepiness, sleep fragmentation and respiratory arousals suggest that the underlying mechanisms for daytime sleepiness in patients with obstructive sleep apnea is likely to be complex and multifactorial and needs further study.

Link to Study

[BP]

But...many, many people start cpap therapy and their daytime sleepiness goes away, myself included. May ahi was 60+ untreated, and I felt like an old man, constanly sleepy, now I feel great. Everyone is different, but there are plenty of good studies that point to osa as the cause, and cpap as the solution (at least until something less primitive comes along).

-BP

[DCTom]

This study does not really say that apnea does not cause EDS. It just says that for most people, it's either depression or diabetes. Which of course is true because these conditions are more prevalent than OSA. And remember, every study you read in the paper was sponsored by a corporation trying to sell something or make money. In this case, could be they are trying to sell anti-depression drugs. I'm not saying anti-depressents are bad, just that you have to figure this into the equation every time you read a story like this. And it seemes abundantly obvious that if you wake up all night long, you're going to be tired. Try waking up your spouse every 10 minutes tonight and then tommorrow ask them if they are tired!

[BP]

I was refering to this quote from the article:

Sleep apnea - brief episodes when breathing stops during sleep - was not a significant player in excessive daytime sleepiness. This is consistent with prior studies that have reported only weak associations between sleep apnea and excessive daytime sleepiness.

Maybe their wording is faulty, but it says what is says. Probably they should have said, that in the general poplulation sleep apnea has a weak association to eds, but their statement implies apnea doesn't cause eds, when we know that it does.

-BP

[wading thru the muck!]

BP & DCTom,

You've got it right... The conclusion that there is little correlation between OSA and EDS defies logic.

What these studies show is that in a population with EDS, OSA may be less likely the cause than other conditions such as depression or diabetes.

It does not show that a population with OSA is not likely to have EDS.

George45 should definately investigate ALL potential causes of his EDS... it may be that OSA is not the cause in his case.

[Guest]

Main Entry: cor·re·la·tion
Pronunciation: "kor-&-'lA-sh&n, "kär-
Function: noun
Etymology: Medieval Latin correlation-, correlatio, from Latin com- + relation-, relatio relation
1 : the state or relation of being correlated; specifically : a relation existing between phenomena or things or between mathematical or statistical variables which tend to vary, be associated, or occur together in a way not expected on the basis of chance alone <the obviously high positive correlation between scholastic aptitude and college entrance -- J. B. Conant>

In other words, not everyone that has OSA is going to have EXCESSIVE Daytime Sleepiness. AND Not everyone with EDS has OSA!

It does not mean that people with OSA can't have EDS.

Again here is another article stating the same What is causing daytime sleepiness?

Commonly used subjective sleepiness questionnaires (eg, the Epworth Sleepiness Scale) may have poor correlation with the presence or severity of obstructive sleep apnea and with the degree of objective sleepiness (5). For this reason, formal sleep studies (discussed later) are mandatory in suspected cases.

Again, correlation does not mean that it doesn't happen, it just means that it does not happen in a statistical meaningful way.

The conclusion pretty much ties it all together

An MSLT should be performed whenever any identified abnormality on the all-night polysomnogram is not clearly sufficient to explain the extent of daytime symptoms. Obstructive sleep apnea and periodic extremity movements during sleep are very common in asymptomatic patients, so their presence during polysomnography must be interpreted in the entire clinical context. Notably, although a given patient may have depression, depression is not an explanation for true excessive daytime sleepiness. Sleep disorders and depression certainly may coexist, however, and sleepiness may masquerade as or exacerbate depression

[sanctacaris]

It's hard to tell from the study summary just what's going on, but it sounds to me like the statement that sleep apnea "was not a significant player in excessive daytime sleepiness" is a combination of the prosecutor's fallacy [http://en.wikipedia.org/wiki/Prosecutor%27s_fallacy] and imperfect methodology. There's no way they conducted sleep studies on all 16,500 people in their study. Neither did they test them for diabetes or depression--they relied instead on individuals' reports of their diagnoses. For inferences from this approach to be valid, diagnoses need to be accurate, and all conditions must have an equal probability of having been diagnosed. If some condition was regularly underdiagnosed or misdiagnosed it could seriously compromise the study's results. I'd hazard a guess that, since sleep apnea was recently listed as one of the most underdiagnosed serious medical conditions in the US, there was a fair number of undiagnosed apneacs in the study, including people whose apnea was undiagnosed but whose diabetes or depression were (what are two common results of sleep apnea? anyone?)[/url]http://sleepdisorders.about.com/cs/rela ... iadeap.htm).

The "prosecutor's fallacy" part comes into play because almost 9% of the sample had EDS, but only about 3% would be expected to have apnea (I think that's right--about 4% of men and 2% of women), if it really is a representative sample of US adults. Therefore, even if every patient with apnea was correctly diagnosed, and even if every patient with apnea had EDS, 2/3 of the sleepy patients in the study wouldn't have apnea.

Well, that was a rather long-winded rant. I hope it made some sense. And, yes, I clearly haven't figured out how to insert links. Oh, well.