Study: "CPAP machines do not reduce heart attack, strokes"

[chunkyfrog]

Whatever the long term effect of cpap use, I think I will keep on using mine.
The resultant improvement in quantity and quality of my sleep has the direct effect of making me much less grumpy.
Life is far more pleasant for me; and I'm told the same goes for my family.

[billbolton]

Is anyone in this forum knowledgeable about ApneaLink?

See here http://www.resmed.com/au/en/healthcare- ... k-air.html

And here http://www.resmed.com/au/dam/documents/ ... lo_eng.pdf

It's not as exacting as an Polysomnogram study, but devices like Apnealink are widely used globally by clinicians for OSA diagnosis on patients who are unable to take a PGG study for whatever reason.

There has been a very great deal of discussion here on the matter of home diagnosis versus PSG, without any decisive conclusion being reached. Be aware that quite a bit of those discussions involve arguing various aspects of the US healthcare delivery system, which IMO is not really relevant to the efficacy of either method.

[Pneumophile]

Thanks. I've had a quick look and that's what I gleaned. How controversial among sleep docs and sleep researchers is the use of SleepLink vs the full Monty in a scientific study I wonder? I wouldn't know exactly and shall ask my sleep doc when I next see him. Of course in this large international study including sites with no OSA expertise they probably felt that they had no choice. Otherwise they'd have had to have a travelling circus.

So one could consider this a possible weakness of the study yet no attempt was made to address the issue openly in the paper. But in the scheme of things it's probably a minor issue, compliance and overall data quality being the big daddies. As a reviewer I might have asked for more verbiage but it's hardly a show-stopper.

[palerider]

Thanks. I've had a quick look and that's what I gleaned. How controversial among sleep docs and sleep researchers is the use of SleepLink vs the full Monty in a scientific study I wonder? I wouldn't know exactly and shall ask my sleep doc when I next see him. Of course in this large international study including sites with no OSA expertise they probably felt that they had no choice. Otherwise they'd have had to have a travelling circus.

So one could consider this a possible weakness of the study yet no attempt was made to address the issue openly in the paper. But in the scheme of things it's probably a minor issue, compliance and overall data quality being the big daddies. As a reviewer I might have asked for more verbiage but it's hardly a show-stopper.

I don't see why you're so hung up on the screening device that they used to see whether people had apnea or not, something that's a mere pebble in the pyroclastic flow of issues with the 'study'.

[Pneumophile]

I'm not "hung up"' and explained why. Did you read? It is but one aspect of the study and a minor one by comparison. Why bother to post if you're so disinterested?

The significance of the diagnostic device used should be obvious to all but I guess not.

What a bizarre forum this can be at times.

[palerider]

I'm not "hung up"' and explained why. Did you read? It is but one aspect of the study and a minor one by comparison. Why bother to post if you're so disinterested?

The significance of the diagnostic device used should be obvious to all but I guess not..

because I don't understand why you're making such a big deal of the fact that they didn't go into great detail about something that's well documented for anybody that cares to look, that's all. you just keep posting and posting about the apnealink, and it's just a screening device to say whether or not someone has apnea, seems quite immaterial to the point of the study, to me.

It doesn't matter how one is screened, apnealink, watchpat, full PSG, one of the many other screening devices. The only thing that matters is "does this person have OSA or not"... doesn't affect the outcome of the study in the slightest, since what *does* matter is adequate use of cpap *after screening*.

What a bizarre forum this can be at times.

yeah, no kidding.

[DreamStalker]

I'm not "hung up"' and explained why. Did you read? It is but one aspect of the study and a minor one by comparison. Why bother to post if you're so disinterested?

The significance of the diagnostic device used should be obvious to all but I guess not.

What a bizarre forum this can be at times.

He doesn't read anything Pneumo .... he's just on the forum to whine, complain, and ride everybody's ass (that's why he calls himself assrider or whatever ).

Normally, he'd just kick his house cat, but when he misses, he takes out his aggression on unsuspecting forum members (today it happens to be you ).

[Pneumophile]

Thank you DreamStalker. Look I've got no beef here. Hardly know anything about anyone except Pugsy who is the resident Saint, doesn't take long to find that out. Nothing controversial there . And there are many people here including yourself who clearly know a lot about OSA, certainly more than I, and I learn from them daily. I have my own OSA issues which I'm presently working on. This forum helps. But as should be clear my background is scientific and clinical research - but NOT sleep disorders - so naturally I'm interested in OSA research that gets published and makes claims of broad importance like the present study. Is that unreasonable?
Cheers

p.s. that was witty. We could all do with more of that.

[jnk...]

As a general rule, as I understand it, home sleep tests are acceptable at proving someone should try CPAP, but are incapable of proving someone does NOT have OSA.

I believe that full lab/center diagnostic NPSG followed by full lab/center titration is the only reliable way, scientically speaking, actually to document sleep-breathing issues, confounding sleep issues, and objective positive response to therapy. Everything else is "close enough" for keeping costs down, but not good enough, in my opinion, for scientific conclusions.

I personally consider the fact that they made the decision to fly blind like that to be a key factor in the study crash. Had they had true lab/center squiggly lines on file, they might have had a snowball's chance in wherever of figuring out where they went wrong.

But I realize that CV specialists may occasionally prescribe PAP for issues somewhat unrelated to the reasons sleep docs generally prescribe it. Thus one of the many apples/oranges muddying of the waters in this "study" that is even worse than the mixed metaphors of this sentence.

[Pneumophile]

That was v. helpful and I agree. Of course the authors might respond to the effect that false negatives were not a problem for them in this study (except in getting the study powered). Also, if the false positive rate was zero (i.e. every last subject diagnosed by ApneaLink as OSA would indeed have been diagnosed with OSA per the gold standard) then all recruited subject were appropriate. Whether this is true (or nearly true) or not I have no idea. The issue should have been discussed at least a bit in the paper imo.

If I do contact the lead author with questions this will be one. I'm not sure I can be bothered to be honest.

Later: here's an ApneaLink validation paper
http://www.ncbi.nlm.nih.gov/pmc/article ... .4.387.pdf

Rather a small sample size (59 subjects).
Sensitivity (true positive rate) = 91%
Specificity (true negative rate) = 95%

Specificity is what matters most here - what percentage of subjects were falsely identified as having OSA? 95% specificity implies a 5% false positive rate and is not at all bad but isn't perfect. What effect false positives had in this study is anyone"s guess.

Specificity = True Negative / (True Negative + False Positive)

[D. H.]

Yes, a study with at least seven hours of nightly use would be best. I suspect that the results would be remarkably different, as even this researcher suggested that patients who hit the four hour mark do show a reduction in the incidence of stroke.

Furthermore, even if this study should prove correct, the other benefits of CPAP still suggest it is important to use!

[Pneumophile]

D.H.: I agree in all respects, especially your point that their own data are consistent with the hypothesis that a median (or mean) of >/= 7 hours for subjects on study would have resulted in a greater and more significant clinical benefit in the primary analysis (composite CV endpoint). Sadly they didn't - and probably couldn't - do that subset analysis because the data were't available to them.

[chunkyfrog]

And why they chose the parameters they did remains a mystery.

[palerider]

the real question is, why are these people running these studies when they understand the effective treatment of sleep apnea

LESS THAN WE DO!?!?!?!!?!

[jnk...]

I have very deep respect for science. And I applaud putting the time, effort, and money into researching PAP on larger scales and how it relates to particular subsets of patients with serious comorbidities. I believe a lot of people's hearts (no pun intended) were in the right place. There is even a certain perspective on this study (involving a purely science-geek angle and a lot of squinting) where the whole thing makes an odd sort of sense.

But I hate it. I really hate it.