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Is AHI a good measurement unit?
There are (only) 3 things there is international consensus about when we talk Sleep Apnea.
1. AHI (Apnea Hypopneas events > 10 seconds per hour)
2. SaO2 Desaturations.
3. The full PSG study as the "Gold Standard".
Furthermore, there is international consensus on an AHI scale of severity:
Mild SA = AHI between 5 and 15
Moderate SA = AHI between 15 and 30
Severe SA = AHI > 30
Of course I agree that AHI is a good measuring unit to detect SA. But as with previous measurement of Nocturnal pulse oximetry, I believe that this unit has several shortcomings.
After this measurement unit was introduced, we have got a lot of new knowledge, e.g. about UARS. Most of PSG studies cannot measure this.
Even when we discuss the severity of SA, I am not sure this unit is good. For example, a person with severe SA can have very little or no desaturations, and conversely, a person with very mild SA can have strong desaturations. Corresponding with symptoms. I have also seen new studies that indicate that even AHI <5 can bring severe sleep problems.
I therefore think it is pointless to talk about the severity associated with AHI. I don’t know who and how this scale has been decided, but it is certainly comfortable among some doctors because they can use it for the preparation of guidelines and I have even seen that this scale is used in a simple decision table to determine the severity and the treatment of SA (or maybe the lack of treatment).
IMO There is too much focus on the AHI as the sole determinant of the severity of SA, from Sleep centers, Public health care systems and maybe especially Insurance companies.
I think that we need to look more at the whole person, and all of the symptoms until we have a better measuring unit.
Let me hear your opinion.
Henning
1. AHI (Apnea Hypopneas events > 10 seconds per hour)
2. SaO2 Desaturations.
3. The full PSG study as the "Gold Standard".
Furthermore, there is international consensus on an AHI scale of severity:
Mild SA = AHI between 5 and 15
Moderate SA = AHI between 15 and 30
Severe SA = AHI > 30
Of course I agree that AHI is a good measuring unit to detect SA. But as with previous measurement of Nocturnal pulse oximetry, I believe that this unit has several shortcomings.
After this measurement unit was introduced, we have got a lot of new knowledge, e.g. about UARS. Most of PSG studies cannot measure this.
Even when we discuss the severity of SA, I am not sure this unit is good. For example, a person with severe SA can have very little or no desaturations, and conversely, a person with very mild SA can have strong desaturations. Corresponding with symptoms. I have also seen new studies that indicate that even AHI <5 can bring severe sleep problems.
I therefore think it is pointless to talk about the severity associated with AHI. I don’t know who and how this scale has been decided, but it is certainly comfortable among some doctors because they can use it for the preparation of guidelines and I have even seen that this scale is used in a simple decision table to determine the severity and the treatment of SA (or maybe the lack of treatment).
IMO There is too much focus on the AHI as the sole determinant of the severity of SA, from Sleep centers, Public health care systems and maybe especially Insurance companies.
I think that we need to look more at the whole person, and all of the symptoms until we have a better measuring unit.
Let me hear your opinion.
Henning
Views: 3527
Replies to This Discussion
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Permalink Reply by Henning on
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That means that the AHI depending on definitions can go from very mild to moderate and near to the borderline of severe Sleep Apnea.
So I’m more than ever convinced that the AHI is useless as measurement, also in the light of that UARS is not measured.
I found an interesting article from Lee K. Brown, MD., Sleep Disorders Center, University of New Mexico. He advocates that even very mild sleep apnea (AHI > 0.1) should be treated.
Just look at this sentence:
“Prospective data from the Wisconsin Sleep Cohort have proven an even stronger relationship in terms of 4-year incidence of developing hypertension: compared to subjects with AHI=0, odds ratios (and 95% confidence intervals) for incident hypertension were 1.42 (1.13–1.78) for AHI between 0.1 and 4.9 and 2.03 (1.29 – 3.17) for AHI between 5 and 14.9.”
But there is a lot of other argues in his article.
Here is a link to his article:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2564769
Henning
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Permalink Reply by Mike on
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i just realized i haven't yet dug into this research myself, and that new members might find this thread interesting, so bumping it.
Henning said:That means that the AHI depending on definitions can go from very mild to moderate and near to the borderline of severe Sleep Apnea.
So I’m more than ever convinced that the AHI is useless as measurement, also in the light of that UARS is not measured.
I found an interesting article from Lee K. Brown, MD., Sleep Disorders Center, University of New Mexico. He advocates that even very mild sleep apnea (AHI > 0.1) should be treated.
Just look at this sentence:
“Prospective data from the Wisconsin Sleep Cohort have proven an even stronger relationship in terms of 4-year incidence of developing hypertension: compared to subjects with AHI=0, odds ratios (and 95% confidence intervals) for incident hypertension were 1.42 (1.13–1.78) for AHI between 0.1 and 4.9 and 2.03 (1.29 – 3.17) for AHI between 5 and 14.9.”
But there is a lot of other argues in his article.
Here is a link to his article:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2564769
Henning
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Permalink Reply by Sharon Cheadle on
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I had no idea that AHI is such an outdated measurement. As I have already posted in this forum a good friend of mine is newly diagnosed with sleep apnea. We actually conceived this measurement as very useful and comprehensible.
Sorry to ask the question in this thread but I just have to ask it:
I recently heard something about Provigil as treatment modality for sleep apnea. What are your experiences with this medication? Is it effective? Would really appreciate useful information. thx in advance
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Permalink Reply by RockRpsgt on
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RERAs do not need a drop in desat to count only an arousal and a drop in respiratory effort. It is not the insurance industry on a whole that has turned it's back on RDI, but rather medicare whom has made the decision to go with AHI. It is only natural that the others would follow. Using AHI makes it harder to get approved for PAP treatment. I was taught using both.I have heard an insurance company will except a diagnosis based on RDI if the Dr. will back it up. This brings us back to poor medical education on sleep. Most labs are calculating RERAs into an arousel index and presenting this with the AHI to the insurance companies for qualification. If the lab knows what they are doing no one should get misdiagnosed. or not qualify.
If a sleep lab know theirs stuff then AHI is a great way to determine severity. AHI and pressure setting do have some correlation. If I know a persons AHI I can give you a pretty good range of what their pressure is going to be. I can also tell to a point in how bad of health someone might be in by seeing their AHI. It is a percentage game that is usually correct. No the original intent for AHI is not always a good measurement, but as the industry evolves so to do the people working it. If a sleep tech sees a need for pap therapy it is his/her job to make sure that you get qualified for it. With all that said I would like to see RDI with the Chicago criteria become the gold standard. It would make it easier to treat more people.
Don't even get me started on Home studies.
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Mike, will you be making the Manhattan AWAKE presentation by Dr Rapoport available to use any time soon? It was interesting to note that this is the same Dr Rapoport who debated the usefulness of the AHI w/Dr Colin Sullivan who has been a leader in PAP research and development.
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Permalink Reply by Renee on
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Hello Judy ~
As I am going to have to go to, yet, a 3rd sleep center to try to get help with excessive tiredness, I appreciate your posting this info.
Thank you,
Renee
Judy said:Well, after not being too impressed w/an "accredited" sleep lab I learned: if it is w/in a reasonable distance at all GO TO THE LAB, ask to see the sleeping rooms, talk to the staff and ask questions: do they take self-referrals or is your own doctor's referral needed? do you have a consult w/the doctor BEFORE your sleep evaluation? do you have a consult w/the doctor AFTER your titration if Dx'd w/OSA and BEFORE your equipment order (script) is written? do you have any input into the equipment that will be ordered? who does the scoring? are all of their sleep techs RPSGTs or are some in training? what is the prime specialty of the sleep doctor who will be interpreting and dicating results of your studies? is this doctor a certified sleep specialist? is the sleep doctor averse to your taking an active part in your therapy, will he/she be willing to work w/you as a TEAM? how long does it usually take to get your test results? are you provided w/a copy of just the doctor's dictation or also w/a copy of the full scored data summary report w/condensed graphs? how soon can you expect to receive them? will the doctor go over and explain those results w/you?
And, of course, you want to call your insurance company to ask what sleep centers they are contracted w/and what local DME suppliers they are contracted with.
National Jewish in Colorado and Stanford in California appear to be two of the top sleep centers in the USA. If you have lung problems in addition to plain ole garden variety sleep disorder(s) I'd tend to pick National Jewish as the leading lung center in the country.
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