As some of you may have seen in my earlier thread, I was recently self-diagnosed with OSA and have been trying to find the right PAP settings. I've learned a lot here and on other forums.
One of the things I'm not clear on is how to assess treatment efficacy. Broadly speaking, I understand that the goals are to feel better and to be healthier, but what I remain uncertain about is how to assess whether those goals have been achieved.
For one thing, I didn't feel terrible prior to PAP. I do feel better since starting PAP, but I'm not sure how much better I am supposed to feel. I've never had terrible daytime somnolence or other really severe symptoms.
I'm a physician and have been reading the medical literature, and there seems to be no real evidence based consensus about how to judge the adequacy of treatment. In particular, the type of data we review here in the forum, as reported by our machines, seems not to be of primary consideration amongst those who publish in reputable journals in the field.
UpToDate, a commonly used physician reference for evidence-based medicine states the following about assessing treatment efficacy (authors are Meir H Kryger, MD, FRCPC, Professor of Medicine, Yale University; and Atul Malhotra, MD, Professor of Medicine, University of California, San Diego):
As you can see, there is nothing there about looking at the data from user PAP machines. Furthermore, there is no recommendation to look at any measured data to gauge treatment efficacy unless symptoms remain present.Once any side effects of the positive airway pressure are successfully managed and the patient is adhering to the therapy, the patient should be asked whether the symptoms of OSA have resolved. In addition, objective data on compliance and effectiveness can be downloaded from the patient's device and reviewed, although studies on the accuracy of the information are mixed. An objective sleep evaluation is generally unnecessary if the symptoms of OSA have resolved, but repeat testing is indicated for patients who do not improve or who have recurrent or persistent symptoms such as daytime sleepiness . Objective testing may consist of polysomnography or type 3 home sleep apnea testing (HSAT) with concurrent CPAP use. (See "Home sleep apnea testing for obstructive sleep apnea in adults" and "Adherence with continuous positive airway pressure (CPAP)", section on 'Identification'.)
The purpose of such testing is to help the clinician determine the reason for the treatment failure. Possible causes of treatment failure include nonadherence or suboptimal adherence, weight gain, an inappropriate level of prescribed positive pressure, or an additional disorder causing sleepiness (eg, narcolepsy) that may require alterations in the therapeutic regimen. A review of medications should also be undertaken since many drugs may lead to sleepiness. Inadequate sleep time may also negate the expected effects from treatment of OSA.
This letter to the editor titled "The SLEEP GOAL as a success criteria in obstructive sleep apnea therapy" offers an interesting perspective , IMO: https://link.springer.com/article/10.10 ... 016-3944-2
For someone like me who feels "better" and has a user machine-reported AHI under 5, there seems to be forum consensus (in multiple forums) that using higher pressure settings to get the AHI even lower is worthwhile. From what I can find in the medical literature, I am not seeing evidence for such an approach. On the one hand, the health benefits of lowering the AHI further — even if we assume that the machine is correctly reporting AHI — seem to be uncertain. On the other hand, the long-term consequences of using higher pressures also seem to be uncertain.There is a mountain of evidence showing how the AHI can vary from night to night, vary from laboratory to laboratory, from various nasal thermistor to pressure transducers, and AHI can vary based on the different definitions of hypopnea used in different laboratories and software [6, 7, 8, 9, 10, 11, 12, 13, 14]. The contemporary reliance on AHI as generally the only outcome measure assessed in research programs is not in line with many other aspects of medicine that are becoming patient centered as opposed to test centered [6, 7, 8, 9, 10, 11, 12, 13, 14].
To give a simple example, if we assume that my symptoms are well controlled, is it more desirable for me to use CPAP 14 with an AHI of 0 (data averaged over multiple days of therapy) or CPAP 10 with an AHI of 4? As far as I can tell, we are lacking high quality data to support one answer or the other. That is without even considering all the other measurable parameters other than AHI, which as xxyzx pointed out, may be highly relevant to gauging treatment response.