Does Treating Sleep Apnea With CPAP Improve Cardiovascular Outcomes or Lower Risk of Atrial Fibrillation?

Despite the widespread belief that obstructive sleep apnea (OSA) causes cardiovascular events like strokes and heart attacks there is actually no good evidence that treating OSA lowers the risk of such cardiovascular outcomes.

Observational data showing that OSA is associated with cardiovascular outcomes outcomes like atrial fibrillation, stroke, CV death and myocardial infarction have been utilized by the sleep apnea academic-industrial complex (in ways very similar to the omega-fatty acid (OMFA ) academic-industrial complex) to market the need for sleep apnea diagnosis and treatment.

However, as we saw in the OMFA world, causality can only be proven with a randomized trial of effective therapy of the disease (given that there is no way to randomize patients to having OSA or not having it.) The most widely prescribed and effective therapy for OSA is continuous positive airway pressure (CPAP).

Healthy User Bias is a major confounder of most CPAP and all observational studies as noted at ClinicalCorrelations

Observational studies have demonstrated that among patients with OSA, CPAP is associated with a lower incidence of fatal and nonfatal cardiovascular events. A recent meta-analysis of observational studies corroborated these findings, noting a hazard ratio (HR) of 0.37 (95% CI, 0.16 to 0.54) for cardiovascular mortality in CPAP treated patients compared to untreated patients. However, these studies are marred by their lack of randomization. Therefore, the patients compliant with CPAP may have enjoyed their cardiovascular benefit from any number of downstream effects of their general aptitude towards making healthy lifestyle choices (the healthy user bias) rather than from CPAP alone.

A recent draft document on CPAP therapy for OSA from the Agency for Healthcare Research and Quality of the U.S. Department of Health and Human Services outlines some of the major unresolved questions:

Obstructive sleep apnea (OSA) is a disorder characterized by periods of airflow cessation (apnea) or reduced airflow (hypopnea) during sleep. The diagnosis and severity of OSA, and response to therapy, are typically assessed using the apnea-hypopnea index (AHI). However, no standard definition of this measure exists, and whether AHI (and associated measures) are valid surrogate measure of clinical outcomes is unknown. OSA is commonly treated with the use of continuous positive airway pressure (CPAP) devices during sleep. The efficacy of CPAP, including for Food and Drug Administration (FDA) clearance/approval, has been based on changes in AHI, but the long-term effect of CPAP on clinical outcomes and the role of disease severity (as measured by AHI) or sleepiness symptoms on the putative effect of CPAP are unclear.

After looking at 47 studies on this question, the AHRQ review concluded that there was no evidence to support the idea that CPAP treatment lowers “clinically important outcomes.”

The published evidence mostly does not support that CPAP prescription affects long-term, clinically important outcomes. Specifically, with low SoE (standard of evidence) RCTs do not demonstrate that CPAP affects all-cause mortality, various CV outcomes, clinically important changes in psychosocial measures, or other clinically important outcomes. 

And there isn’t evidence that CPAP treatment of OSA influences individual aspects of CV disease, including atrial fibrillation, which totally counters the mantra that sleep centers and atrial fibrillation experts have been spouting for years:

Insufficient evidence exists regarding effect of CPAP on the risk of transient ischemic attack, angina, coronary artery revascularization, congestive heart failure, and atrial fibrillation.

In fact, the two randomized controlled trials (RCTs) that report atrial fibrillation came to opposite conclusions with one showing it lowered risk and the other one showing that CPAP raised the risk of developing atrial fibrillation!

Pretty much everything. you thought would be helped by CPAP treatment has not been proven says the AHRQ

Regarding other assessed outcomes, CPAP does not affect the risk of driving accidents or the risk of incident diabetes (both low SoE). CPAP does not result in clinically significant changes in depression or anxiety scores, executive cognitive function measures, or nonspecific quality of life measures (all low SoE). There is insufficient evidence regarding the effect of CPAP on incident hypertension, functional status measures, male or female sexual function, or days of work missed.

There is a clear and obvious way to prove that diagnosing OSA matters (beyond improving daytime sleep and snoring) and that OSA is a life-threatening disease and that is to randomize patients diagnosed with OSA to treatment with effective therapy (CPAP) and several of these have been performed. Unfortunately for the OSA business, the results of these RCTs do not show a benefit of therapy, consequently sleep experts/centers and businesses that sell OSA diagnostic and therapeutic equipment tend to gloss over, dismiss or ignore these data.

Clinical Correlations does a good job of summarizing the methods and outcomes of the major randomized trials for those interested and they concluded:

Recurrent patterns emerge from these data reviewed here. Typical use of CPAP does not ameliorate the risks of fatal and nonfatal cardiovascular events in patients with OSA, though it may reduce symptoms of daytime sleepiness and snoring. Subgroup analyses of patients wearing CPAP over 4 hours per night suggest that CPAP may lower cardiovascular events; however, these findings are subject to significant bias

Post-hoc subgroup analyses like the association of CPAP usage >4 hours with lower events cannot be used to prove causality; they should serve as hypothesis-generating. However, if your business is diagnosing and treating sleep apnea you are highly biased to cherry-pick the available studies.

Thus, although the non biased writers of the main analysis section at Clinical Correlations came to the proper conclusion: no benefit, a pulmonary/sleep medicine MD “commentary” addition concluded the exact opposite:

As multiple studies have shown, treatment of OSA with CPAP has numerous cardiovascular benefits, including arrhythmia control and prevention of recurrence, improved glycemic control, and reduction of the risk for stroke and MI.

This pro-sleep apnea treatment commentary focused on the CPAP>4 hour subgroup analysis without admitting the severe bias this introduces and without discussing how common this is.

Such cherry-picking of the data is common in marketing and surprisingly throughout peer-reviewed articles in major journals. Social and news media summaries of such articles invariably eliminate discussion of the weakness of the observational database supporting the AF/OSA connection and ignore the lack of support from RCTs.

Screening and Marketing of OSA

Here’s an online heading and opening story about a study that found a huge percentage of AF patients had OSA.

Screening for OSA is often done by questionnaires such as STOP-BANG or the Epworth Sleepiness Scale. STOP-BANG asks questions about snoring, sleepiness, observed apnea or choking and hypertension plus 4 clinical attributes (hypertension, obesity, age, neck size, and gender.) and classifies patients as low, intermediate or high risk. It has a high sensitivity of 90% but a very low specificity of 36%. This means that 2/3 of individuals who take this screening who don’t have OSA when tested formally will be told they may have OSA.

I just took the STOP-BANG questionnaire and scored 4 (age 50 years, hypertension, fatigued during the day, and male). This was classified as “high risk” for OSA.

A male over age 55 already has 2 points on the score and since 3 points is considered “high risk of OSA” and all wives tell me their husbands snore, every man over age 55 is going to be identified at high risk.

To summarize and answer the question in my title:

Despite numerous flawed observational studies suggesting an association between sleep apnea and cardiovascular outcomes including atrial fibrillation the gold standard, high-quality RCT data do not clearly show that treatment of sleep apnea with CPAP improves cardiovascular outcomes.

Until good scientific evidence proves that treatment of OSA really does save lives, reduces heart failure, atrial fibrillation, or other important cardiovascular outcomes, widespread screening and marketing for the diagnosis and treatment of OSA other than reducing snoring and daytime sleepiness should cease.

Somnoapoplectically Yours,



18 thoughts on “Does Treating Sleep Apnea With CPAP Improve Cardiovascular Outcomes or Lower Risk of Atrial Fibrillation?”

  1. I used CPAP for about 10 years and it definitely changed my life for the better. I was very sleep deprived. After the first night using it I slept soundly for the first time in many years. I was even groggy! I felt human again. During Covid I decided to lose weight due to the benefit of surviving. I lost 30 pounds going from 167 pounds (BMI 27.8) to 137 pounds (BMI 22.8). After a couple of years I noticed that during the rare times that I forgot my mask, I still slept well. I finally repeated the sleep study and it showed no sleep apnea! Seriously, if my doctor would have suggested that I lose weight to control the sleep apnea I would have done it. I wasn’t considered obese so it didn’t dawn on me that just being overweight could be causing the sleep apnea. Lesson learned!

  2. Dr. Pearson, your latest newsletter directed me to this article. I was diagnosed with OSA about 15 years ago, got driven crazy attempting to use a CPAP, had some luck with a mandibular-advancement device, all while thinking that the sleep-doc’s reasoning for my diagnosis seemed flawed to this sleep-medicine newbie. Several years later the oral device started causing jaw pain, then it broke. I then contacted an out-of-town doctor who was willing to arrange to have equipment sent to my home so I could re-test without all of the sleep-disrupting factors of a lab study. I easily passed–no OSA. To say that I’m skeptical of (and frankly, pissed-off at) the “sleep apnea academic-industrial complex,” as you put it, is an understatement.

  3. I would suggest that sleep studies should replicate how someone sleeps. They wire you up with you on your back and you end up sleeping in that position, the position most likely to cause sleep apnea. I will get retested lying on my side as I normally sleep. If you are going in for a sleep study I suggest you sleep on your side.

  4. The NHS website does not mention sleep apnea as a cause of AFIB. I feel no difference if I use it or not. I have been very compliant in using my CPAP and now have two fillings in my mouth due to the CPAP drying out my mouth and causing tooth decay. The sleep study was said to have shown my blood oxygen level as low as 85%. I have found a solution for the dry mouth but I don’t know how long I’m going to keep using the CPAP.

  5. I love the discussion. If folks are interested in sleep’s reply to the AHRQ’s draft it can be found on the AASM website:

    Let me clear in that I house a bias, but I did want to share a counterpoint with as little coloring as possible.

    The difficulties of gathering a controlled randomized trial are difficult, as stated by TSC. I agree there are numerous variables that could lead the outcome to a false outcome, or as suggested a false positive. I believe it is also important to state that 47 people is a very, very small sample size for the AHRQ to make such a determination of “no evidence to support the idea that CPAP treatment lowers “clinically important outcomes”. This outcome and proclamation remind me of when the US Dept. of Health stated a few years ago that there is no need to floss your teeth because they could find no convincing evidence that it promotes plaque removal or prevents tooth decay. I would advise us to all ask our dentist if we should, or if we shouldn’t. Just because the data on a small study with inherent flaws isn’t supportive, doesn’t mean it is wrong. Put another way “Unproven is unproven, not disproven”

  6. It seems fairly clear that some users of CPAP have benefit and that some don’t. RCTs might be able to differentiate.
    For many people the throat’s relaxed muscle tone which is induced by sleep is the very culprit that ruins that sleep.
    Sleeping on one’s back, one’s tongue lolls onto the soft palate and back of throat, closing the airway. The lax tissues of nostrils either close or congest due to gravity when sleeping on one’s side.

    Inflating the whole airway with CPAP is only one way to open it.
    There are dental mandibular advancement devices to keep that tongue away from the back.
    There are suction tongue traps that pull it forward.
    There are soft palate surgeries that remove “excess” tissue.
    There are soft palate surgeries that stiffen it.
    There is even a surgery that moves the whole lower half of one’s face forward, away from the throat’s back: Maxillomandibular Advancement. Speak of desperate measures!

    I perceived CPAP to be a “threat”. The greater pressure opening my airway produced the sensation of not being able to breathe OUT – as much a feeling of suffocation as the sensation of not being able to breathe IN.
    It seemed to me that the head of my local hospital’s sleep clinic was not the person to seek advice from. He used a nasal CPAP mask and taped his mouth shut. Every night.

    I tried the dental device. Excess salivation and an hour or so in mornings to re-align my dental occlusion. Otherwise just OKish for sleep.

    Then I came across the research article that introduced degrees of nasal airway restriction in otherwise healthy young volunteers. The more restriction, the greater the incidence of snoring over time and, ultimately, apnea. Reversing the restriction reversed the negative effects.

    So, now I use those stiff plastic stick-on strips for the nose that help you “breathe right” to keep my elderly lax nostrils open at night.
    And I sleep on my side. Yes, you can train yourself to do that.
    It works. For me. Every night. Perhaps not for everyone. I passed my sleep study on strips alone with flying colors.
    Do an RCT??

  7. CPAP therapy would be a lot more effective if masks were made to actually fit the patient’s face. As they are, they tend to leak, and trying to adjust the mask in the middle of the night just wakes one up even more. With 3-D printing technology, it should be financially feasible to create such masks from either photos of the patient’s face or some type of mask something like the ones dentists use for proper fits of dental devices.
    Jane Millar

  8. Bravo!! I have said for the last decades that sleep medicine has a lot of “snake oil”, is too much money oriented, pushed for a relationship with cardiovascular problems using and abusing of the fact that correlation does not prove causality. Great repport Skeptical Dr.

  9. I agree with your recommendation for the industry to cease promising/claiming what it can’t scientifically prove. That said, I used to sleep very poorly, getting up frequently throughout the night, in addition to bothering (and sometimes scaring) my wife with my snoring and long periods where I didn’t appear to be breathing. I would be tired all day and had difficulty staying awake while driving, while in meetings, or sitting at my desk at work. Since I’ve been using a CPAP (6+ hours per night since 2014), those issues have gone away. Additionally, I have high blood pressure, and controlling it became much easier since 2014. Not scientific, but good enough for me to keep using it. I also believe regularly getting good, uninterrupted sleep (which the CPAP allows me) has its own set of benefits for long term health. Solid scientific proof or no, I’ll keep using mine. And I know you are not recommending that anyone stop using a CPAP, just that we understand what proof (or the lack thereof) exists pertaining to the industry’s claims, which I very much appreciate! Thank you!

    • Mark,
      I have seen CPAP work wonder for many of my patients with daytime sleepiness. I’ve also seen lots of patients who have been driven to the brink of insanity trying to use CPAP machines that were prescribed for OSA diagnosed after spouse complained of snoring and who have been told CPAP will save their lives.
      I’m really happy for those patients like you who have greatly benefited from the device and are able to wear it >4 hours nightly
      Dr P

      • Is there data that shows other treatment forms for OSA ie. surgery or oral devices are as good as CPAP? Might this ‘brink of insanity’ cohort benefit from other less cumbersome solutions

  10. Very on-point for my concerns of the last several years reading the headlines about OSA and possible to probable to “proven” links to physiological events, syndromes and diseases.

    My wife regularly shoves me off my back to stop snoring, and reports that I sometimes gasp/snort loud enough for her to hear from several rooms away. I know that I suffer from allergies and post nasal drip bad enough to affect my airway, and have been wondering about this whole OSA testing and CPAP topic for several years now.

    Your reporting will help me to sleep more soundly (and with my wife’s continued help – silently).

    • CPAP has helped me with allergies due to the filtration of air the CPAP provides. No more waking up gasping for air.

  11. One more thing, we should keep in mind just because the studies don’t prove benefit, doesn’t mean there isn’t benefit. JTBF

    • Amen. I hope that this article does not discourage persons diagnosed with OSA to discontinue usage as there are other benefits to CPAP treatment beyond cardiovascular such as brain health. It doesn’t take a double blind placebo controlled study to understand that a lack of oxygen to the brain can be a problem.

      • Is there evidence that people diagnosed with OSA commonly have a (complete?) “lack” of brain oxygenation. This would likely have obvious immediate consequences.

  12. Once again, TSC rocks my complacent world of assumptions, this time on the benefit of CPAP in treating OSA. I scored 5.5 on the STOPBANG test (gave myself a half point for snoring not quite loud enough to be heard through a door). I used CPAP for a few years and my wife did report HER sleep was better but it had no effect on my hypertension (darn) and daytime somnolence, nor for that matter PVCs. On a separate matter, I really appreciated learning about Clinical Correlations! Subscribed. Thank you.

  13. Another excellent post. I also scored 4-5, yet I don’t believe that I have OSA. I did have intermittent atrial fibrillation that was eliminated with a 5 hour ablation procedure. I continue to sleep like a baby!


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