This transcript has been edited for clarity. For more episodes, download the Medscape app or subscribe to the podcast on Apple Podcasts, Spotify, or your preferred podcast provider.
Marwah Abdalla, MD, MPH: Hello. I'm Dr Marwah Abdalla. Welcome to the Medscape InDiscussion podcast series on secondary hypertension. Today's episode focuses on sleep apnea, one of the most common and potentially reversible secondary causes of hypertension. Obstructive sleep apnea (OSA) is highly prevalent in patients with resistant or difficult-to-control blood pressure, yet it remains underdiagnosed in routine practice.
In this episode, we'll discuss when to suspect sleep apnea, how to approach screening and diagnosis, what to expect from treatment, and how it fits into comprehensive hypertension management.
First, let me introduce my guest, Dr Susan Redline. Dr Redline is the Peter C. Farrell Professor of Sleep Medicine and professor of epidemiology at the Harvard T.H. Chan School of Public Health. She's also the senior physician in the Division of Sleep and Circadian Disorders in the Department of Medicine at Brigham and Women's Hospital. Dr Redline, welcome to the Medscape InDiscussion: Secondary Hypertension podcast.
Susan Redline, MD, MPH: Thank you for having me. I'm delighted to be here today.
Abdalla: Sleep apnea is mentioned in every major hypertension guideline as a secondary cause of hypertension. But in practice, there's still a lot of uncertainty around how often it's actually contributing and how aggressive clinicians should be in looking for it. Among patients with hypertension, particularly those with resistant hypertension, how common is OSA?
Redline: Great question. They are co-travelers. In fact, approximately 30%-50% of patients with hypertension have OSA, but as many as 80% of those with resistant hypertension have sleep apnea.
Abdalla: Wow. So given how common it is, why do you think sleep apnea continues to be underdiagnosed, even though clinician awareness has clearly increased over time?
Redline: That is a complicated but important question, and it likely reflects multiple factors. First, patients themselves don't often connect symptoms of OSA, like snoring, which actually some people consider normal or even a sign of being a strong sleeper, or symptoms of sleepiness, which often come on gradually. So people come to accept that that's their usual state with a treatable health condition. Second, clinicians are busy — you know that. They’re often not trained to take a sleep history. The available sleep screening devices are limited, and with scant time, clinicians often prioritize the most acute problems facing them at any given encounter. Third, in some areas, it's challenging to refer to sleep specialists, especially in underserved areas.
And then finally, up until recently, sleep apnea was considered to be treated only with CPAP (continuous positive airway pressure) as an option, and many patients and clinicians thought that CPAP would be their only choice if, in fact, a diagnosis was made, or were reluctant to go down that pathway.
Abdalla: Are there particular patient populations where you think clinicians most underestimate the likelihood that sleep apnea is contributing to their high blood pressure?
Redline: Absolutely. There are two groups I would be concerned about. Population-based data indicate that sleep apnea is particularly underestimated among individuals who identify as being from racial or ethnic minority backgrounds. Our own work in the Multi-Ethnic Study of Atherosclerosis and the Hispanic Community Health Study indicates that as few as 4%-5% of study participants who were found on our research studies to have severe sleep apnea actually had a history of being diagnosed with sleep apnea. We know that the level of severe sleep apnea does confer an increased risk for hypertension and poorly controlled hypertension. The failure to diagnose severe sleep apnea, especially in Black Americans, a group at marked increased risk for hypertensive-related health problems, is a particular concern.
The second group where underdiagnosis is common is generally women. Women often present with features of sleep apnea that differ from men's. For example, they may report fatigue rather than sleepiness. They may be unaware of their own snoring, maybe because they don't have an astute bed partner, and they often have comorbid insomnia that presents with frequent awakenings, which may lead to different diagnoses other than sleep apnea. But what's interesting is that the combination of OSA and insomnia now is recognized as its own entity, called COMISA (comorbid insomnia and sleep apnea), and that is a diagnosis associated with a marked increased risk for both hypertension and mortality compared to either condition alone. And that condition is one that you need to have a high level of alertness to in women. But again, the OSA part is underrecognized in women.
Abdalla: Thank you for highlighting that. I think you are also talking about sleep-related behaviors, and other sleep disorders and conditions that are really important. Let's talk about how we actually identify sleep apnea in practice. How helpful do you find screening questionnaires like the STOP-Bang or the Epworth Sleepiness Scale in routine clinical care? And when do you think they can be misleading?
Redline: Great question. They clearly have a role. For one, they are a relatively simple way to alert the patient and the provider to the need to consider OSA. But every tool available has its own limitations, and we need to really recognize them. And it's not only a limitation, but even in some cases a bias.
For example, to get increased points for the STOP-Bang, you get a point if you're a man, you get a point if you have a larger neck circumference. Many women, if you don't directly measure neck circumference, don't know what their neck circumference is. We don't buy our shirts based on our collar sizes.
And as I mentioned, women are not necessarily going to report snoring and sleepiness to the extent men will, but they may rather report fatigue and insomnia-like symptoms. So the STOP-Bang may systematically underestimate sleep apnea in women.
The Epworth Sleepiness Scale only looks at one symptom: sleepiness. And that's very nonspecific. It could be caused by many other conditions, notably insufficient sleep, not spending enough time in bed, or having other reasons for not getting that 7-8 hours of sleep that we know Life's Essential 8 tells us we need to get, as part of cardiovascular disease prevention. The Epworth is also known to perform less well in women and in older populations; the psychometrics are weaker.
Abdalla: How do you think clinicians should start to think about home sleep testing vs in-lab polysomnography?
Redline: Home sleep tests play a huge role because they're convenient, accessible, measure people in their own home environment, where they may be more comfortable, and get them into a deeper, more representative sleep. And if the tests are positive, they're really helpful.
However, there are cases where they may underestimate sleep apnea, especially in groups that may have more subtle periods of obstruction. We call that hypopnea rather than complete apnea or complete cessations of breathing, and these are people who may arouse at night rather than have a deep desaturation, because many devices don't directly measure those arousals.
Also, in an overnight sleep study that measures EEG, we could determine how much sleep apnea occurs in REM sleep, rapid eye movement sleep, vs non-REM sleep. In many of the home studies, we can't do that. And we know, again, that there are groups, like women, where the sleep apnea may be more severe in REM sleep, and that REM apnea-hypopnea index (AHI) itself may predict blood pressure even better than the total AHI.
Abdalla: Obviously, there are more people being able to access commercially available home sleep studies that they may order via the internet. For patients who bring in results from these commercially available sleep studies, how should clinicians interpret those results?
Redline: As always, we start with the patient, their symptoms, and their medical history, not the test. So everything has to be done in that context. And even as we look at any test result, we are increasingly aware that any single number from a single night study, whether it be a home study or even a full polysomnogram, may not well predict any person's typical sleep, their symptoms, or their treatment response.
When we look at the results of home sleep studies, more so even than polysomnography, there's quite a bit of variability. Polysomnography studies have been done for so long that there's clear standardization. It's part of the certification sleep labs have to go through, but even FDA-approved home sleep apnea studies may measure a wide variety of different sensors and use all different types of software. Some are just much more accurate than others. I think you need to be aware of and talk to your local sleep specialist about how good those specific commercial tests are that you're seeing, and also whether, when you see the report, there's some indication of the quality of the test. In particular, you want to see that the test captured at least 4 or 5 hours of sleep and wasn't just based on a smaller window.
In summary, I would really carefully consider how well the findings align with my patient's symptoms and medical history. If they align well and the information is sufficient to proceed with treatment… But also note that when a patient brings you a test from the outside, any given insurer may or may not require additional testing. Insurance is very complicated these days.
On the other hand, if the test doesn't align with the symptoms — base symptoms — and medical history, I would consider additional testing, with the help of a local sleep specialist who can hopefully provide a transparent report of how the testing was done and an interpretation of how likely it was as being a representative study for that patient.
Abdalla: Fantastic. I love the practical advice. I think it's really important to highlight engagement with the local sleep specialist to understand how to use these tools appropriately. I want to move to: Once a diagnosis is made, what should clinicians realistically expect CPAP therapy to do for high blood pressure?
Redline: As you know, hypertension itself is probably quite heterogeneous, with many risk factors contributing to someone's blood pressure profile. I think we're still not completely aware of — or we haven't figured out how to identify, maybe — that group of people with sleep apnea, where the sleep apnea plays the predominant role.
So when we look at all comers, we see that CPAP reduces blood pressure by about 2-3 mm Hg on average, but there's a tremendous variation. Some people with severe sleep apnea, who are treated and adherent with CPAP, especially those with resistant hypertension, may have reductions as much as 9-10 mm Hg. We also know that what we measure with a random clinic blood pressure may not reflect elevations in blood pressure over the 24-hour period, and there may be larger reductions using a 24-hour blood pressure measurement, especially the nocturnal blood pressure measurement.
Abdalla: As you and I both know, not every patient tolerates CPAP or wants to use CPAP. I'd love it if you could talk a little bit more broadly about adjunctive therapies and when you consider them, such as mandibular advancement devices and hypoglossal nerve stimulation. Any other approaches? How should clinicians think about these options? And educate us about any effect they may or may not have on high blood pressure.
Redline: I love this question because this is one of the most exciting times to be offering treatment to patients with sleep apnea, because it's no longer just CPAP; there are growing numbers and types of treatment. There are multiple devices and even multiple medications, even outside of the GLP-1 therapies, that are under evaluation now.
So we do have real choices, and that really underscores the need to understand which treatments may be best for which patients and which treatments may be most acceptable or aligned with your patient's values. Shared decision-making now really comes into play. Selecting which treatment, and in some cases, combinations of sequences of treatment, needs to reflect personal preference. For example, some patients are reluctant to use medications, especially those with certain profiles of side effects, and would prefer a device; while others may prefer medications and want nothing to do with a machine that's left at their bedside or a hypoglossal nerve stimulation device that will require a surgical procedure. There's also, again, the need to think about personalizing the therapy to the patient's other comorbidities, including obesity. So some therapies — obviously, the GLP-1 medications — are specifically for people who are obese. And now we're also learning that sleep apnea, like hypertension, isn't one disease but a manifestation of multiple different risk factors that relate to different degrees of propensity for a collapsible airway vs an unstable airway vs a narrow anatomic airway. And we have ways to better phenotype these types of sleep apnea; different therapies may work better or worse, depending on that endophenotype.
For example, a woman who has a relatively low AHI but has symptoms of fatigue, disrupted sleep, and so forth, with a BMI of less than 30, and a sleep study that shows relatively short hypopneas — and short hypopneas may indicate a propensity to arouse frequently at night — may do better with a mandibular advancement device than a CPAP.
On the other hand, a woman with a higher AHI, say of 30, a BMI of 40, may do very well with a GLP-1. Another scenario is a male with a very high AHI of 60 and a BMI of 30, who is very sleepy. For that sleepy phenotype male, CPAP may be the ideal therapy for that person, whose sleepiness is likely to respond to CPAP, and then there will be motivation to use the device.
Abdalla: I'm glad you brought up the different phenotypes and the idea of precision medicine. It's interesting as a clinician when you walk into the room. I literally just saw a patient a few minutes before we started talking. With OSA, the only thing offered was CPAP. But he was definitely someone who had taken the time to research his own illnesses and was highly educated and had lots of questions about the medications. I'd love to get some thoughts from you because of the increasing use of the GLP-1s and the dual GLP-1/GIP therapies that we're seeing for weight loss. How should we be thinking about the role of these medications in sleep apnea and hypertension management?
Redline: Very exciting, and as I respond to you, I want to mention that I have consulted for two companies that are testing or actually selling GLP-1 drugs for sleep apnea. But, having said that, I feel very confident that there is a clear consensus that this is a very exciting time and an exciting class of medications because of the evidence that they are quite effective at reducing the severity of sleep apnea when we measure our sort of typical metric, which is the AHI, as well as quantify the overnight hypoxemia. And in fact, both of those measures in studies have been improved by 50% or more, and there's evidence that these medications can improve outcomes important to patients, like sleepiness and sleep disturbances.
As you know, they are known even apart from sleep apnea to have many positive cardiometabolic effects. And in the context of sleep apnea, they may result in fairly dramatic reductions, particularly in systolic blood pressure. Interestingly, when you try to tease out how much of the improvement in blood pressure associated with these drugs are attributable to the improvement of sleep vs the improvement in weight, the statistical model suggests most of that improvement is due to weight loss, actually, but there is some incremental, mediation, or explanatory power from improvement of those metrics of sleep apnea too. So these medications, I think, should be very attractive for people who are clearly obese, in whom the goal is to not only improve their sleep quality — these overnight stresses that their body is experiencing from repetitively stopping breathing at night and becoming hypoxic — but also to improve their multiple cardiometabolic outcomes.
Abdalla: Are there specific considerations that clinicians should be mindful of when integrating these therapies into care and discussing them with patients?
Redline: Clearly, we're still learning about how to make those choices. I do want to repeat that shared decision-making is important. I think it's also quite important that, as we are using more sophisticated medications, even the sleep specialist, for example, needs to be working with metabolic experts as well, and people who understand how to titrate and monitor for side effects.
The issue is that these can be complicated to administer, and some people do get significant side effects, although they often can be managed well with expert care. So it's important to really understand the side-effect profiles and ensure that the patient has access to care and is committed to a long-term program of weight loss and taking these medications.
These medications, as far as I understand, are used lifelong. So they're not a cure, per se, and there are still ongoing cost and access issues as well. The other contextual things that really influence the safety, the ability to adhere, the ability to embrace a chronic therapy are what we're talking about, and they also relate to social situations, level of family support, work schedule, stability of the household, and, unfortunately, even the patient's insurance.
Abdalla: All really important points that I think we also need to make sure our patients understand, so, thank you. I want to switch briefly now to hospitalized patients. Many hospitalized patients present with features that strongly suggest sleep apnea, yet, they often leave the hospital without a diagnosis and it can be difficult to ensure timely outpatient testing after discharge. How should clinicians think about the hospital encounter, including, as a starting point, for outpatient evaluation?
Redline: That's also such an important area, and there's been a lot of discussion. I think you're hinting that this is an opportune time; you have a bed, you potentially have time with the patient that's not as rushed and includes overnight time.
I would use the time in the inpatient setting during hospitalization to speak about sleep and minimally create a plan for follow-up with a specialist or a sleep study, and begin that whole referral process during or before discharge planning.
However, I would really check to see what pulmonary or sleep services or even respiratory therapy provides in your hospital. Some hospitals, and increasingly so, have the ability to conduct bedside sleep studies during hospitalization. These could be done for two different reasons. In one case, it could be done because it's thought that the severity of the sleep apnea may be directly impacting the problem the patient is being treated for. So there is a real interest in accelerating diagnosis and even initiating treatment in the hospital. But the other rationale is that it's an opportunity to do a sleep study at a time that's convenient for the patient. They're ready and available. And some hospitals have worked that out to be able to do that in the in-hospital setting.
Abdalla: On the other end of the spectrum, we're obviously seeing a rapid growth in wearable devices and AI-based tools aimed at detecting sleep apnea and other sleep disorders at home. How do you see these technologies fitting into clinical care going forward?
Redline: It is a rapidly changing landscape, and I'm afraid anything I say today may be outdated even next week. So keep that in mind. Even for the routine things we do, the way we score sleep studies, for example, we're aware that AI is increasingly being developed to identify sometimes really novel signatures of disease that may, in the future, replace our traditional AHI and so forth. In other cases, AI is being used to replace human scoring, and we have to be aware of how that varies from what we are used to a human doing.
Then there are wearables as well as nearables. Nearables are devices you could put on the wall near your bed, or under or over your mattress, that could be used nightly to pick up sleep-related behaviors.
And their huge advantage is they could collect data over days, if not months. That overcomes a problem that I think we've really minimized over many years; there is indeed a group of people who have a high night-to-night variability in their sleep apnea.
So it allows us diagnostically to overcome limitations of making a judgment just based on a single-night study vs multiple nights. But it also allows us to potentially identify triggers for nights when sleep apnea is worse, or even situations where sleep apnea may be better. For example, give people feedback on how their evening cocktail influenced the severity of their sleep apnea or how their sleep duration the night before influenced the sleep apnea, the subsequent night, or stress levels.
There's even data now that temperature, climate change, and air quality may have an impact on night-to-night severity. So I think that starts giving us a lot of interesting ways to think about how numbers from a sleep study are static, but it's something that may vary, and those sources of variation might even be targeted in the future.
Abdalla: It seems like these tools are not just screening aids; you're really thinking about them as longitudinal monitoring, and maybe for the discovery of new phenotypes, too.
Redline: They certainly may alert someone, or reinforce to someone — increasing people's own awareness of their sleep apnea symptoms — to have a conversation with their doctor. But many of the wearables that I know of have really been validated to pick up a moderate degree of sleep apnea based on a single AHI.
As we think across the population — women in particular — I do worry that people will be overly reassured, based on their wearable, as well as the fact that wearables may not accurately reflect severity in every situation. So, maybe as a flag, "Hey, let me have a talk with my doctor and decide what more testing I need" is very reasonable. And then once diagnosed, especially once treated, following some of the measures within your own dataset, your own experience, could be useful.
Abdalla: Fantastic. Well, this has been a great conversation. I'd like to ask you for three short key takeaways for clinicians managing hypertension in relation to sleep apnea. What would they be?
Redline: One is that you have more than CPAP at your disposal. The second thing is, when you are deciding on treatment, really embrace the idea of shared decision-making, including patient preferences and your patient's underlying disease characteristics that may influence the likelihood of your patient responding positively to treatment and having both short- and long-term benefits. And three, develop, if possible, a relationship with the sleep specialists in your area and understand the limitations of your institution's or your clinic's screening and diagnostic tools — for example, knowing at what point certain groups, such as women, may or may not be limited by the current set of tools being used.
Abdalla: Thank you, Dr Redline. I always learn so much when talking to you. I really love talking to you and appreciate your perspective and insights. Thank you to our listeners for tuning in. Please take a moment to download the Medscape app to listen to this podcast series on secondary hypertension.
This Dr Marwah Abdalla for the Medscape InDiscussion podcast.
Resources
Secondary Hypertension: Evaluation and Management
Racial/Ethnic Differences in Sleep Disturbances: The Multi-Ethnic Study of Atherosclerosis (MESA)
Comorbid Insomnia and Sleep Apnea: From Research to Clinical Practice
Respiratory Event Index Underestimates Severity of Sleep Apnea Compared to Apnea-Hypopnea Index
Obstructive Sleep Apnea Endophenotypes
Detection of Sleep Apnea Using Wearable AI: Systematic Review and Meta-Analysis
Technologies for Sleep Monitoring at Home: Wearables and Nearables
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Cite this: Secondary Hypertension and Sleep Apnea: Screening, Diagnosis, and Treatment - Medscape - Mar 31, 2026.
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