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We talk with Jordana Cohen, an internal medicine physician, about the importance of accurate blood pressure measurement. With the rise of telehealth and at-home monitoring, ensuring reliable readings is crucial. Jordana discusses concerns regarding device accuracy and introduces the U.S. Blood Pressure Validated Device Listing (VDL) as a solution. Discover how the VDL evaluates and lists clinically accurate devices. Join us for this insightful conversation on improving patient care through accurate blood pressure measurement.

Jordana Cohen is an internal medicine physician.

She discusses her KevinMD article, “How the U.S. blood pressure validated device listing (VDL) ensures accurate readings and revolutionizes hypertension control.”

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Transcript

Kevin Pho: Hi, and welcome to the show. Subscribe at KevinMD.com/podcast, and get CME for this episode by clicking on the CME link in the show notes. Today we welcome Jordy Cohen. She’s a nephrologist. Her KevinMD article is titled “How the U.S. blood pressure validated device listing (VDL) ensures accurate readings and revolutionizes hypertension control.” Jordy, welcome to the show.

Jordana Cohen: Thank you so much for having me.

Kevin Pho: We’ll get to your article in a little bit. First off, briefly share your story and journey to where you are today.

Jordana Cohen: Yeah, so I’m a nephrologist and hypertension specialist, right now at the University of Pennsylvania. I grew up in a medical household. My father was a primary care doctor, a family practice doc. He was in solo practice, and my mother was his only employee. They did not have a single computer in their office for almost the entire duration of their practice. This included when computers became required for many, many forms to be submitted and things like that, and so I was in elementary school doing a lot of things like that.

I grew up in their medical office, and my dad had mercury blood pressure cuffs on the walls in the exam room for decades. He taught me how to check a blood pressure when I was five years old, and he used to lightly smack me on the head if I got a step wrong with the cuff. So I had it in my blood, I think, that I was going to end up obsessed with blood pressure.

I did my training at Rutgers, went to Boston University for residency, and went to Penn for fellowship. Lo and behold, I didn’t realize that it would happen, but I fell in love with blood pressure during nephrology fellowship. So now I lead several trials and other long-term studies related to better managing hypertension, including studies in patients who are frail, multimorbid, and very medically complex, trying to determine if we’re really doing things right or if we can do better.

Kevin Pho: Wonderful. I also went to Boston University for internal medicine residency, so it’s always wonderful to meet a fellow BU alum. When it comes to blood pressure, you’re on the forefront. Tell us, what can we expect next, in the foreseeable future, in primary care?

Jordana Cohen: I think we’re going to be seeing a lot of patients using cuffless blood pressure devices and either telling us or not telling us. Both could be quite challenging and difficult things to manage, because we’ll be getting contacted by patients asking what it means when their devices are buzzing that their blood pressures are elevated when they’re crossing a street and almost get hit by a bus, or doing some other activity that wasn’t intended for having a blood pressure measured.

And I think they may also not tell us they’re doing it, and perhaps make their own decisions and do other things based on the readings they’re obtaining on these devices. So I think it’s got the potential to expand access to blood pressure measurement for many patients, but I’m also quite reticent about some of the potential dangers of these, because they really aren’t well vetted yet.

Kevin Pho: Now, for those nonclinicians listening to this podcast, just in a nutshell, from your experience, why should we care about blood pressure?

Jordana Cohen: Blood pressure is a precursor to, or puts us at enormous risk for, developing stroke, heart attack, worsening kidney function among people who’ve got kidney disease, heart failure, and other major cardiac issues, and it can worsen people’s quality of life because of that. So it’s very important that we learn what our numbers are, that we get identified as having hypertension or elevated blood pressure early, and that we get treated to avoid having these negative outcomes.

Kevin Pho: And patients ask me all the time in the exam room, when they have their own blood pressure devices, what are some ideal numbers they should be looking for?

Jordana Cohen: If you ask the American College of Cardiology and the AHA, the ideal number is less than 130 over 80. But there are some caveats to that. If you’re really low risk and pretty healthy, you really don’t need to start medication per se until your numbers are over 140 over 90. If you’re really high risk, for instance patients I see with chronic kidney disease, who are at an elevated risk of heart disease compared to other folks, then their goal should actually be less than 120 over 80, depending on who you ask and which experts you believe.

Kevin Pho: Wonderful. Let’s talk more about your KevinMD article, titled “How the U.S. blood pressure validated device listing (VDL) ensures accurate readings and revolutionizes hypertension control.” Now, how did your article come together?

Jordana Cohen: Yeah, so a few years back, when I was sort of an advanced nephrology fellow, I started to realize how many blood pressure devices are available, both in doctors’ offices and to the general public, that are completely unvetted. We don’t know whether they’re actually recording an accurate blood pressure, or if they’re wildly off, like 15 or 20 millimeters of mercury off, in many people. So I got involved with several folks who were interested in this, as well as with the American Medical Association, and we all worked together to develop this validated device listing, which is a carefully vetted listing of blood pressure monitors that have actually been appropriately assessed for accuracy.

Kevin Pho: So what goes into that certification?

Jordana Cohen: We require that the companies have an external group, one that doesn’t have any conflict with these companies, performing blood pressure accuracy, or blood pressure validation, studies according to international standards. There are some older international standards that were not very rigorous, and we don’t allow those. We really require the most rigorous of the international standards. The most recent ones were from 2018, and that’s what we’re really encouraging everyone to do.

These standards, in general, require that a blood pressure device be within about five millimeters of mercury of a gold-standard device, one that is either a mercury blood pressure device or one that’s been recently calibrated and recalibrated with a mercury device. The five millimeters of mercury has some room, some wiggle room, but that’s sort of the average, or a very simplified version, of what we’re looking for.

But there are a lot of steps they have to follow. The studies have to have a certain number of individuals across a range of arm circumferences and a range of ages, to make sure the study adequately represents the general public. That’s because these devices only estimate blood pressure based on an algorithm, and that algorithm can be affected by things like arm circumference, and by blood vessel behaviors that can be impacted by things like age. So we really require that we make sure the devices will work across a reasonable range of people.

Kevin Pho: So often I ask my patients to check their blood pressure at home. So now they’re at home, and they’re going on Amazon or some type of CVS or Walgreens, looking for a blood pressure device. What should they be looking for?

Jordana Cohen: Ah, well, they should be going to the website, I think, before they go and purchase one. www.validatebp.org is the website. As I mentioned, it was originally sponsored by the AMA, but now the folks who are coming up with the recommendations for blood pressure devices are an independent review committee. So the AMA doesn’t get any money for it, and it doesn’t sponsor us in any way. We are all physicians who are hypertension specialists checking that these are valid. That is really the best way to know if a device is actually accurate.

Do not look for just an FDA check mark, because FDA clearance, shockingly, doesn’t really mean very much in terms of accuracy. The FDA doesn’t have any jurisdiction over whether blood pressure devices that are being sold, or that claim they’re taking a blood pressure, are actually accurate or actually checking your real blood pressure. When they actually clear a device, it’s not FDA approval; it’s something just called clearance. It’s a 510(k) process, which is about what they do when they’re checking whether a Band-Aid is safe to use. They do ask companies to claim whether a device is accurate or not, and to say, “Oh, yes, we promise we validated it.” But no one is going through these validations and checking to see if they mean anything, or if they’re actually for the device they claim.

Kevin Pho: What are some of the most common reasons why a device wouldn’t be validated? What are some common reasons why that happens?

Jordana Cohen: Yeah, so the reason it wouldn’t be validated is that it’s expensive and hard to run these validation studies. It’s really hard to find the range of individuals that actually have a broad range of blood pressures, range of sizes, range of ages, and things like that. So I understand that it’s the easier road not to perform it. But I think many companies really just check their devices on the engineers and the folks locally who are available to them when they’re developing these devices, or they use old, arcane algorithms from prior devices.

They sort of redress the device and change everything about it: maybe make a more comfortable cuff, make it look flashier, add some Bluetooth. There are certain changes you can make that really wouldn’t be meaningful, but once you make enough changes, it’s a whole different device, and it’s no longer checking things in the same way. In particular, the cuff you use on your arm really matters, because that’s really what’s sensing most of these oscillometric waves that travel through your blood vessels, which estimate the actual blood pressure. So if that cuff has changed in some way and they don’t revalidate the device, it can be really, really grossly inaccurate, and the company doesn’t even realize it, because what they’re thinking about more is how they can market this to more people.

Kevin Pho: Now, in general, what proportion of commercial blood pressure devices aimed toward consumers are, in fact, validated?

Jordana Cohen: Less than 20 percent.

Kevin Pho: Are these devices generally more expensive than ones that aren’t validated?

Jordana Cohen: Dean Picone and several researchers have looked at this really carefully, and they found that the blood pressure devices that are validated were slightly more expensive, maybe about $10 more expensive on average. But it’s not a huge, huge difference. You can still get many outstanding validated devices for less than $40.

Kevin Pho: Now, for those devices that aren’t validated, is there any value to them at all? Are those readings better than nothing, or is simply not getting any readings better?

Jordana Cohen: Yeah, so one thing we’ve learned with the validated device listing that’s been fascinating to me is that many companies don’t publish their validation studies but actually do things right. They actually go through the entire process and do independent validation, but it’s hard to publish the studies, because a lot of journals don’t think it’s particularly interesting to publish another validation study of a blood pressure device. So what we’ve learned is that some of these devices might not be checked off as actually being validated in these general searches, but if we carefully vet them, there are some that truly have been. So we serve as peer reviewers, essentially, at the validated device listing, for devices that haven’t had their validation studies published but actually work.

So what do you do as a consumer, or as a provider, in terms of handling this? I think the best thing you can do is ask your patients to bring in their cuffs and ask them what type of cuff they’re using. It really should be an upper arm cuff across the board, unless somebody’s had a bilateral mastectomy and lymphadenectomy, so they end up having pain if you use an upper arm cuff, or if they’re very, very obese and the cuffs really just won’t fit them. Those individuals can use wrist devices, but everyone else should use upper arm devices, because the wrist devices are pretty unreliable for the most part. Upper arm devices are much more likely to be reliable.

So I tell every patient to bring it into the office. It takes two minutes for a nurse or a medical assistant to double-check it against a better-quality office device, assuming that you have one in the office that’s validated. If you’re getting within a few millimeters of mercury of that device, I usually say about four to six millimeters of mercury, then you know that you’re getting something that, at least for that patient, seems to be valid, and that most likely has been validated, but they just haven’t published their validation.

Kevin Pho: You mentioned earlier that one of the trends is cuffless blood pressure devices. So talk more about those.

Jordana Cohen: Yeah, cuffless blood pressure devices. Most of them use technology that involves photoplethysmography, which is a similar technology to what’s used in pulse ox. They have a few different tricks that they’re using, mostly with either artificial intelligence or really fancy machine learning tools, to try to estimate, instead of using pressure, what your blood pressure is, based on the way these different pulsations travel through your blood vessels. So it’s an entirely different idea than blood pressure, almost, and it worries me quite a bit.

Most of the devices require that you use a validated blood pressure cuff to check a blood pressure and then calibrate them, but the calibration can drift very quickly in some of them. And they’re all claiming that they are these amazing blood pressure devices, and they’re marketing themselves as the most accurate device you’ll ever see, and none of them have been adequately vetted yet. Literally, the guideline, the international standard on how to vet them, just came out, so they could not possibly have been appropriately vetted yet.

I worry most about it because of that pulse ox technology, given recent publications in JAMA and the New England Journal showing that pulse ox is quite racist, and that there can be a much, much higher risk of hypoxemia on arterial oxygen levels in people who have darker skin tones who still show a normal pulse ox. This is the same technology. Now, these companies are not adequately publishing whether they’re even looking across ranges of skin tone, and whether they’re adjusting or accounting for skin tone in any way in developing their algorithms. So I’m just very, very concerned about the possibility of them introducing some systemic racism. Hopefully that won’t be the case, but I think we should all be really cautious and should be holding these device companies to pretty high standards when they’re putting these new devices out that, again, haven’t been vetted yet, while they’re advertising them as the most amazing device ever.

Kevin Pho: So are they widely available now? And in general, what do these cost, versus, say, a validated traditional blood pressure cuff?

Jordana Cohen: Several are available now. Several are FDA-cleared, even though, again, there’s no formal assessment protocol for these devices available yet, or it just came out in the last few weeks. In terms of the price, I believe they’re all quite a lot more expensive than what a typical blood pressure cuff would be.

Then there are several others being marketed that are not FDA-cleared and that aren’t even checking a blood pressure. They are really just random number generators, and those have been around for quite a while. If you look on Amazon or other online retailers, there are quite a few of these that claim they’re checking your blood pressure, and they most definitely are not.

Kevin Pho: So other than going to the VDL list and making sure that their cuff is validated, what other red flags should patients watch out for when considering a blood pressure cuff?

Jordana Cohen: I mentioned wrist devices, which I tend to avoid unless you have a real reason to need one. Another red flag you should look out for when purchasing one is if you’re purchasing it from a nontypical retailer. I’d say go to your pharmacy. Most pharmacies have several validated devices available off the shelf. If you’re going to purchase it online, you really need to do your research. I think that if you’re purchasing it from a pharmacy, it’s not a guarantee that it’s a great one, but it’s still at least more likely to be one that’s been validated.

Kevin Pho: We’re talking to Jordy Cohen. She’s an internal medicine physician and nephrologist. Her KevinMD article is titled “How the U.S. blood pressure validated device listing (VDL) ensures accurate readings and revolutionizes hypertension control.” Jordy, tell us some of the take-home messages you want to leave with the KevinMD audience.

Jordana Cohen: The key messages are that blood pressure accuracy really matters. We have narrower and narrower blood pressure goals as time goes on, and if we’re not checking an accurate blood pressure, we could be causing patients to have quite a bit of negative effects from medications that they don’t need to be having. We can both overtreat and undertreat. So it’s really important for us to be thinking about how accurate the blood pressure devices we’re using are, and to be making sure folks are checking blood pressures correctly with accurate devices. We have tools available for us to do it. Upper arm devices that have been validated, listed on our website, www.validatebp.org, can really provide us with more reliable information.

Kevin Pho: Jordy, thank you so much for sharing your time and insight, and thanks again for being on the show.

Jordana Cohen: Thanks for having me.