Article: Establishing Trust in Wearable Medical Devices

Many of the topics covered in this article I have covered in this blog. Most recently, my discussion of signal detection and the Apple Watch (https://medicalremoteprogramming.blogspot.com/2019/12/signal-detection-and-apple-watch.html) that I suggest that you read after reading this article from Machine Design.

Here's the link to the article: https://www.machinedesign.com/medical-design/article/21122718/establishing-trust-in-healthcare-wearables?utm_source=MN+MD+Medical+Design&utm_medium=email&utm_campaign=CPS200206038&o_eid=7596G0176945B2B&rdx.ident%5Bpull%5D=omeda%7C7596G0176945B2B&oly_enc_id=7596G0176945B2B

Here are a few quotes from the article.

To say that we can get personal health insight from continuous monitoring presumes a “chain of trust.” In other words: 

• The interpretation of any data must not only be accurate but reliable. The challenge lies in handling “borderline” data. Any interpreting strategy or algorithm faces data sets that it finds ambiguous. For an algorithm to be reliable, users must be able to quantitatively understand its detection limits and error characteristics.

• The data and/or its interpretation must reliably reach the decision-maker for it to become actionable.

• The data must be correctly associated with historical records of the patient for it to have context.

• The data must be proven to be authentic to trigger any meaningful action.

However, using clinical equipment to capture vital signs that are representative of the wearable use cases is often difficult and sometimes inaccurate. To avoid a rash of false positives or false negatives, one must carefully select the population of test subjects and carefully develop the representative use cases. It’s also important to compare data from the patient’s own history or baseline, keeping in mind that this baseline isn’t static as the patient ages and undergoes other changes.

Follow-up: Apple Watch 5, Afib detection, NY Times Article

The New York Times has published an article regarding the Apple Watch 5's capability to detect atrial fibrillation. The link to the article is below:

https://www.nytimes.com/2019/12/26/upshot/apple-watch-atrial-fibrillation.html?te=1&nl=personal-tech&emc=edit_ct_20191226?campaign_id=38&instance_id=14801&segment_id=19884&user_id=d7e858ffd01b131c28733046812ca088&regi_id=6759438320191226

The title and the subtitle of the article provide a good summary of what the author (Aaron E. Carroll) found:

"The Watch Is Smart, but It Can’t Replace Your Doctor
Apple has been advertising its watch’s ability to detect atrial fibrillation. The reality doesn’t quite live up to the promise."

With reference to my article, the Times article provides more detail on the trial that Apple ran to test the effectiveness of the Apple Watch's ability to detect atrial fibrillation. That provide interesting and enlightening, and clarified some of the issues I found with how the study was reported for both the procedure and the results. In addition, the author and I concur regarding the Apple Watch's extremely high reported rate of false positives for atrial fibrillation. I find this quite interesting when you consider that screening for atrial fibrillation can be as simple as taking the patient's pulse. 

Here are a few quotes from the article:

"Of the 450 participants [these are study participants where the Apple Watch had detected atrial fibrillation] who returned patches , atrial fibrillation was confirmed in 34 percent, or 153 people. 
...

Many news outlets reporting on the study mentioned a topline result: a “positive predictive value” of 84 percent. That statistic refers to the chance that someone actually has the condition if he or she gets a positive test result.

But this result wasn’t calculated from any of the numbers above. It specifically refers to the subset of patients who had an irregular pulse notification while wearing their confirmatory patch. That’s a very small minority of participants. Of the 86 who got a notification while wearing a patch, 72 had confirmed evidence of atrial fibrillation. (Dividing 72 by 86 yields 0.84, which is how you get a positive predictive value of 84 percent.)

Positive predictive values, although useful when talking to patients, are not always a good measure of a test’s effectiveness. When you test a device on a group where everyone has a disease, for instance, all positive results are correct."
...

There are positive messages from this study. There’s potential to use commercial devices to monitor and assess people outside of the clinical setting, and there’s clearly an appetite for it as well. But for now and based on these results, while there may be reasons to own an Apple Watch, using it as a widespread screen for atrial fibrillation probably isn’t one."

New Wearable Sensor Detects Gout and Other Medical Conditions

I just came across this article regarding a wearable sensor systems and thought that I would share it. This could be a component in a remote monitoring system. The sensor's information source is the person's sweat. "Sensor can pick up small concentrations of metabolites in sweat and provide readings over long periods of time." To turn this into a remote monitoring system, all that's required is a means to transmit the data over wireless. 

From the article:

The team’s goal is a sensor that lets doctors continuously monitor the condition of patients with illnesses such as cardiovascular disease, diabetes, and kidney disease, all of which put abnormal levels of nutrients or metabolites in the bloodstream. Patients would be better off if their physician knew more about their personal conditions and this method avoids tests that require needles and blood sampling.

“Such wearable sweat sensors could rapidly, continuously, and noninvasively capture changes in health at molecular levels,” Gao says. “They could make personalized monitoring, early diagnosis, and timely intervention possible.”

Here's the link to the article: https://www.machinedesign.com/mechanical-motion-systems/new-wearable-sensor-detects-gout-and-other-medical-conditions?NL=MD-005&sfvc4enews=42&cl=article_1_b&utm_rid=CPG05000003255032&utm_campaign=30434&utm_medium=email&elq2=23b7290219db4be5b4a569bc51f96d6e&oly_enc_id=7798C8395367J3R

Apple Watch 5: Heart Monitoring Capabilities -- Afib

The Apple Watch 5 has a heart rhythm monitoring capability that is tuned to detecting the presence of atrial fibrillation, AKA, Afib. Apple categorically states that the watch is unable to detect a heart attack. (And by implication, the likelihood of a heart attack occurring within minutes or hours.)

You have to manually enable your heart monitoring system (Watch and iPhone) to detect Afib. This not part of the default configuration. Here's the link for setting it up: https://support.apple.com/en-us/HT208931#afib

Here's what Apple says about the capabilities of their system and note that it requires both the Apple Watch 5 and an iPhone: 

INDICATIONS FOR USE (NON-EU REGIONS)

The Irregular Rhythm Notification Feature is a software-only mobile medical application that is intended to be used with the Apple Watch. The feature analyzes pulse rate data to identify episodes of irregular heart rhythms suggestive of atrial fibrillation (AF) and provides a notification to the user. The feature is intended for over-the-counter (OTC) use. It is not intended to provide a notification on every episode of irregular rhythm suggestive of AF and the absence of a notification is not intended to indicate no disease process is present; rather the feature is intended to opportunistically surface a notification of possible AF when sufficient data are available for analysis. These data are only captured when the user is still. Along with the user’s risk factors, the feature can be used to supplement the decision for AF screening. The feature is not intended to replace traditional methods of diagnosis or treatment.

The feature has not been tested for and is not intended for use in people under 22 years of age. It is also not intended for use in individuals previously diagnosed with AF.

INTENDED PURPOSE (EU REGION)

Intended Use

The Irregular Rhythm Notification Feature (IRNF) is intended to pre-screen and notify the user of the presence of irregular rhythms suggestive of atrial fibrillation (AF). The feature can be used to supplement a clinician’s decision to screen for possible AF. The feature is intended for over-the-counter (OTC) use.

The feature has not been tested for and is not intended for use in people under 22 years of age. It is also not intended for use in individuals previously diagnosed with AF.

Indications

The feature is indicated to pre-screen for irregular rhythms suggestive of AF for anyone aged 22 years and over.

USING THE IRREGULAR RHYTHM NOTIFICATION FEATURE Set-Up/On-boarding

• Open the Health app on your iPhone.
• Navigate to “Heart”, then select “Irregular Rhythm Notifications”.
• Follow the onscreen instructions.

Receiving a Notification

Once the feature is turned on, you will receive a notification if the feature identified a heart rhythm suggestive of AF and confirmed it on multiple readings.
If you have not been diagnosed with AF by a GP, you should discuss the notification with your doctor.

All data collected and analysed by the Irregular Rhythm Notification Feature is saved to the Health app on your iPhone. If you choose to, you can share that information by exporting your health data in the Health app.

SAFETY AND PERFORMANCE

In a study of 226 participants aged 22 years or older who had received an AF notification while wearing Apple Watch and subsequently wore an electrocardiogram (ECG) patch for approximately one week, 41.6% (94/226) had AF detected by ECG patch. During concurrent wear of Apple Watch and an ECG patch, 57/226 participants received an AF notification. Of those, 78.9% (45/57) showed concordant AF on the ECG patch and 98.2% (56/57) showed AF and other clinically relevant arrhythmias. A total of 370 irregular rhythm notifications with readable ECG patch data was received by the 57 participants. Of those 370 notifications, 322 (87.0%) were assessed to be AF, 47 (12.7%) were arrhythmias other than AF and 1 (0.3%) was sinus rhythm. These results demonstrate that, while in the majority of cases the notification will accurately represent the presence of AF, in some instances, a notification may indicate the presence of an arrhythmia other than AF. No serious device adverse effects were observed.

CAUTIONS

The Irregular Rhythm Notification Feature cannot detect heart attacks. If you ever experience chest pain, pressure, tightness or what you think is a heart attack, call emergency services.

The Irregular Rhythm Notification Feature is not constantly looking for AF and should not be relied on as a continuous monitor. This means the feature cannot detect all instances of AF and people with AF may not get a notification.

• Not intended for use by individuals previously diagnosed with AF.
• Notifications made by this feature are potential findings, not a complete diagnosis of cardiac conditions. All notifications should be reviewed by a medical professional for clinical decision making.
• Apple does not guarantee that you are not experiencing an arrhythmia or other health conditions even in the absence of an irregular rhythm notification. You should notify your GP if you experience any changes to your health.
• For best results, make sure your Apple Watch fits snugly on top of your wrist. The heart rate sensor should stay close to your skin.

From the information provided I am unable to determine how the Afib monitoring system detects Afib. It does seem use an additional capability beyond heart rate system, but from what little I can understand, it uses software running on either the watch and/or the iPhone and uses as input the data from the heart rate system.

I have no idea what algorithms the Apple heart monitoring system is using to detect atrial fibrillation (AF), but if you read the study above, you'll note that apparently, the Apple system has significant false positive rate. Walking through the study, to qualify as a subject for the study, you had to have had a positive indication of AF by the Apple system. That's the one clear message from the study. Another clear message is that both the Apple system and the AF patch can detect heart arrhythmia  other than AF, but what those were is unclear. Unfortunately the way the data is reported does not provide full clarity into the procedure and results. So there's not much more that I can comfortably conclude.

I feel comfortable stating that if you're wearing the Apple Watch and using the AF detection system and you get an AF indication, it's worth your time to get it checked out even knowing full well that the indication is more than likely to be a false positive.

However, high AF false positive rate of nearly 60% is concerning from the standpoint of those who have the Apple AF detection system activated and receive false positive indications. Information like this gets around and users may have tendency to ignore the AF indications when in fact they should be paying attention to them. To curb the possibility that someone ignores an accurately reported AF indication from the Apple system, it would behove Apple to include with the AF notification a check list displayed on the iPhone the walk the user through to determine if in fact this is an AF event.

Article: Year of Telehealth

Here's an article telling us what lots of us already have learned, that telehealth is an up a coming method of providing effective and cost-effective as well as continuous medical care where ever a patient may be. Here's the link to the article: https://www.beckershospitalreview.com/telehealth/dr-toby-cosgrove-2019-will-be-the-year-of-telehealth.html

Here's a quote from the article that I think is of interest:

"[Oakland, Calif.-based Kaiser Permanente] is seeing over 50 percent of their patients distantly," Dr. Cosgrove told CNBC.

What Cosgrove isn't telling us is how telehealth is being provided. Telehealth is pretty loosely defined. It can mean that patients have access to a health care provider through chat or the telephone. Or it can mean something more sophisticated such as continuous medical-device communication and automated monitoring. One way or another telehealth is clearly on the rise and will likely become the standard for providing care.

Apple Watch 4, Preview of Medical-Monitoring Features

Here's an article regarding the Apple Watch 4 and what are suppose to be built in medical monitoring features.

Here's the link: https://www.mobihealthnews.com/content/apple-watch-series-4-will-have-fda-cleared-ecg-fall-detection?mkt_tok=eyJpIjoiTkRVMk0yVmxNamsyWkRneiIsInQiOiJjWXRoaVpENmhJYlBRNFlzVVBYZ3hrc0VEVFdsYmNLUG1FQUIrQmcyMnVHMTRwSnBORDh6cW1Da1kzbjJqS2JxbHcydjRuTk0zaG5qRzBvMFR1MmdiMmZyNGhyXC9SZmYyYkduaSs5R0tyRG85TXkrMHVxTnFFYXFrVE5jWHpIRWwifQ%3D%3D

Here's the list of new medically-related features:

1. ECG (30 second rhythm "strip")
2. A-Fib detection (of course, if you're paying attention and you know the symptoms, you'll probably know sooner than the watch.)
3. Fall detection (as in when the person falls, the watch detects that it has occurred)

All information is sent back to Apple Health Records where all this information be accessible to a physician/cardiologist.

Apple has received FDA approval, according to the article. 

I'm not going to comment until I've had a little more time to study the Apple Watch 4 except to say, if you can detect A-Fib, then why not V-Fib? V-Fib is much more life threatening. Also too, if you've got a 30 second rhythm snap shot, you can do a lot with that. 

I'll touch on these and other questions regarding the Apple Watch 4 and Apple's effort to product a remote medical monitoring device and medical monitoring system later. 

Measuring cortisol — the stress hormone, remotely

Having the ability to remotely and continuously measure the level of a stress-related hormone would seem to be something of real value.

A new wearable biosensor, developed by the Salleo lab at Stanford, measures the amount of cortisol in a person’s sweat. 

Here is the link to the announcement/article: https://www.medicaldesignbriefs.com/component/content/article/mdb/insider/32762?utm_source=TBnewsletter&utm_medium=Email&utm_campaign=20180808_Medical_Newsletter&eid=376600177&bid=2199287

Article: Wearable Technology Is the Future of Healthcare

A bit of light reading about wearable fitness and medical devices.

Here's the link to the article: https://www.hcanews.com/news/wearable-technology-is-the-future-of-healthcare

An interesting quote from the article ...

There is no doubt that the adoption and retention of medical wearable devices will, at least for now and the foreseeable future, outrun that of general fitness wearable devices. This is understandable, as they fulfill a direct and current need for the consumer. However, my belief is, and I assume yours too, if you believe in prevention over treatment, that the more general one of these two has the feared but powerful potential to truly change the status quo. Where now, overall health goes down just before the age of 50, general fitness wearable devices could move up that number.  ...