The Fitbit Irregular Rhythm Notifications is a software-only mobile medical application that is intended to be used with compatible consumer wrist-worn products to analyze pulse rate data to identify episodes of irregular heart rhythms suggestive of atrial fibrillation (AFib) and provide a notification to the user.

The Fitbit Irregular Rhythm Notifications is intended for over-the-counter (OTC) use. It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present; rather the Fitbit Irregular Rhythm Notifications is intended to opportunistically surface a notification of possible AFib when sufficient data are available for analysis.

These data are only captured when the user's still. Along with the user's risk factors, the Fitbit irreqular Rhythm Notifications can be used to supplement the decision for AFib screening. The Fitbit Irregular Rhythm Notfications is not intended to replace traditional methods of diagnosis or treatment.

The Fitbit Irregular Rhythm Notifications has not been tested for use in people under 22 years of age. It is also not intended for use in individuals previously diagnosed with AFib.

Device Description

The Fitbit Irreqular Rhythm Notifications consists of an algorithm that classifies pulse rate data, and a mobile application run within the Fitbit app that serves as the user interface (UI) and device display.

The Fitbit Irregular Rhythm Notifications leverages pulse rate data collected from compatible commercially available, general purpose wrist-worn products (e.g., smartwatch or fithess tracker). Photoplethysmograph (PPG) sensors consist of light-emitting diodes (LED) and photodiodes that detect changes in blood flow of a user's vasculature at any given moment. When the heart beats, it sends a pressure wave through the vasculature causing a blood flow increase. By monitoring the fluctuations the consumer wrist-worn products can measure pulse rate data. When the user is still the sensor detects when individual pulses reach the periphery (i.e., wrist) and measures beat-to-beat intervals.

If the analyzed data are consistent with signs of atrial fibrillation, a notification indicating that a heart rhythm showing signs suggestive of AFib will be displayed to the user. The Fitbit Irregular Rhythm Notifications will only surface a notification of a heart rhythm showing signs of AFib once in a 24-hour period.

The Fitbit Irregular Rhythm Notifications mobile app functions within the Fitbit consumer application and is run on a compatible, user-provided general purpose mobile computing product (e.g., smartphone or tablet). The Fitbit Irregular Rhythm Notifications mobile app serves as the display/user interface for the Fitbit Irregular Rhythm Notifications.

AI/ML Overview

Acceptance Criteria and Device Performance for Fitbit Irregular Rhythm Notifications

1. Table of Acceptance Criteria and Reported Device Performance

The provided document focuses on the substantial equivalence to a predicate device rather than explicitly stating acceptance criteria as a numerical target. However, it details the performance metrics demonstrated by the clinical study to support this equivalence. The key performance metric reported is the Positive Predictive Value (PPV) for AFib detection.

Acceptance Criteria (Implied)	Reported Device Performance
Clinical performance supportive of substantial equivalence to predicate device.	Positive Predictive Value (PPV) of 98.2% (97.5% LCB: 96.4%) in subjects with a positive algorithm detection.

2. Sample Size and Data Provenance

Test Set Sample Size: 225 subjects received a positive algorithm detection and wore an ECG patch for comparison.
Data Provenance: The study recruited subjects from Fitbit's U.S. user population. The data is prospective, as users consented and were instructed to perform specific actions (schedule a telehealth visit, wear an ECG patch) following algorithm detection.

3. Number of Experts and Qualifications for Ground Truth

The document states that "Data gathered from the ECG patch was analyzed by medical professionals to determine whether signs of AFib were present." It does not specify the exact number of experts or their detailed qualifications (e.g., "radiologist with 10 years of experience").

4. Adjudication Method for the Test Set

The document does not explicitly describe an adjudication method like 2+1 or 3+1. It states that "data gathered from the ECG patch was analyzed by medical professionals to determine whether signs of AFib were present," implying a single assessment or a consensus process not detailed.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned. The study focused on the standalone algorithm's performance against ECG ground truth, not on how human readers improve with or without AI assistance.

6. Standalone (Algorithm Only) Performance

Yes, a standalone performance study was conducted. The clinical study evaluated the Fitbit Irregular Rhythm Notifications algorithm's ability to identify irregular heart rhythms suggestive of AFib. The reported PPV of 98.2% is a measure of this standalone algorithmic performance.

7. Type of Ground Truth Used

The ground truth used for the test set was ECG patch data analyzed by medical professionals. This is a direct measure of cardiac electrical activity, considered a gold standard for AFib diagnosis.

8. Sample Size for the Training Set

The document does not specify the sample size for the training set. It mentions that the clinical study "recruited subjects from Fitbit's U.S. user population, inviting them to participate in a study. Upon consent, users had their PPG data analyzed for signs consistent with AFib by the algorithm." This describes part of the clinical validation, but not the training process or the data used for it.

9. How Ground Truth for the Training Set Was Established

The document does not provide details on how the ground truth for the training set was established. It only describes the ground truth establishment for the clinical validation test set (ECG patch data analyzed by medical professionals).

Summary

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April 8, 2022

Fitbit Inc Randy Parry Senior Regulatory Affairs Specialist 199 Fremont Street 14th Floor San Francisco, California 94105

Re: K212372

Trade/Device Name: Fitbit Irregular Rhythm Notifications Regulation Number: 21 CFR 870.2790 Regulation Name: Photoplethysmograph Analysis Software For Over-The-Counter Use Regulatory Class: Class II Product Code: QDB Dated: March 8, 2022 Received: March 9, 2022

Dear Randy Parry:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's

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requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Jennifer Shih Kozen Assistant Director Division of Cardiac Electrophysiology, Diagnostics and Monitoring Devices Office of Cardiovascular Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Indications for Use

510(k) Number (if known) K212372

Device Name

Fitbit Irreqular Rhythm Notifications

Indications for Use (Describe)

The Fitbit Irregular Rhythm Notifications is a software-only mobile medical application that is intended to be used with compatible consumer wrist-worn products to analyze pulse rate data to identify episodes of irregular heart rhythms suggestive of atrial fibillation (AFib) and provide a notification to the user.

The Fitbit Irregular Rhythm Notifications has not been tested for use in people under 22 years of age. It is also not intended for use in individuals previously diagnosed with AFib.

Type of Use (Select one or both, as applicable)

□ Prescription Use (Part 21 CFR 801 Subpart D)

X Over-The-Counter Use (21 CFR 801 Subpart C)

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Image /page/3/Picture/0 description: The image shows the Fitbit logo. The logo consists of a stylized turquoise-colored icon made up of small circles arranged in a pattern resembling a stylized person, followed by the word "fitbit" in a dark blue sans-serif font. The icon is positioned to the left of the word "fitbit".

510(K) Summary VII.

1. Submitter Information: Fitbit LLC 199 Fremont Street, 14th Floor

San Francisco, CA 94105

Contact Person: Randy Parry Phone: (415) 985-4778 Email: parran@google.com Date Prepared: March 8, 2022

2. Subject Device Information

Name of Device: Fitbit Irregular Rhythm Notifications Common or Usual Name: Irregular Rhythm Analysis Software Classification Name: Photoplethysmograph Analysis Software For Over-The-Counter Use Regulatory Class: Class II Product Code: QDB - 21 CFR 870.2790

1. Predicate Device Apple Inc., Irregular Rhythm Notification Feature (DEN180042)

4. Indications for Use

The Fitbit Irreqular Rhythm Notifications is intended for over-the-counter (OTC) use. It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present; rather the Fitbit Irregular Rhythm Notifications is intended to opportunistically surface a notification of possible AFib 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 Fitbit Irreqular Rhythm Notifications can be used to supplement the decision for AFib screening. The Fitbit Irreqular Rhythm Notifications is not intended to replace traditional methods of diagnosis or treatment.

The Fitbit Irregular Rhythm Notifications 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 diaqnosed with AFib.

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Image /page/4/Picture/0 description: The image shows the Fitbit logo. The logo consists of a stylized, teal-colored geometric shape to the left of the word "fitbit" in a dark teal sans-serif font. The geometric shape is made up of several small circles arranged in a grid-like pattern.

5. Device Description

Intended Use

The Fitbit Irregular Rhythm Notifications feature is a medical device (SaMD). The Fitbit Irregular Rhythm Notifications feature analyzes pulse rate data to identify heart rhythms that are consistent with atrial fibrillation (AFib) and if identified, provide a notification to the user.

Technological Characteristics

Table 7.1 Summary of Technological Characteristics and Substantial Equivalence
	Subject DeviceFitbit Irregular Rhythm Notifications	Predicate DeviceApple - Irregular Rhythm Notification
Intended Use	Analyze pulse rate gathered fromPPG pulse rate data to identifyepisodes of irregular heart rhythmssuggestive of atrial fibrillation (AFib)and provide a notification to the user.	Analyze pulse rate gathered fromPPG pulse rate data to identifyepisodes of irregular heart rhythmssuggestive of atrial fibrillation (AFib)and provide a notification to the user.
Indications for Use	The Fitbit Irregular Rhythm Notificationsis a software-only mobile medicalapplication that is intended to be usedwith compatible consumer wrist-wornproducts to analyze pulse rate data toidentify episodes of irregular heartrhythms suggestive of atrial fibrillation(AFib) and provide a notification to theuser.The Fitbit Irregular Rhythm Notificationsis intended for over-the-counter (OTC)use. It is not intended to provide anotification on every episode of irregularrhythm suggestive of AFib and theabsence of a notification is not intendedto indicate no disease process ispresent; rather the Fitbit IrregularRhythm Notifications is intended toopportunistically surface a notification ofpossible AFib when sufficient data areavailable for analysis.These data are only captured when theuser is still. Along with the user's riskfactors, the Fitbit Irregular RhythmNotifications can be used to supplementthe decision for AFib screening. TheFitbit Irregular Rhythm Notifications isnot intended to replace traditionalmethods of diagnosis or treatment.The Fitbit Irregular Rhythm Notificationshas not been tested for and is notintended for use in people under 22years of age. It is also not intended foruse in individuals previously diagnosedwith AFib.	The Irregular Rhythm NotificationFeature is a software-only mobilemedical application that is intended tobe used with the Apple Watch. Thefeature analyzes pulse rate data toidentify episodes of irregular heartrhythms suggestive of atrial fibrillation(AFib) and provides a notification to theuser.The feature is intended forover-the-counter (OTC) use. It is notintended to provide a notification onevery episode of irregular rhythmsuggestive of AFib and the absence of anotification is not intended to indicate nodisease process is present; rather thefeature is intended to opportunisticallysurface a notification of possible AFibwhen sufficient data are available foranalysis.These data are only captured when theuser is still. Along with the user's riskfactors, the feature can be used tosupplement the decision for AFibscreening. The feature is not intended toreplace traditional methods of diagnosisor treatment.The feature has not been tested for andis not intended for use in people under22 years of age. It is also not intendedfor use in individuals previouslydiagnosed with AFib.
Mechanism ofOperation	Software-only mobile medical applicationthat uses inputs from compatibleconsumer wrist-worn PPG sensors toanalyze pulse rate data to identifyepisodes of irregular heart rhythmssuggestive of AFib.	Software-only mobile medicalapplication that uses inputs fromwrist-worn Apple Watch PPG sensors toanalyze pulse rate data to identifyepisodes of irregular heart rhythmssuggestive of AFib.
DeviceClassification	Class II	Class II

FDA Product Codeand RegulatoryClassification	QDB - 870.2790	QDB - 870.2790
	Photoplethysmograph analysis softwarefor over-the-counter use	Photoplethysmograph analysis softwarefor over-the-counter use
Anatomical Site	Wrist-worn compatible consumerproduct with PPG sensors.	Wrist-worn Apple Watch with PPGSensors
Patient Population	Individuals (22 years or older)	Individuals (22 years or older)
Data storage	Pulse rate data stored locally onwrist-worn product until transmission to aserver.	Pulse rate data stored locally onwrist-worn product until transmission toa server.
Prescription/OTC	OTC	OTC
User interface	Mobile application run within the Fitbitconsumer app.	Mobile application run within the iPhoneApple Health App.
Use Method	Collects and analyzes tachogramsduring periods of stillness or sleep usinginput from PPG sensors.	Collects and analyzes a one-minutetachogram approximately every 4 hoursusing input from PPG sensors.
Limiting Factors	Motion, hand and finger movements,dark tattoos on the wrist, inadequateblood flow.Does not continuously monitor for signsof AFib.A lack of notification does not indicate anabsence of AFib.	Motion, hand and finger movements,dark tattoos on the wrist, inadequateblood flow.Does not continuously monitor for signsof AFib.A lack of notification does not indicatean absence of AFib.
Results ofalgorithm	Tachograms are classified as havingsigns of AFib, no signs of AFib orunanalyzable.	Tachograms are classified as eitherirregular rhythm or not AFib.Notification of a heart rate that showssigns consistent with atrial fibrillation.
History of events	History of events consistent with AFibviewable in the mobile application.	History of events consistent with AFibviewable in the mobile application.
Compatibledevices	Consumer wrist-worn products with PPGsensors (e.g., smartwatch or fitnesstracker) that have been qualified for usewith Fitbit Irregular Heart RhythmNotificationsFitbit SenseFitbit VersaFitbit Versa LiteFitbit Inspire 2	Apple Watch with PPG sensors (series 1and later).
Fitbit Charge 4

Summary of Technological Characteristics and Substantial Equivalence

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Image /page/5/Picture/0 description: The image shows the Fitbit logo. The logo consists of a teal-colored icon made up of several circles arranged in a diamond shape, followed by the word "fitbit" in a sans-serif font, also in teal. The logo is simple and modern, reflecting the company's focus on health and fitness tracking.

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Image /page/6/Picture/0 description: The image shows the Fitbit logo. The logo consists of a stylized turquoise icon made up of several circles arranged in a geometric pattern, followed by the word "fitbit" in a dark blue sans-serif font. The icon is positioned to the left of the word "fitbit".

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6. Performance Data

Testing verifying the performance requirements of the subject device was conducted and is included in this premarket notification, the results of which support substantial equivalence. A summary of the testing is included below:

Bench Testing/Non-Clinical Testing

The Fitbit Irreqular Rhythm Notifications utilizes signals derived from compatible consumer grade wrist-worn products. The wrist-worn products are qualified for use with the software to ensure that the data provided meet signal attribute and quality requirements necessary for heart rhythm analysis and to detect adequate PPG signal quality. Bench testing includes: product signal acquisition testing, aggressor testing for known challenge conditions potentially impacting the quality of PPG signal acquisition, and accuracy assessment of the inputs to the Fitbit Irregular Rhythm Notifications that are derived from the wrist-worn products. Qualification testing is repeated for all qualified wrist-wearable products. The algorithm is tested to ensure that it accepts and rejects data correctly and that it correctly analyzes the input data.

Software Testing Summary

The Fitbit Irregular Rhythm Notifications presents a "moderate" level of concern (LOC) as defined in FDA's Guidance for the Content of Premarket Submissions for Software Contained in Medical Devices (May 11, 2005) (Guidance Document). The software components consist of the Irregular Rhythm Notifications algorithm, which resides/runs on Fitbit servers, and the mobile app used for on-boarding, education and display of notification results. Testing supports that the algorithm analyzes pulse rate data and classifies it as having signs of AFib, having no signs of AFib, or unanalyzable. Testing of the mobile application demonstrates that the Fitbit Irregular Rhythm Notifications mobile application adequately surfaces on-boarding/educational information, generates user notifications when the feature identifies an irregular rhythm suggestive of AFib, and facilitates viewing of that notification.

Human Factors Testing Summary

A human factors study was designed to evaluate the critical and noncritical tasks associated with the use of the device.

Human Factors Usability testing was performed using a simulated version of the Fitbit Irregular Rhythm Notifications mobile app, representative of the final app. There were a total of 30 subjects distributed into two (2) user groups:

15 active interest participants adult laypeople (22 years and older) with active . interest in AFib, defined as individuals who:
- o Have concern regarding AFib and have an active interest in monitoring potential AFib, and

Confidential

K212372 Page 5 of 7

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Image /page/8/Picture/0 description: The image shows the Fitbit logo. The logo consists of a stylized, teal-colored icon to the left of the word "fitbit" in a sans-serif font, also in teal. The icon is made up of a grid of small circles arranged in a diamond shape.

Would use the app due to high interest o
15 passive interest participants adult laypeople (22 years and older) with passive ● interest in AFib, defined as individuals who:
- Do not have concern regarding AFib and do not have an active interest in O monitoring potential AFib. and
- Might use the app due to casual or passing interest. o

The Human Factors Validation demonstrated that the Fitbit Irregular Rhythm Notifications meets the special control requirements for human factors and usability testing that demonstrates the following:

a. The user can correctly use the device based solely on reading the device labeling.

b. The user can correctly interpret the device output and understand when to seek medical care.

Testing was also performed to assess consumers' ability to correctly self-select if the Irregular Rhythm Notifications app is intended for them. This testing involved 33 subjects, including both users for whom the app is intended, as well as persons outside the app's intended use population. The testing concluded that users can adequately self-select if the device is intended for them.

Clinical Testing Summary

A clinical study was conducted on the Fitbit Irreqular Rhythm Notifications algorithm. This study recruited subjects from Fitbit's U.S. user population, inviting them to participate in a study. Upon consent, users had their PPG data analyzed for signs consistent with AFib by the algorithm. The users whose data showed signs of AFib were then instructed to schedule a telehealth visit with a clinician. Subjects still meeting the inclusion criteria were then provided with an ECG patch and directed to simultaneously wear both the ECG patch and their Fitbit wrist-wearable, PPG-equipped product for seven (7) consecutive days and nights. Data gathered from the ECG patch was analyzed by medical professionals to determine whether signs of AFib were present and was compared to the corresponding Fitbit algorithm output.

In the 225 subjects who received a positive algorithm detection while wearing the ECG patch, the algorithm's positive predictive value (PPV) was 98.2% (97.5% LCB: 96.4%) and supports that the subject Fitbit Irreqular Rhythm Notifications is substantially equivalent to the predicate, Apple Inc. Irregular Rhythm Notification. A total of 2,094 adverse events were reported for 1,275 subjects. No adverse events reported were related to the Fitbit Irregular Rhythm Notifications software. Most adverse events were identified as possible risks in the study protocol, namely skin irritation from wearing a Fitbit or ECG patch, stress or anxiety from participating in the study, new information or diagnosis as the result of being in the study and combinations of multiple events.

7. Conclusion

The Fitbit Irregular Heart Rhythm Notifications is as safe and effective as the Apple -Irregular Rhythm Notification. Additionally, minor technological differences between the Fitbit

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feature and its predicate do not raise different questions of safety or effectiveness compared to the predicate. The Fitbit Irregular Heart Rhythm Notifications has the same intended use, indications for use, underlying technological characteristics, and similar principles of operation as the predicate device. Based on the similarities and performance testing, the subject device, Fitbit Irregular Rhythm Notifications, is substantially equivalent to the predicate device.

Regulation Number and Section

§ 870.2790 Photoplethysmograph analysis software for over-the-counter use.

(a)
Identification. A photoplethysmograph analysis software device for over-the-counter use analyzes photoplethysmograph data and provides information for identifying irregular heart rhythms. This device is not intended to provide a diagnosis.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Clinical performance testing must demonstrate the performance characteristics of the detection algorithm under anticipated conditions of use.
(2) Software verification, validation, and hazard analysis must be performed. Documentation must include a characterization of the technical specifications of the software, including the detection algorithm and its inputs and outputs.
(3) Non-clinical performance testing must demonstrate the ability of the device to detect adequate photoplethysmograph signal quality.
(4) Human factors and usability testing must demonstrate the following:
(i) The user can correctly use the device based solely on reading the device labeling; and
(ii) The user can correctly interpret the device output and understand when to seek medical care.
(5) Labeling must include:
(i) Hardware platform and operating system requirements;
(ii) Situations in which the device may not operate at an expected performance level;
(iii) A summary of the clinical performance testing conducted with the device;
(iv) A description of what the device measures and outputs to the user; and
(v) Guidance on interpretation of any results.