(90 days)
The Stayhealthy BC1 and the Stayhealthy/Fitness Expert BC2 devices are used solely to estimate the body fat and lean muscle components of the body using bioelectrical impedance technology.
The Stayhealthy Calorie tracker (CT1) and the Stayhealthy/Fitness Expert Calorie Tracker (CT2) are companion devices and are used solely to determine the calories used by a client when worn for a given period of time.
The BC1 and BC2 can output, via computer driven software the percent body fat of a person. The lean body mass can also be displayed. The devices are intended for use by both men and women who are 18 and older. The CT1 and the CT2 the companion devices can output, via computer driven software the number calories used by a person. The calories used can also be displayed. The BC1, BC2, CT1 and CT2 are not intended to be used to diagnose any known disease.
The Stayhealthy BC1 and Stayhealthy/ Fitness expert BC2, Body Composition Analyzer is a computer-operated and web enabled body composition analyzer that utilizes BIA (bioelectrical impedance analysis) to determine body fat percent and lean body mass percent. Both devices are about 10 inches across. The BC1 has an oval shape and is about 3 inches thick. The BC2 has an almost square shape with rounded corners. Both devices are made of slate grey plastics with polished metal inserts that are held by the hands to emit and receive signals to and from the body. The BC1 has an RS232 output socket and the BC2 has a USB output socket. Both devices have a dock where the calorie tracker is docked to upload its data. The CT1 and CT2 are both about 2 by 3 inches and made of slate gray plastics with a single display window and a docking port. They can be attached to clothes on the body via a clip on the back.
Here's an analysis based on the provided text, outlining the acceptance criteria and study details for the Stayhealthy BC1/BC2 Body Composition Analyzers:
The document does not explicitly state "acceptance criteria" in a quantitative, pre-defined manner. Instead, it describes a clinical trial proving the device's accuracy and then concludes that the device is "safe, effective and perform as good as or better than the predicate device." Therefore, the reported device performance is aligned with the outcome of this study, aiming for a tight correlation and no significant difference from the "gold standard."
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Tight correlation between BC1 and hydrostatic immersion methods. | Result: "The results showed a tight correlation between the two methods of measurement over the age range and the weight range used." |
| Minimal variation in repeated BC1 measurements. | Result: "There was less than a 0.5% variation in three BC1 measurements made on each individual." |
| No significant difference between BC1 and hydrostatic methods for total body composition values. | Result: "There was no significant difference between the total body composition values for the hydrostatic method compared to the BC1 (BIA method) (P value 0.05)." |
| Device performance is as good as or better than the predicate device (Omron Body Fat Analyzer Model HBF-306 K011652). | Conclusion: "both devices are safe, effective and perform as good as or better than the predicate device." |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: 72 subjects
- Data Provenance: The study was commissioned by Stayhealthy and performed by the University of East Tennessee. This suggests the data is likely from the United States.
- Retrospective or Prospective: Not explicitly stated, but clinical trials are typically prospective studies where data is collected for the purpose of the study.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Number of Experts: Not applicable in the traditional sense of expert review for medical imaging or diagnosis.
- Qualifications of Experts: The "gold standard" for body fat estimation used was hydrostatic immersion. This is a scientific measurement method, not typically performed by "experts" in the sense of physicians or radiologists making diagnoses. The specialists performing and interpreting hydrostatic immersion would be trained in this specific anthropometric technique. The document does not specify their roles or qualifications.
4. Adjudication Method for the Test Set
- Adjudication Method: Not applicable. The comparison was made between the device's measurements and the "gold standard" (hydrostatic immersion), which provides a direct quantitative measurement. There was no need for adjudication among multiple human reviewers for interpretation.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
- Was it done?: No, an MRMC comparative effectiveness study was not done. This study focuses on the accuracy of the device against a "gold standard" measurement, not on human reader performance with or without AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Was it done?: Yes, the described study is a standalone performance study of the Stayhealthy BC1 device. It compares the device's output (body fat percent via BIA) directly to a "gold standard" measurement (hydrostatic immersion), without human interpretation as part of the primary outcome assessment.
7. The Type of Ground Truth Used
- Ground Truth Type: A "gold standard" scientific measurement: Hydrostatic Immersion for estimation of body fat percent.
8. The Sample Size for the Training Set
- Sample Size: The document does not provide information about a specific training set size. The study described is a clinical validation study, likely for the already developed algorithm. The development and training of the BIA algorithm would have occurred prior to this validation study, and those details are not included in this summary.
9. How the Ground Truth for the Training Set Was Established
- How Established: The document does not provide information on how the ground truth for any potential training set was established. Given the nature of BIA devices, the training of the algorithm typically involves comparing BIA readings against known body composition measurements (like DEXA, hydrostatic weighing, or other validated methods) in a diverse population to establish the predictive model. However, these details are absent from the provided text.
§ 870.2770 Impedance plethysmograph.
(a)
Identification. An impedance plethysmograph is a device used to estimate peripheral blood flow by measuring electrical impedance changes in a region of the body such as the arms and legs.(b)
Classification. Class II (special controls). The device, when it is a body composition analyzer which is not intended to diagnose or treat any medical condition, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.