(84 days)
The Withings WBS01 Smart Body Scale is a body analyzer that measures weight and uses bioelectrical impedance analysis (BIA) technology to estimate body fat mass in generally healthy adults 18 years of age or older. It is intended for use in the home/domestic setting only.
WBS01 Smart Body Scale uses the BIA (Bioelectrical Impedance Analysis) technique. This method measures body composition by sending a low, safe electrical current through the body. The current passes freely through the fluids contained in muscle tissue, but encounters difficulty/resistance when it passes through fat tissue. This resistance of the fat tissue to the current is termed 'bioelectrical impedance', and is accurately measured by WBS01 Smart Body Scale.
WBS01 Smart Body Scale embeds a 802.11 (Wi-Fi) module that allows it to connect to the Internet. This module is a product add-on that is entirely independent from the body analyzer function, which does not rely on the wireless connection to carry out a bioelectrical impedance analysis and display its results. The scale uses this connectivity to offer users a complementary web and mobile interface to the scale's display, although users are instructed in the provided user manual that the only reference values are the measures displayed on the scale's display. By design. the body analysis and Wi-Fi functions never are enabled at the same time. The scale only connects to the Internet while no weight or bioelectrical impedance measures are being performed, and if a person steps on the scale while the Wi-Fi module is active, Wi-Fi immediately gets turned off therefore allowing the display and body analysis function to be enabled. The users profile details are stored locally in the scale so that they are immediately available when a bioelectrical impedance analysis needs to be performed. The scale without its Wi-Fi module is therefore an autonomous body fat analyzer, Wi-Fi functionality being a product add-on not being part of the body analyzer function and not affecting the safety and effectiveness of the body analyzer function in any way.
The provided text describes a 510(k) summary for the Withings WBS01 Smart Body Scale, which is a body analyzer that uses bioelectrical impedance analysis (BIA) to estimate body fat mass. The submission aims to demonstrate substantial equivalence to a predicate device, the TRANSTEK Glass Body Analyzer (Model: GBF-830).
However, the document does not contain a detailed study proving the device meets specific acceptance criteria with reported device performance values. It primarily focuses on comparing the proposed device to the predicate device and asserting substantial equivalence based on similar technology and intended use, with the main difference being the addition of Wi-Fi connectivity, which is described as not impacting the safety or effectiveness of the body analyzer function.
Therefore, many of the requested details about acceptance criteria, specific performance results, sample sizes, expert ground truth, and comprehensive study designs are not present in the provided text.
Here's a breakdown of what can and cannot be answered based on the provided document:
Acceptance Criteria and Study Information for Withings WBS01 Smart Body Scale
1. Table of Acceptance Criteria and Reported Device Performance
| Feature/Metric | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Body Fat Mass Estimation | Not explicitly stated in terms of specific thresholds (e.g., accuracy, precision, bias compared to a gold standard). | Not reported in the document. The submission implies that since it uses the same BIA technology as the predicate, its performance is considered equivalent. |
| Weight Measurement | Not explicitly stated in terms of specific thresholds (e.g., accuracy, precision). | Not reported in the document. |
| Wireless Connectivity (Wi-Fi) | User electrical safety and acceptable wireless radiation emission in use environment. | Bench tests performed to ensure these. FCC ID certification cited as basis for low risk of thermal injury or interference. (No specific numerical criteria or performance values are given, only a qualitative statement of compliance). |
| Substantial Equivalence to Predicate | Similar indication for use, same BIA technology, and technological difference (Wi-Fi) that does not impact safety or effectiveness. | Stated as concluded by the submitter and accepted by the FDA (as per the 510(k) clearance letter). |
2. Sample size used for the test set and the data provenance
- Sample Size for Test Set: Not specified. The document does not describe a clinical performance study using a "test set" in the traditional sense for evaluating body fat accuracy.
- Data Provenance: Not applicable, as a test set study with performance data is not described.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Not applicable. No direct clinical performance study where expert ground truth was established for a test set is described in this 510(k) summary.
4. Adjudication method for the test set
- Not applicable. No test set requiring adjudication is described.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, and the effect size of how much human readers improve with AI vs without AI assistance
- Not applicable. This device is a standalone body composition analyzer, not an AI-assisted diagnostic tool that would involve human readers or MRMC studies.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done
- The device itself is a standalone algorithm/device for measuring body composition. However, the document does not describe a specific standalone performance study to quantify its accuracy against a gold standard (e.g., DEXA or underwater weighing). Instead, it relies on substantial equivalence to a predicate device. The "display results" are what the user sees, and these are presented as the "only reference values."
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Not explicitly stated for the proposed device's performance. For BIA devices, ground truth for body fat estimation typically involves methods like DEXA, underwater weighing, or MRI. The document does not mention the use of such a ground truth for testing the WBS01. It relies on the predicate device's established performance using BIA.
8. The sample size for the training set
- Not applicable. This document describes a medical device, not a machine learning model that would require a "training set" in the context of deep learning or advanced AI. The BIA technology itself is a well-established method using physics principles and calibrated algorithms, not a dynamically trained AI system.
9. How the ground truth for the training set was established
- Not applicable, as there is no "training set" in the context of a machine learning algorithm being developed or presented in this submission. The BIA technology uses physical measurements and equations.
§ 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.