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The KRELL Weight & Body Fat Monitoring Scale is indicated to measure body weight and impedance and estimate the percentage of Body Fat and body water, Bones mass using BIA (bioelectrical impedance analysis). This product is for use by generally healthy adults and children (from age 10 and up) who are not ill, feverish, have a chronic or acute disease, or a condition that affects the level of hydration such as pregnancy.

The patient steps on the scale device, where two electrodes are located. The patient must step on the electrodes with bare feet, with normal moisture. Through harmless current stimulation of 500 µA, at 50 kHz, the Krell Body Fat Analyzer calculates the body fat percentage. This calculation is done via the Bioelectrical Impedance Method. The current is passed through the body and the impedance of the body determines the body fat. The calculation is based upon electrical impedance, height, age. and gender. The calculation is performed via internal software, which uses the variables programmed in by the user. There are elements of this process that can produce erroneous readings, such as dry feet or improperprogrammed data. The User's Manual defines items which could cause erroneous readings.

Here's a breakdown of the acceptance criteria and study information based on the provided document:

Acceptance Criteria and Device Performance

The document states that "Clinical testing was used to validate the effectiveness and accuracy of the device. All test results were satisfactory." However, it does not provide specific numerical acceptance criteria for accuracy or effectiveness, nor does it present detailed performance metrics other than the general statement that results were "satisfactory."

Without explicit targets, it's impossible to create a table comparing acceptance criteria to reported device performance. The submission relies primarily on demonstrating substantial equivalence to predicate devices (Tanita BC-533, K040778; Bonso Health o meter BMF583, K030349) rather than establishing and meeting quantitative performance goals for a de novo device.

Study Details

Here's what can be extracted about the study from the provided 510(k) summary:

1. Sample size used for the test set and the data provenance:

   • Sample Size: Not specified in the document.
   • Data Provenance: Not explicitly stated (e.g., country of origin, retrospective/prospective). The device company is based in China, but the location of the clinical testing is not mentioned. It is implied to be prospective clinical testing to "validate the effectiveness and accuracy of the device."

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Not specified. The document only mentions that the Bioelectrical Impedance Method "has been validated via DXA (Dual Energy X-Ray Absorptiometry)," implying DXA was used as the ground truth. However, details on who performed or interpreted the DXA scans, or their qualifications, are not provided in the context of this specific device's validation study.

3. Adjudication method (e.g., 2+1, 3+1, none) for the test set:

   • Not specified.

4. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • Not applicable. This device is a standalone body fat and weight scale, not an AI-assisted diagnostic tool that would involve human readers or comparative effectiveness studies of this type.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Yes, a standalone study was done. The device operates as a standalone unit, calculating body fat percentage via its internal software using Bioelectrical Impedance through electrodes. The clinical testing mentioned in point 8 ("Clinical testing was used to validate the effectiveness and accuracy of the device") supports this standalone performance.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • The document states, "This bioelectrical impedance method has been validated via DXA (Dual Energy X-Ray Absorptiometry)." This indicates that DXA (Dual Energy X-Ray Absorptiometry) was used as the ground truth for validating the bioelectrical impedance method. DXA is a well-established method for measuring body composition, including body fat.

7. The sample size for the training set:

   • Not specified. While the device uses internal software, the document treats the Bioelectrical Impedance Method itself as having been previously validated, rather than detailing a specific training set for this device's algorithm.

8. How the ground truth for the training set was established:

   • Not specified. Assuming the "bioelectrical impedance method" was itself developed and validated, the ground truth would have been established through methods like DXA in those earlier validation efforts, but this document does not provide details specific to the training of this particular device's internal software.

Summary of Missing Information:

It's important to note that the provided 510(k) summary is quite brief on the details of the clinical validation study. Common information expected in such submissions, like specific sample sizes, demographic breakdowns of study participants, detailed performance metrics (e.g., mean absolute error, correlation coefficients, or agreement rates with DXA), and specific acceptance criteria, are not present. The submission relies more on the general statement of "satisfactory" test results and the established validity of the BIA method, along with substantial equivalence to predicate devices.

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