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The StimSox™ System is indicated to temporarily increase local blood circulation in healthy leg muscles and immediate post-surgical stimulation of calf muscles to prevent venous thrombosis.

The StimSox™ System is comprised of a battery powered electrical stimulator, disposable gel electrodes, two left foot boots, two right foot boots, and three AAA batteries.

The provided document is a 510(k) premarket notification for the StimSox™ System. It focuses on demonstrating substantial equivalence to predicate devices, rather than presenting a standalone clinical study with detailed acceptance criteria and performance data for a new device.

Therefore, the information requested regarding acceptance criteria, study design, sample sizes, expert ground truth, adjudication methods, MRMC studies, and ground truth establishment for training sets is largely Not Applicable or Not Provided in this type of submission.

Here's a breakdown based on the available information:

1. Table of Acceptance Criteria and Reported Device Performance

This document does not present a table of specific acceptance criteria in numerical terms (e.g., sensitivity, specificity, or improvement percentage) for a clinical outcome, nor does it explicitly report the StimSox™ System's performance against such criteria. The "performance data" mentioned focuses on safety, electrical standards, and biocompatibility, which are part of demonstrating substantial equivalence, not clinical effectiveness in the way a diagnostic AI might be evaluated.

The relevant section, "VIII. CLINICAL EVALUATION," discusses peer-reviewed journal articles for the predicate technology, not a direct study of the StimSox™ System itself. The overall conclusion states that these studies "demonstrated that stimulation on sole of the foot can lead to a temporary increase in local blood circulation in calf muscles. This increase in blood flow may help reduce the risk of venous thrombosis." This reflects the claimed benefit of the technology, broadly, rather than specific performance metrics for this device against pre-defined acceptance criteria.

2. Sample Sizes used for the test set and data provenance

• Sample Size for Test Set: Not applicable / Not provided. The submission refers to existing peer-reviewed articles on the technology itself, not a new clinical trial for the StimSox™ System with a "test set."
• Data Provenance: The document refers to peer-reviewed journal articles (Czyrny JJ, et al. 2010; Kaplan RE, et al. 2002). Specific details about the country of origin of the data or whether they were retrospective or prospective studies are not provided within this 510(k) summary.

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

Not applicable / Not provided. This type of detail would be found in a clinical study report for a new device, which is not what this 510(k) summary contains. The "ground truth" for the claims cited from the predicate literature would be the clinical outcomes and measurements reported in those studies, as interpreted by the authors and peer reviewers.

4. Adjudication method for the test set

Not applicable / Not provided. As there's no "test set" for a new clinical study of the StimSox™ System in this document, no adjudication method is described.

5. 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. The StimSox™ System is a powered muscle stimulator, not an AI-assisted diagnostic tool for "human readers." Therefore, an MRMC comparative effectiveness study is irrelevant to this device.

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

Not applicable. The StimSox™ System is a physical medical device, not a standalone algorithm. Its performance is evaluated through electrical safety, biocompatibility, and by referencing the clinical effectiveness of similar technology as demonstrated in published literature.

7. The type of ground truth used

The "ground truth" for the clinical claims (increased local blood circulation, prevention of venous thrombosis) is based on the findings of peer-reviewed scientific literature related to electrical foot stimulation. These studies would have used clinical measures and outcomes data to establish their findings. For example, Czyrny JJ, et al. concluded "electrical foot stimulation is at least as effective as knee-high intermittent pneumatic compression in increasing popliteal and femoral blood flow velocity," which implies measurements of blood flow velocity as the basis for their conclusions.

8. The sample size for the training set

Not applicable / Not provided. The StimSox™ System is not an AI/ML algorithm that requires a "training set" in the context of machine learning. The term "training set" is not relevant to its development as described here.

9. How the ground truth for the training set was established

Not applicable. See point 8.

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The StimSox™ System is indicated to temporarily increase local blood circulation in healthy leg muscles.

The StimSox™ System is comprised of a battery powered electrical stimulator, disposable gel electrodes, two left foot boots, two right foot boots, three AAA batteries and user manual. The StimSox™ Stimulator software is embedded firmware written for a microcontroller. The software in the StimSox™ Stimulator is for input controls and output display. There is no operating system. It is a real-time loop that is event driven based on the three buttons on the box.

The provided text describes a 510(k) premarket notification for the StimSox™ System, a powered muscle stimulator. The document focuses on demonstrating substantial equivalence to a predicate device, the AMD 6605 TENS/NMES Stimulator.

Here's an analysis of the acceptance criteria and supporting study information, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a table of "acceptance criteria" for the StimSox™ System in terms of performance metrics like sensitivity, specificity, or AUC, as might be found for a diagnostic AI device. Instead, it demonstrates "substantial equivalence" to a predicate device by comparing technological characteristics and showing compliance with relevant safety and performance standards. The "performance" is largely demonstrated through these comparisons and a validation study mentioned for current increments.

2. Sample Size Used for the Test Set and Data Provenance

The document mentions a "StimSox validation study" which "demonstrated that the 1.0mA increments were safe and effective in achieving the desired clinical response." However, it does not provide specific details on the sample size used for this test set, nor the data provenance (e.g., country of origin, retrospective/prospective nature).

It also references "one study (Thrombosis and Haemostasis. Kaplan RE et al., Throm Haemost 2002;88:2004)" for electrode placement differences, stating it found foot electrodes more comfortable and effective. This study was "not conducted with the predicate," and details about its sample size or provenance are not given in the context of the StimSox validation.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

This information is not provided in the document. The nature of the device (powered muscle stimulator) and its intended use (increasing local blood circulation) would likely involve physiological measurements rather than expert image interpretation for ground truth.

4. Adjudication Method for the Test Set

This information is not provided in the document. Given the nature of a muscle stimulator, the "ground truth" would likely be objective physiological measurements (e.g., blood flow, muscle contraction), rather than subjective expert assessment requiring adjudication.

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

An MRMC study is typically performed for diagnostic devices where human readers interpret medical images or data. For a powered muscle stimulator, an MRMC study comparing human reader improvement with and without AI assistance is not applicable and was not performed/reported.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

The StimSox™ System is a hardware device with embedded firmware for input controls and output display. It is not an AI algorithm that provides diagnostic or predictive outputs in a standalone manner. Therefore, a standalone performance study in the context of "algorithm only" is not applicable and was not performed/reported as it would be for an AI/ML-based diagnostic device. The device's "performance" is its ability to deliver electrical stimulation as intended for its physiological effect.

7. Type of Ground Truth Used

Based on the nature of the device and the brief mention of the validation study:

• The "desired clinical response" for the StimSox validation study (a "small contraction of the plantar muscles of the foot") suggests physiological measurements or direct observation of muscle response would constitute the ground truth.
• The indication ("temporarily increase local blood circulation") would imply ground truth established by physiological measurements of blood flow (e.g., Doppler ultrasound, plethysmography).

8. Sample Size for the Training Set

The StimSox™ System uses "embedded firmware written for a microcontroller" with a "real-time loop that is event driven." This indicates traditional microcontroller programming, not a machine learning model that requires a distinct "training set." Therefore, the concept of a "training set" sample size is not applicable to this device in the same way it would be for an AI/ML system.

9. How the Ground Truth for the Training Set Was Established

As there is no indication of a machine learning model or a "training set" in the context of AI, this question is not applicable. The device's functionality is based on programmed logic rather than learned patterns from data.

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