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The Ouell-FM is a transcutaneous electrical nerve stimulation (TENS) device indicated as an aid for reducing the symptoms of fibromyalgia in adults with high pain sensitivity. The Quell-FM may be used during sleep. The Quell-FM is labeled for use only with compatible NeuroMetrix electrodes.

Ouell-FM is a wearable, transcutaneous electrical nerve stimulator designed to stimulate sensory nerves in the upper-calf region. The device utilizes a microprocessor running embedded software and a custom high-voltage Application Specific Integrated Circuit (ASIC) to generate current regulated stimulating pulses with specific characteristics including pulse shape, amplitude, duration, pattern, and frequency. The device utilizes Bluetooth® low energy (BLE) to communicate with a mobile device that allows the user to start and stop therapy, control stimulation intensity, and modify certain operating characteristics. The device is powered by an embedded rechargeable lithium-ion polymer battery that is charged through a USB cable connected to an AC adapter.

The primary components of the device include the Quell-FM device, Band, Electrodes, and Quell-FM mobile app.

• A. Quell-FM Device
  The Quell-FM device delivers electrical stimulation to the user through a disposable electrode placed on the user's body. The Quell-FM is labeled for use only with compatible NeuroMetrix electrodes (previously cleared in K140586), to which it connects through insulated female medical snap connectors embedded within its housing; no lead-wires are used.

• B. Band
  A flexible band secures the Quell-FM device and the electrode to the user's leg using a hook and loop material.

• C. Electrodes
  The Quell-FM device is labeled for use only with compatible NeuroMetrix electrodes (i.e., electrodes cleared under K140586). This use specification, in part, ensures the safe use of the device during sleep because NeuroMetrix electrodes have a known surface area that allows the device to quantitively determine relative skin contact area. Stimulation will be automatically stopped if device detects a decrease in skin-contact area which may lead to unsafe current density to be delivered as would occur during unattended use such as sleeping.

• D. Quell-FM Mobile App
  Quell-FM is used with a mobile app, running on an iOS or Android mobile device, to which it communicates via Bluetooth. Using the mobile app, the user can start and stop the therapy, control stimulation intensity, and modify certain operating characteristics.

The provided document describes a clinical study to evaluate the effectiveness and safety of the Quell-FM device, a transcutaneous electrical nerve stimulator for fibromyalgia symptoms. Here's a breakdown of the acceptance criteria and the study that proves the device meets those criteria:

Acceptance Criteria and Reported Device Performance

The acceptance criteria for the Quell-FM device are primarily demonstrated through its clinical effectiveness in reducing fibromyalgia symptoms and its safety profile. While explicit "acceptance criteria" in a pass/fail table format aren't directly provided for clinical endpoints (as would be typical for an AI/algorithm-based device), the successful grant of the De Novo request implies that the FDA found the following evidence acceptable for product classification. The "reported device performance" reflects the key findings from the clinical study.

Study Information

This document describes a clinical trial, not directly an AI/algorithm performance study in the typical sense with a "test set" and "ground truth" derived from expert consensus on images. Instead, it's a randomized controlled trial designed to assess clinical efficacy. Therefore, some of the requested points related to AI/algorithm testing (e.g., number of experts for ground truth, MRMC study, standalone performance) are not directly applicable or are interpreted within the context of a clinical trial.

1. Sample Size Used for the Test Set and Data Provenance:

   • Test Set Sample Size: 119 subjects were randomized: 62 to the active group and 57 to the sham group.
   • Data Provenance: The study was a "double-blind, randomized, sham-controlled trial," implying prospective data collection in a clinical setting. The country of origin of the data is not explicitly stated, but the mention of the American College of Rheumatology 2010 diagnostic criteria and the FDA De Novo request suggest the study was conducted in the United States and used patients primarily from that region.

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

   • Context: This question is not directly applicable in the sense of establishing "ground truth" for an AI algorithm's diagnostic performance from expert reads (e.g., radiologist interpreting an image). Instead, the "ground truth" for clinical efficacy in this trial is derived from objective and subjective patient-reported outcomes (PROs) and clinical assessments.
   • Expert involvement was in:
     • Diagnosis: Inclusion criteria required a "physician diagnosis of fibromyalgia in the medical record" based on American College of Rheumatology 2010 criteria. The specific number and qualifications of these diagnosing physicians are not detailed in the document but would generally be rheumatologists or pain specialists.
     • Clinical Assessments: Study endpoints relied on standardized questionnaires (e.g., PGIC, FIQR, BPI) and quantitative sensory testing (QST).
     • Adverse Event Assessment: The principal investigator assessed the relatedness of adverse events to TENS use. Qualifications of the principal investigator are not specified but are implied to be a medical professional.

3. Adjudication Method for the Test Set:

   • Context: Adjudication is not applicable in the typical sense of resolving discrepancies between multiple expert readings for image interpretation.
   • Clinical Trial Design: The clinical trial used a double-blind, randomized, sham-controlled design. This design inherently controls for bias by blinding both subjects and study coordinators to the treatment allocation. Blinding effectiveness was assessed at the end of the study.
   • Statistical Analysis: Missing data for effectiveness measures were handled by single imputation for the primary endpoint and multiple imputation for secondary endpoints. Significance was assessed by two-sample t-tests within an ANCOVA model.

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 study is a clinical trial evaluating the effectiveness of a medical device (TENS) on fibromyalgia symptoms, not an AI algorithm. Therefore, there are no "human readers" or "AI assistance" in this context. The study compares the device (active treatment) directly against a sham device.

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

   • Not applicable. This device is a transcutaneous electrical nerve stimulator, a physical device that delivers electrical stimulation to a patient. It is not an AI algorithm, nor does it operate in a "standalone" algorithmic sense from a diagnostic or interpretative perspective. Its performance is measured by its physiological impact on patients.

6. The Type of Ground Truth Used:

   • Clinical Ground Truth: The ground truth for effectiveness was established through patient-reported outcomes (PROs) and objective measures of fibromyalgia symptoms and their impact, as defined by validated clinical questionnaires and quantitative sensory testing.
     • Primary Endpoint: Patient's Global Impression of Change (PGIC) - a subjective patient assessment.
     • Secondary Endpoints: Fibromyalgia Impact Questionnaire Revised (FIQR), Brief Pain Inventory Short Form (BPI), painDETECT Questionnaire (PDQ), Pain Disability Index (PDI), Hospital Anxiety and Depression Scale (HADS), Pain Catastrophizing Scale (PCS) - a mix of subjective patient reports and derived scores.
     • Subgroup Analysis: Quantitative Sensory Testing (QST) at baseline was used to subgroup patients by pain sensitivity. This involved objective measurements of responses to mechanical and cold stimuli.
   • Safety Ground Truth: Established through reported adverse events and their assessment by the principal investigator and through compliance with recognized safety standards (biocompatibility, electrical safety, EMC, software V&V).

7. The Sample Size for the Training Set:

   • Not applicable. This was a clinical trial of a medical device, not a machine learning model. Therefore, there was no separate "training set" for an algorithm. The 119 subjects served as the study population for evaluating the device's efficacy and safety.

8. How the Ground Truth for the Training Set was Established:

   • Not applicable. As there was no training set for an AI/algorithm, this question is not relevant to this clinical trial. The "ground truth" for the overall study's clinical endpoints was established as described in point 6.

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