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The Cala Trio device is indicated to aid in the temporary relief of hand tremors in the treated hand following stimulation in adults with essential tremor.

Cala Trio is a small, lightweight, wrist-worn stimulator device designed to aid in essential tremor symptom relief by applying Transcutaneous Afferent Patterned Stimulation (TAPS) to the median and radial nerves of a patient's wrist. The Cala Trio system includes three main components: (1) a rechargeable stimulator, (2) a wrist-worn electrode band, and (3) a base station that charges the device.

The stimulator component contains the electronics for delivering TAPS to the patient's wrist. There are three buttons on the stimulator that are used for calibration and stimulation amplitude adjustments, among other functions. Text prompts, stimulation delivery parameters, timer, and other messages are provided on the stimulator's full color display to provide instructions and stimulation delivery information.

To deliver therapy, the stimulator is attached to the wrist band, which includes integrated electrodes placed at appropriate intervals around the inner diameter of the band to properly target the median and radial nerves. To accommodate a broad distribution of wrist sizes, the band is available in three sizes (small, medium, and large). Each band size is also available in right or left-handed versions to target the appropriate nerves of the prescribed hand.

The provided text describes a 510(k) premarket notification for a medical device called Cala Trio. This submission focuses on demonstrating substantial equivalence to a previously cleared predicate device, Cala ONE, rather than establishing de novo performance criteria for an entirely new device. Therefore, the "acceptance criteria" discussed are primarily about demonstrating that the modified device (Cala Trio) is as safe and effective as the predicate device (Cala ONE), despite some changes.

Here's an analysis of the provided information concerning the "acceptance criteria" and the study that proves the device meets them, structured according to your request:

1. Table of Acceptance Criteria and Reported Device Performance

Since this is a substantial equivalence submission, the "acceptance criteria" are not absolute performance targets set for a new device type, but rather the demonstration that the Cala Trio performs equivalently to the Cala ONE. The performance here is primarily about achieving similar clinical outcomes and meeting non-clinical safety/electrical standards.

Study 2 (Yu et al., 2020 - single session): 70-80% of TAPS users demonstrated tremor relief for 60 minutes after stimulation in a study of 15 participants. |
| Non-clinical & Technical Equivalence: | |
| Biocompatibility in accordance with ISO 10993-1. | Demonstrated Biocompatibility in accordance with ISO 10993-1:2018 (Cala ONE was 2009 version). |
| Meets IEC60601-1 and collateral standards (EMC & Electrical Safety). | Meets all requirements of IEC60601-1 and relevant collateral and particular standards. |
| Stimulation waveform conforms to internal standard. | Stimulation waveform conforms to requirements of internal standard test method and acceptance criteria. |
| Electrode performance and shelf life. | Electrode performance conforms to requirements of internal standard test method and acceptance criteria at T=24 months. |
| Sensor performance and associated algorithms. | Non-clinical performance testing demonstrated that the measurements obtained from the Cala Trio sensor (triaxial accelerometer only) are equivalent to those obtained from the Cala ONE sensors (gyroscope and triaxial accelerometer). |
| Electrical stimulation characterization. | The therapy pattern parameters are unchanged, and clinical evidence demonstrates that changes in maximum output voltage, maximum output current, maximum phase charge, maximum current density, maximum average current, and maximum average power density do not impact safety or effectiveness of the device. The functionality of the output channel and therapy parameters are unchanged despite going from 1 channel with 2 alternating outputs to 2 alternating channels. |

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

• Isaacson et al. (2020) Study:
  • Sample Size: 263 enrolled subjects, with 205 subjects completing the study.
  • Data Provenance: Not explicitly stated, but described as a "prospective, multi-center, single-arm three months study of repeated home use." Given the authors and typical clinical trial landscapes for such devices, it's highly likely to be US-based, and it is prospective.
• Yu et al. (2020) Study:
  • Sample Size: 15 participants.
  • Data Provenance: Described as "an in-office, single session study." Not explicitly stated, but likely also prospective and US-based given the authors.

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

The document does not describe the establishment of a "ground truth" by experts in the way it might for an AI image analysis device (e.g., radiologists labeling images). Instead, the performance is assessed via:

• Patient self-reported outcomes: PGI-I (Patient Global Impression of Improvement).
• Clinician-reported outcomes: CGI-I (Clinical Global Impression of Improvement).
• Standardized tremor assessment scales: TETRAS (The Essential Tremor Rating Assessment Scale) and BF-ADL (Bain and Findley Activities of Daily Living Scale).
• QUEST (Quality of Life in Essential Tremor) scale.

For the clinician-reported outcomes, while not specified, it's presumed that the clinicians involved in the multi-center study were qualified medical professionals, likely neurologists or specialists in movement disorders, who are trained to assess these scales. The number of such "experts" would correspond to the number of clinicians participating in the study who performed these assessments. The document does not specify the exact number of clinicians or their precise qualifications beyond what is implied by their role in a clinical study for essential tremor.

4. Adjudication Method for the Test Set

No explicit adjudication method (like 2+1 or 3+1 consensus) is described for the clinical outcome measures. These measures (TETRAS, BF-ADL, CGI-I, PGI-I, QUEST) are often collected directly by study staff, clinicians, or patients, and then analyzed statistically. It is not an image review or labeling task that typically requires adjudication.

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

No MRMC study was performed or is relevant here, as this device (Cala Trio) is a therapeutic device for tremor relief, not an AI diagnostic imaging tool interacting with human readers.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done

The Cala Trio is a physical therapeutic device. Its core function is to deliver transcutaneous afferent patterned stimulation (TAPS). Its performance is inherently "standalone" in the sense that the device itself delivers the therapy. There is no human-in-the-loop performance being evaluated in the context of an algorithm's output needing interpretation by a human. The patient uses the device, but the device's therapeutic action is direct.

7. The Type of Ground Truth Used (Expert Consensus, Pathology, Outcomes Data, etc.)

The "ground truth" in this context refers to the assessment of tremor relief and improvement in daily living and quality of life. This was established using:

• Clinical Assessment Scales: TETRAS, BF-ADL (Likely assessed by clinicians).
• Patient-Reported Outcomes: PGI-I, QUEST (Self-reported by patients).
• Clinician Global Impression of Improvement: CGI-I (Assessed by clinicians).
• Self-reported duration of tremor relief from patients.

This is a combination of subjective patient feedback and objective (clinical scale scores) assessments.

8. The Sample Size for the Training Set

This document describes a 510(k) submission for a device modification, relying on clinical evidence of its direct predecessor (Cala ONE) and clinical studies of the modified device (Cala Trio) for substantial equivalence. It does not refer to a machine learning context where a separate "training set" would be used to develop an algorithm for diagnosis or image analysis. The "training" for the device's therapeutic protocol was established in prior research for the Cala ONE and maintained for the Cala Trio.

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

As above, this context is not applicable. The device's therapeutic mechanism (TAPS) is based on established neurophysiological principles, not on a machine learning model trained on a dataset with a defined "ground truth" in the AI sense. The clinical studies establish the device's effectiveness, not a training ground truth for an algorithm.

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