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The Gastric Alimetry System is intended to record, store, view and process gastric myoelectrical activity as an aid in the diagnosis of various gastric disorders.

The Gastric Alimetry System is an electrogastrography (EGG) device, used for non-invasively measuring the myoelectrical activity of the stomach at the surface of the abdomen. The Gastric Alimetry System is intended to record, store, view and process gastric myoelectrical activity as an aid in the diagnosis of various gastric disorders.

The device is used to acquire and digitize gastric myoelectrical data and movement artifacts using an array with recording electrodes on an adhesive patch. which is used for recording the myoelectrical data from the skin surface. An App is used to set up the device and capture patient-reported symptom data. A report is provided to the clinicians at the test which includes myoelectrical signal data for manual analysis, together with computed data summaries and plots. A Supplementary Report is also routinely available to clinicians that includes signal data from all 64 channels on the array.

In the modified Gastric Alimetry System, the following minor updates are introduced in order to provide additional data summaries within the Report:

• Addition of four post-processing data summary metrics:
  • Principal Gastric Frequency showing the frequency of myoelectrical activity o occurring within the gastric range
  • 'BMI-Adjusted Amplitude' calculated amplitude for BMI up to the recommended O device limit (BMI <35)
  • Gastric Alimetry Rhythm Index a calculated measure of the stability of the gastric о rhythm
  • fed:fasted Amplitude Ratio a calculated ratio showing the change in the gastric o myoelectrical amplitude after a meal stimulus.
• Addition of a 'Symptom Burden' tracking bar to the front page of the Report. This is a ● calculated average of the patient-reported symptom data already shown in the Report, and is provided as a summary next to the spectral plot as a convenience for clinicians.
• Addition of data tables to the Supplementary Report. These provide hour by hour read ● outs of the symptom logs and summary metrics provided in the main Report, and are made available in Table form as a convenient reference for clinicians.
• Some minor Report rearrangements, with the 'signal strength' and 'best 8 channel' plots . moved from the main Report to the Supplementary Report.

The four additional metrics are equivalent to other metrics widely applied in the EGG literature, and are included in the Reference Device, with only minor updates that address recognized inaccuracies that may affect performance.

Based on the provided text, the Gastric Alimetry System is an electrogastrography (EGG) device. The performance data section focuses on demonstrating the substantial equivalence of four newly added data summary metrics to equivalent metrics in a Reference Device (Medtronic Polygram NET EGG System), rather than establishing new acceptance criteria for the entire device.

Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:

Acceptance Criteria and Reported Device Performance

The acceptance criteria here aren't typical performance thresholds (like achieving a certain sensitivity or specificity for a diagnostic claim). Instead, the "acceptance criteria" for the newly added metrics in the modified Gastric Alimetry System appear to be demonstrating high correlation with equivalent metrics from a legally marketed Reference Device. The aim is to prove substantial equivalence, meaning these minor updates do not raise new questions of safety or effectiveness.

Study Details:

1. A table of acceptance criteria and the reported device performance:
   (See table above)

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

   • Sample Size: 86 subjects (43 patients with chronic nausea and vomiting syndromes, gastroparesis, and functional dyspepsia, and 43 healthy matched controls).
   • Data Provenance: "post-market data from a study". The text does not specify the country of origin or if it was retrospective or prospective, beyond "post-market". It implies existing collected data.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g., radiologist with 10 years of experience):
   The text does not mention the use of experts to establish a "ground truth" for the test set in the context of this performance study. The study's purpose was to compare the new metrics to existing, approved metrics, not to validate diagnostic accuracy against a clinical ground truth. The "ground truth" in this comparative study context is the output of the Reference Device's equivalent metrics.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set:
   Not applicable. This study was a direct comparison of computational metrics between two systems (the modified device's metrics vs. the reference device's metrics), not a human-in-the-loop diagnostic study requiring expert 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, an MRMC study was not done. The device (Gastric Alimetry System) is described as an EGG device that "provides additional data summaries within the Report" and "includes myoelectrical signal data for manual analysis, together with computed data summaries and plots." While it processes data, it isn't an AI-based diagnostic tool in the typical sense that would assist human readers in image interpretation or diagnosis. The study focused on the equivalence of the calculated metrics themselves, not on how they might improve human interpretation.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
   Yes, in a sense. The comparison was of the computational output of the new metrics from the Gastric Alimetry System directly against the computational output of the equivalent metrics from the Reference Device. This is an "algorithm only" comparison for these specific metrics. The device itself is not presented as a fully automated diagnostic algorithm but rather a system that aids diagnosis by providing data and summaries for manual analysis.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
   The "ground truth" for the purpose of this equivalence study was the output of the equivalent metrics from the accepted Reference Device (Medtronic Polygram NET EGG System). It was a comparative validation, not a validation against a clinical gold standard like pathology or long-term outcomes for diagnostic accuracy.

8. The sample size for the training set:
   Not mentioned. The description of the performance data focuses solely on a "test set" or "comparison cohort" for demonstrating equivalence of the new metrics. Since the changes are described as "minor updates" to address "recognized inaccuracies" and the goal is "substantial equivalence" to a predicate, it's possible that the development of these metrics leveraged existing physiological knowledge and signal processing techniques rather than a large machine learning training set as might be seen for a novel AI algorithm.

9. How the ground truth for the training set was established:
   Not applicable, as no training set or ground truth for a training set is discussed for these specific updates.

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