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The Somfit system is a non-invasive prescription device for home use with patients suspected to have sleep-related breathing disorders. The Somfit is a diagnostic aid for the detection of sleep-related breathing disorders, sleep staging (REM, N1, N2, N3, Wake), and snoring level. The Somfit system acquires electrical data from three frontal electrodes, triaxial accelerometer data, acoustic and plethysmographic data. The Somfit calculates and reports to clinicians EEG/EOG channels, Sleep Stages, SpO2, Peripheral Arterial Tonometry (PAT) signal, pulse rate, and snoring level. The Somfit calculates and reports to clinicians derived parameters such as PAT-derived Apnea Hypopnea Index, Obstructive Desaturation Index; and hypnogram-derived indices such as time in each sleep stage. Somfit data is not intended to be used as the sole or primary basis for diagnosing any sleep-related breathing disorder, prescribing treatment, or determining whether additional diagnostic assessment is warranted. The Somfit is not intended for use as life support equipment, for example vital signs monitoring in intensive care unit. The Somfit is a prescription device indicated for adult patients aged 21 years and over.

The Somfit is a home-based sleep monitoring device which records signals from the patient's forehead and surrounding environment. Somfit is a wearable, low voltage, battery operated device which is attached to subject forehead via a self-adhesive and disposable skin electrode patch. The electrodes are placed on the anterior Prefrontal cortex (PFC) at the Fp1 and Fp2 positions according to the 10/20 EEG system. The device allows for recording of two frontal EEG signals, pulse rate, SPO2, Peripheral Arterial Tonometry (PAT), PPG, motion, and snore. Somfit uses a mobile phone application to acquire data wirelessly via Bluetooth LE technology, then transfer into a secure cloud, for management, storage and postprocessing. The software reports measured parameters in a format compatible with AASM guidelines, including sleep time, pAHI and conventional graphical displays such as a hypnogram.

The Somfit device underwent rigorous testing to establish its performance against predefined acceptance criteria, particularly for its ability to detect sleep stages and related parameters.

Here's a breakdown of the acceptance criteria and the supporting study:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a formal "acceptance criteria" table with specific thresholds for each metric. However, the clinical performance section implicitly defines acceptance by demonstrating non-inferiority to the predicate device (Watch-PAT300) and superior or comparable performance against the gold standard (PSG) for key metrics.

Based on the provided text, here's a table summarizing the performance metrics that act as implicit acceptance criteria:

Implicit Acceptance Criteria & Reported Device Performance for Somfit

2. Sample Size and Data Provenance

• Test Set Sample Size: 92 subjects for the comparative clinical study involving Somfit, Watch-PAT300, and PSG.
• Data Provenance: The subjects were recruited from 3 site locations in Australia. The study was a prospective clinical study conducted to compare the devices' performance.

3. Number of Experts and Qualifications for Ground Truth

• Number of Experts: Three scoring sleep technologists.
• Qualifications of Experts: The document states they were "scoring sleep technologists." Specific educational background or years of experience are not provided, but their role implies expertise in polysomnography scoring.

4. Adjudication Method for the Test Set

The adjudication method for sleep staging ground truth was expert consensus. The PSG epochs were classified based on the "consensus of three scoring sleep technologists." This implies a form of 3-way consensus. Further details on how discrepancies were resolved (e.g., majority rule, discussion to reach agreement) are not provided.

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

No, a traditional MRMC comparative effectiveness study was not explicitly described in the provided text in the context of human readers improving with AI vs. without AI assistance. The study evaluated the device's performance (Somfit and Watch-PAT300) against a human-scored gold standard (PSG), rather than measuring the improvement of human readers assisted by AI. The Somfit system is described as a diagnostic aid that calculates and reports parameters to clinicians, implying that clinicians review the output, but the study design was not focused on measuring changes in human reader performance.

6. Standalone (Algorithm Only) Performance

Yes, the study primarily evaluated the standalone performance of the Somfit algorithm (and Watch-PAT300) in deriving parameters like pAHI and sleep stages, comparing its output directly to the gold standard PSG and the predicate device. There was no human-in-the-loop component as part of the evaluated performance for regulatory submission.

7. Type of Ground Truth Used

The primary ground truth used for the clinical study was Polysomnography (PSG), which is considered the gold standard technology for diagnosing sleep disorders. Specifically, for sleep staging, it was expert consensus-scored PSG data. For SpO2, it was gold standard SaO2 data obtained from an invasively controlled desaturation study.

8. Sample Size for the Training Set

The document does not provide information on the sample size for the training set for the Somfit algorithms. It focuses solely on the clinical validation/test set.

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

As the training set details are not provided, the method for establishing its ground truth is also not mentioned in the document.

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