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The Visby Medical Respiratory Health Test is a single-use (disposable), fully integrated, automated Reverse Transcription Polymerase Chain Reaction (RT-PCR) in vitro diagnostic test intended for the simultaneous qualitative detection and differentiation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A, and influenza B RNA in nasopharyngeal swab and anterior nasal swab specimens from individuals with signs and symptoms of respiratory tract infection. Clinical signs and symptoms of respiratory tract infection due to SARS-CoV-2, influenza A, and influenza B can be similar.

The Visby Medical Respiratory Health Test is intended for use as an aid in the differential diagnosis of SARS-CoV-2, influenza A, and influenza B infection if used in conjunction with other clinical and epidemiological information, and laboratory findings. SARS-CoV-2, influenza A, and influenza B viral RNA are generally detectable in nasopharyngeal swab and anterior nasal swab specimens during the acute phase of infection. This test is not intended to detect influenza C virus infections.

Positive results are indicative of the identified virus, but do not rule out bacterial infection or co-infection with other organisms not detected by the test. The agent(s) detected by the Visby Medical Respiratory Health Test may not be the definitive cause of disease. Negative results do not preclude SARS-CoV-2, influenza A, or influenza B infection. The results of this test should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

The Visby Medical Respiratory Health Test is a single-use (disposable), fully integrated, compact device containing a reverse transcription polymerase chain reaction (RT-PCR) based assay for qualitative detection of influenza B, and/or SARS-CoV-2 viral RNA in upper respiratory tract specimens. The device automatically performs all steps required to complete lysis, reverse transcription (RT), PCR amplification, and detection.

Specimen collected using nasopharyngeal (NP) or anterior nasal (AN) swabs (without transport media) are placed in the Visby Medical Respiratory Health Buffer and then transferred into the sample port of the device using the provided fixed volume pipette. The sample enters a lysis module and rehydrates the RT enzyme and RT primers. The mixture then moves through a sample preparation module where viruses and human cells are simultaneously lysed, and RNA is reverse transcribed. The resulting fluid (containing cDNA) is then mixed with lyophilized PCR reagents containing the DNA polymerase enzyme and PCR primers. The PCR mixture (containing cDNA template and reagents) is then thermal cycled to amplify the targets, including human beta-2 microglobulin (B2M) RNA, which serves as a process control. After PCR, the biotinylated product is hybridized to covalently bound capture probes at specific locations along a flow channel. The flow channel is configured to facilitate an enzymatic reaction that uses streptavidin bound horseradish peroxidase (HRP) and a colorimetric substrate that forms a purple precipitate. The operator observes a color change at the specific locations indicating the presence of an amplified target. Test results can be expected in approximately 30 minutes: illumination of a "DONE" status light on the front of the device and a purple color in the "RESULTS VALID" spot, indicate a successful test. A purple spot adjacent to "Flu A", "Flu B", and/or "COVID-19" signifies the presence of, influenza A, influenza B, and/or SARS-CoV-2 viral RNA.

Here's an analysis of the acceptance criteria and study detailed in the provided text:

Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a separate table. However, based on the Summary of Performance Data, the inferred acceptance criteria are the achieved Positive Percentage Agreement (PPA) and Negative Percentage Agreement (NPA) values in the clinical evaluation. The study aims to demonstrate substantial equivalence to the predicate device, implying that the performance needs to be comparable or better.

Here's a table summarizing the reported device performance, which implicitly represents the met acceptance criteria:

Study Details:

• Sample size used for the test set and the data provenance:

  • Sample Size: A total of 1,501 subjects were included in the performance analysis after exclusions. 1,575 Visby tests were initially performed.
  • Data Provenance: Prospectively collected fresh specimens from subjects presenting with signs and symptoms of a viral respiratory infection at five CLIA Waived study sites in the US (urgent care and family care clinics). Specimens were collected and tested between May 2022 and Feb 2024.

• Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

  • The document does not specify the number or qualifications of experts used to establish ground truth for the test set. Instead, it states that the comparator assays define the ground truth.

• Adjudication method (e.g., 2+1, 3+1, none) for the test set:

  • The document describes comparing the Visby Medical Respiratory Health Test results against an "FDA-cleared influenza molecular test and an FDA-EUA authorized SARS-CoV-2 RT-PCR test as a comparator." It also mentions "alternate molecular assay" for discordant results (footnotes a, b, e, f, g, h, i, j in Table 2). This indicates that the ground truth was established by these comparator assays, potentially with some form of reference-standard-based comparison and possibly resolution of discrepancies with alternate assays, rather than a multi-expert adjudication method on the test set itself.

• 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 comparative effectiveness study was not done. This device is an in vitro diagnostic (IVD) test for molecular detection of viruses, not an AI-assisted diagnostic imaging or human-read interpretation system. The "operators" in the reproducibility study were "non-laboratorians representing healthcare professionals," but their performance was evaluated against expected results for spiked samples, not in comparison to their own performance with and without an AI assistant on clinical cases.

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

  • Yes, a standalone performance evaluation was primarily done for the device. The clinical study evaluated the device's ability to detect viral RNA in specimens. While "typical CLIA Waived operators" performed the test, their role was to execute the device's protocol, and the device's detection accuracy was then compared against the comparator assays. The "device automatically performs all steps required to complete lysis, reverse transcription (RT), PCR amplification, and detection," implying it functions as a standalone diagnostic unit once the sample is loaded.

• The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

  • The ground truth for the clinical evaluation was established by comparator molecular assays: an "FDA-cleared influenza molecular test" and an "FDA-EUA authorized SARS-CoV-2 RT-PCR test." Discordant results were sometimes further investigated with an "alternate molecular assay."

• The sample size for the training set:

  • The document does not specify a separate training set or its sample size. For IVD devices like this RT-PCR test, the "training" typically refers to the assay development and optimization process in the lab, rather than a distinct training set in the way AI/ML models are trained. The clinical performance study evaluates the final, optimized device.

• How the ground truth for the training set was established:

  • As no distinct "training set" in the context of an AI/ML model is described, this information is not applicable. The development and optimization of such a diagnostic test would involve analytical studies (e.g., LoD, inclusivity, cross-reactivity) where the "ground truth" for those specific experiments (e.g., known concentrations of viral targets) is established by careful spiking and molecular characterization in a laboratory setting.

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