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The Quidel Molecular hMPV assay is a multiplex Real Time RT-PCR assay for the in vitro qualitative detection of human metapneumovirus RNA in nasal and nasopharyngeal swab specimens from patients with signs and symptoms of respiratory infection. This test is intended for use as an aid in the differential diagnosis of human metapneumovirus infections in humans in conjunction with clinical and epidemiological risk factors. This test is not intended to differentiate the four genetic sub-lineages of hMPV.

Negative results do not preclude hMPV infection and should not be used as the sole basis for diagnosis, treatment or other patient management decisions.

The Quidel Molecular hMPV Assay detects viral nucleic acids that have been extracted from a patient sample using the NucliSENS® easyMAG® automated extraction platform. A multiplex RT-PCR reaction is carried out under optimized conditions in a single tube generating amplicons for each of the target viruses present in the sample. This reaction is performed utilizing the Applied Biosystems 7500 Fast Dx platform. Identification of hMPV occurs by the use of target specific primers and a fluorescent- labeled probe that hybridizes to conserved regions in the RNA dependent RNA polymerase gene of hMPV.

Here's a summary of the acceptance criteria and study details for the Quidel Molecular hMPV Assay, based on the provided text:

Acceptance Criteria and Reported Device Performance

For the clinical study, performance was compared against an FDA-cleared RT-PCR comparator device. While explicit acceptance criteria ("Pass/Fail") are not stated in terms of specific percentages, the reported percentages (Positive Percent Agreement and Negative Percent Agreement) implicitly serve as the achieved performance against which the device's efficacy is judged.

Study Details

1. Sample sizes used for the test set and the data provenance:

   • Clinical Performance Test Set: N=1072 specimens (after excluding invalid results).
     • 742 fresh specimens: Collected for routine respiratory virus testing at thirteen sites across the United States.
     • 374 frozen specimens: Collected and tested at two geographically distinct locations.
   • Data Provenance: United States (multiple sites).
   • Retrospective/Prospective: The clinical study was prospective, conducted during the 2010-2011 respiratory virus season (January to March 2011).

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

   • The ground truth for the clinical performance test set was established by an "FDA Cleared RT-PCR" device (the comparator device, Gen-Probe Prodesse Pro hMPV+ (K082688)).
   • For 2 discrepant specimens that were positive by the Quidel Molecular hMPV assay but negative by the comparator, "sequence analysis" was used to resolve the discrepancy. The number and qualifications of experts for this sequence analysis are not specified in the provided text.

3. Adjudication method for the test set:

   • For the clinical performance study, direct comparison was made against the "FDA Cleared RT-PCR" device.
   • For the two discrepant cases where the Quidel assay was positive and the comparator was negative, "sequence analysis" was used as an adjudication method to determine the true state.

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:

   • No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This submission describes an in vitro diagnostic (IVD) assay where the "reader" is an automated instrument, not a human clinician interpreting images or data for diagnosis. Therefore, improvement of human readers with/without AI assistance is not applicable.

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

   • Yes, the performance characteristics described (analytical and clinical performance) represent the standalone performance of the Quidel Molecular hMPV Assay. It is an automated RT-PCR assay that provides a qualitative result (positive/negative) without human intervention in the interpretation of the primary result from the instrument.

6. The type of ground truth used:

   • Clinical Performance: "FDA Cleared RT-PCR" device (the predicate device) and, for discrepant cases, sequence analysis.
   • Analytical Performance (LoD, Inclusivity, Specificity): Quantified cultures of hMPV strains (TCID50/mL) for LoD and inclusivity, and specified concentrations of viral, bacterial, and yeast strains for specificity.

7. The sample size for the training set:

   • The provided document does not specify a separate training set size for the development of the Quidel Molecular hMPV Assay. This is common for molecular diagnostic kits, where the "training" involves optimizing primer/probe design and assay conditions, rather than training a machine learning algorithm on a specific data set.

8. How the ground truth for the training set was established:

   • As no specific "training set" in the machine learning sense is mentioned, information on how its ground truth was established is not provided. The development of this molecular assay would have involved standard molecular biology techniques, using characterized viral isolates and nucleic acid samples to optimize primer/probe sequences and reaction conditions, rather than a "ground truth" derived from patient data for an algorithm.

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