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The Focus Diagnostics Simplexa™ Influenza A H1N1 (2009) assay is intended for use on the 3M Integrated Cycler as part of the Microfluidic Molecular System for the in vitro qualitative detection and differentiation of influenza A and 2009 H1N1 influenza viral RNA in nasopharyngeal swabs (NPS), nasal swabs (NS), and nasopharyngeal aspirates (NPA) from human patients with signs and symptoms of respiratory infection in conjunction with clinical and epidemiological risk factors.

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

Performance characteristics for influenza A were established during the 2009-2010 influenza season when 2009 H1N1 influenza was the predominant influenza A virus in circulation. When other Influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Simplexa™ Influenza A H1N1 (2009) test kit is a nucleic acid amplification test that uses real-time reverse transcriptase polymerase chain reaction (RT-PCR) amplification to enable simultaneous and distinct detection of influenza A and 2009 H1N1 influenza in a single reaction from nasophayngeal swabs (NPS), nasal swabs (NS), and nasopharyngeal aspirates (NPA). The assay combines real-time PCR amplification with fluorescent signal detection technology. A bi-functional fluorescent probe-primer is used together with a reverse primer to amplify a specific target (for each analyte and internal control). A fluorescent signal is generated after the separation of the fluorophore from the quencher as a result of the binding of a probe element to the extended RNA fragment synthesized during amplification.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio Software. Together, the instrument, software and test kit are referred to as the "Microfluidic Molecular System."

Here's a breakdown of the acceptance criteria and study details for the Simplexa™ Influenza A H1N1 (2009) assay based on the provided document:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a separate table with target values for clinical performance as commonly seen for medical devices. However, the reported performance metrics (Positive Percent Agreement - PPA, Negative Percent Agreement - NPA) from the clinical agreement studies serve as the de-facto acceptance criteria demonstrated by the device.

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

• Prospective Data:

  • Nasal/Nasopharyngeal Swabs: 299 specimens initially collected. After exclusions due to lack of consensus among reference assays (10 for Influenza A, 9 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 101
    • H1N1 Not Detected: 179
    • Influenza A Detected: 116
    • Influenza A Not Detected: 173
  • Nasopharyngeal Aspirates: 112 specimens initially collected. After exclusions due to lack of consensus among reference assays (5 for Influenza A, 3 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 24
    • H1N1 Not Detected: 80
    • Influenza A Detected: 31
    • Influenza A Not Detected: 76
  • Provenance: Collected from patients with signs and symptoms of influenza-like illness at three sites: Austin, TX (September 2009) and the New South Wales region of Australia (July - September 2009). The collected specimens were blinded and randomly distributed to 3 U.S. clinical laboratories for testing.

• Retrospective Data:

  • Nasal/Nasopharyngeal Swabs: 214 specimens initially collected from the Focus Sample Bank. After exclusions due to lack of consensus among reference assays (3 for Influenza A, 1 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 57
    • H1N1 Not Detected: 153 (including 1 indeterminate)
    • Influenza A Detected: 132 (including 1 indeterminate)
    • Influenza A Not Detected: 79
  • Nasal Washes: 2 specimens (both positive for 2009 H1N1 influenza and Influenza A by both methods).
  • Provenance: Focus Sample Bank (implying archival samples). No specific country of origin is mentioned beyond "Focus Sample Bank."

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

The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to a "composite reference method" which includes multiple validated assays, but not human expert review for establishing ground truth.

4. Adjudication Method for the Test Set

The ground truth was established using a composite reference method which included:

• Luminex xTAG RVP Flu A target
• A validated PCR assay using primer and probe sequences published by the CDC
• A well-characterized PCR followed by sequencing.

Specimens were excluded from analysis if there was "no consensus among the reference assays" for the influenza A result or if sequencing data was not available for subtyping. This implies a form of consensus/adjudication among the reference methods, but not by human experts in the traditional sense as a separate step.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed. This study evaluates the Simplexa™ Influenza A H1N1 (2009) assay in a standalone capacity against a composite reference (ground truth), not in comparison to or in assistance with human readers. Therefore, there is no effect size reported for human readers improving with AI vs without AI assistance.

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

Yes, this was a standalone performance study. The Simplexa™ Influenza A H1N1 (2009) assay's performance was evaluated by directly comparing its results to the established composite reference ground truth. There is no mention of human-in-the-loop involvement in the performance evaluation.

7. The Type of Ground Truth Used

The ground truth used was a composite reference method comprised of:

• Luminex xTAG RVP Flu A target
• A validated PCR assay using primer and probe sequences published by the CDC
• A well-characterized PCR followed by sequencing.

8. The Sample Size for the Training Set

The document does not explicitly mention a separate "training set" or its sample size for the development of the Simplexa™ Influenza A H1N1 (2009) assay. The provided studies focus solely on the performance of the developed assay, typically referring to validation or test sets.

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

Since a "training set" is not explicitly discussed, the method for establishing its ground truth is also not specified. It can be inferred that similar validated molecular methods would have been used during the assay's development phase.

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