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The Thermo BioStar™ FLU OIA* A/B assay is an Optical ImmunoAssay test for the qualitative, rapid detection of influenza A and B viral antigens (nucleoproteins) extracted from nasal aspirate, nasopharyngeal swab, throat swab, and sputum specimens. This test is intended for in vitro diagnostic use to aid in the differential diagnosis of influenza A and B viral infections. The FLU OIA A/B test is not intended for detection of influenza C. Negative test results should be confirmed by cell culture.

The FLU OIA A/B test involves the extraction and detection of a protein antigen unique to influenza A or B (nucleoprotein). The Optical ImmunoAssay technology enables the direct visual detection of a physical change in the optical thickness of molecular thin films. This change is a result of antigen-antibody binding on an optical surface (silicon wafer). When an extracted specimen is placed directly on the optical surface, the immobilized specific antibodies capture the antigen. After washing, the substrate is added, increasing the thickness (mass enhancement) of the molecular thin film. This change in thickness alters the reflected light path and is visually perceived as a color change. Slight changes in optical thickness produce a distinct, visible color change. A positive result appears as a purple spot on the predominant gold background. When antigen is not present in the specimen, no binding takes place. Therefore, the optical thickness remains unchanged and the surface retains the original gold color indicating a negative result.

Here's an analysis of the provided text regarding the acceptance criteria and study for the FLU OIA® A/B device, structured according to your requested information:

Acceptance Criteria and Device Performance Study for FLU OIA® A/B

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state pre-defined acceptance criteria values for sensitivity or agreement. The reported device performance is presented as the study outcome without direct comparison to a specified target. However, the FDA's clearance of the device implies these performance metrics were deemed acceptable.

2. Sample Size and Data Provenance for Test Set

• Sample Size:

  • Clinical Sample Comparison: 184 patients enrolled in a multi-center study. Data available for analysis included 151 specimens positive by culture (129 Influenza A, 22 Influenza B).
  • Comparison to original FLU OIA: 112 retrospective frozen clinical specimens.
  • Reproducibility (Inter-Laboratory): Not explicitly stated as a single number for samples, but "Individual panels were prepared, each containing nine blinded specimens and two controls." This was performed on "three different occasions" by "four different laboratories."
  • Reproducibility (Intra-Laboratory): Not explicitly stated as a single number, but "testing specimens at or near the cut-off in multiple replications (n=20)."

• Data Provenance:

  • Clinical Sample Comparison: Multi-center study with geographically diverse clinical sites. The data is retrospective, as it's a "retrospective analysis of previously collected clinical data."
  • Comparison to original FLU OIA: Retrospective frozen clinical specimens.
  • Reproducibility: Not specified beyond "three POL or clinic sites, and one internal Thermo BioStar site." The specimens for reproducibility were "spiked with negative, low positive, moderate positive, and high positive specimens for each virus type."

3. Number of Experts and Qualifications for Ground Truth

• The document does not explicitly state the number or qualifications of experts used to establish the ground truth.
• The ground truth for the clinical sample comparison relied on "commercially available cell culture, with confirmation and typing by fluorescent antibody staining." This implies laboratory personnel with expertise in viral culture and fluorescent antibody staining were involved, but their specific qualifications or number are not detailed.

4. Adjudication Method for Test Set

• The document does not describe any specific adjudication method (e.g., 2+1, 3+1). The ground truth was established by "commercially available cell culture, with confirmation and typing by fluorescent antibody staining."

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

• No, a MRMC comparative effectiveness study was not conducted. This device is an in-vitro diagnostic (IVD) test, not an imaging or AI-assisted diagnostic tool for human readers. Its performance is compared to a historical reference method (viral culture) or a predicate device, not in terms of human reader improvement with AI assistance.

6. Standalone Performance Study

• Yes, a standalone performance study was conducted. The performance characteristics for the FLU OIA® A/B (and the original FLU OIA) were established by comparing the device's output (positive/negative for Influenza A/B) directly against the ground truth (viral culture and fluorescent antibody staining). The reported sensitivities are standalone performance metrics.

7. Type of Ground Truth Used

• The primary ground truth used for the clinical sample comparison was viral culture, with confirmation and typing by fluorescent antibody staining.

8. Sample Size for Training Set

• The document does not mention a separate "training set" in the context of machine learning or AI. This device is an optical immunoassay, which does not typically involve training on datasets in the same way an AI algorithm would. The "Performance characteristics for the original AB FLU OIA assay were initially established in a multi-center study" but this refers to the initial validation of the technology, not a training set for a learning algorithm. Subsequent comparability studies were performed using "inactivated virus standards, live virus strains, and a panel of retrospective frozen clinical specimens."

9. How Ground Truth for Training Set Was Established

• As noted above, a "training set" in the context of an AI algorithm is not applicable here. For the "Performance characteristics for the original AB FLU OIA assay," the ground truth would have been established through methods such as viral culture, as detailed for the clinical sample comparison. The comparability studies also relied on "inactivated virus standards" and "live virus strains" where the viral status would be known.

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