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The PathoDx Respiratory Virus Panel (RVP) kit is a direct immunofluorescence test for the qualitative detection of 7 common respiratory viruses (respiratory syncytial virus, influenza A, influenza B, parainfluenza viruses 1,2, and 3, and adenovirus) in prepared direct patient specimens and following growth in cell culture. The materials supplied are intended for in vitro use only.

Direct immunofluorescence test for the qualitative detection of seven common respiratory viruses.

The PathoDx Respiratory Virus Panel kit consists of one screening reagent containing monoclonal antibodies to each respiratory virus and seven virus-specific monoclonal antibody reagents. All reagents contain monoclonal antibody labeled with fluorescein. Acetone-fixed cells from either patient specimens or cell culture are stained with the Screening Reagent and the Negative Control Reagent. The Screening Reagent contains fluorescein-labeled monoclonal antibodies to RSV, influenza A. influenza B. parainfluenza viruses 1, 2, and 3, and adenovirus. They will react specifically to any of the above viral antigens, if present in the cell. The Negative Control Reagent contains fluorescein-labeled murine antibodies which do not react with the viral agents. Unbound antibody and Evans blue counterstain are washed off with buffered saline, and the slide is mounted with buffered glycerol. Under fluorescence microscopy, the viral antigens recognized by the monoclonal antibodies present will show a characteristic apple-green fluorescence, while uninfected cells will counterstain red with Evans blue. To identify which of the seven respiratory viruses is reactive with the Screening Reagent, acetonefixed cell preparations are stained with each of the seven virus-specific reagents, washed free of unbound antibody, mounted with buffered glycerol, and observed under fluorescence microscopy. The responsible virus(es) will show characteristic apple-green fluorescence with uninfected cells counterstaining red.

1. A table of acceptance criteria and the reported device performance

The document does not explicitly state pre-defined acceptance criteria in terms of specific sensitivity, specificity, or agreement percentages. Instead, it presents the device's performance in comparison to reference methods and a predicate device. Based on the provided clinical performance data, the following table summarizes the device's performance:

Table of Device Performance

2. Sample sizes used for the test set and the data provenance

• Clinical Site 1, Study 1 (Direct Smear & Shell Vial):
  • Test Set Size: 200 specimens (150 fresh, 50 retrospective).
  • Data Provenance: Midwestern United States, a mix of prospective (fresh) and retrospective samples.
• Clinical Site 1, Study 2 (Cell Culture Isolates):
  • Test Set Size: 168 retrospective, frozen cell culture isolates (29 negative, 139 positive).
  • Data Provenance: Midwestern United States, retrospective.
• Clinical Site 2 (Direct Smear & Shell Vial):
  • Test Set Size: 185 fresh specimens (174 for direct smear, all 185 for shell vial).
  • Data Provenance: Midwestern United States, prospective.

3. 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 of experts or their qualifications for establishing the ground truth. The ground truth appears to be established by definitive cell culture procedures or comparison against predicate devices ("Kit A" and "Kit B"), which themselves represent established diagnostic methods.

4. Adjudication method for the test set

The document does not describe a formal adjudication method (e.g., 2+1, 3+1). The "ground truth" for the PathoDx device's direct smear performance in Clinical Site 1, Study 1, was definitive cell culture. For comparisons against predicate devices, "agreement" percentages are reported, implying direct comparison without an explicit adjudication process beyond the standard interpretation inherent in each method. For PathoDx direct smear versus cell culture, disagreements were individually detailed (e.g., 17 specimens negative by PathoDx but positive by cell culture were identified with specific viruses).

5. 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

A multi-reader multi-case (MRMC) comparative effectiveness study involving human readers and AI assistance was not performed. This device is a diagnostic immunoassay kit, not an AI-powered image analysis tool for human readers.

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

This question is not directly applicable as the PathoDx Respiratory Virus Panel is a direct immunofluorescence test kit, requiring human interpretation of fluorescence microscopy results. It is not an algorithm-only device. The performance data presented is for the test kit itself, which inherently involves human technicians performing the test and interpreting the results.

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

The primary type of ground truth used was:

• Definitive Cell Culture Procedure: This was explicitly used as the reference standard for evaluating the PathoDx direct smear performance in Clinical Site 1, Study 1.
• Predicate Device Results (Kit A and Kit B): For many comparisons, the results obtained from "Kit A" and "Kit B" (Bartels Viral Respiratory Screening and Identification Kit and Light Diagnostic Respiratory Viral Screen Indirect Immunofluorescence Assay by Chemicon International, Inc., respectively) served as the comparator or "reference" for calculating agreement. These predicate devices are themselves established diagnostic methods.

8. The sample size for the training set

The document does not mention a distinct "training set" for the PathoDx Respiratory Virus Panel. As a diagnostic reagent kit, its development would typically involve assay optimization and validation during manufacturing, rather than a machine learning-style training phase with a specific labeled dataset. The clinical studies described are for performance evaluation.

9. How the ground truth for the training set was established

Since no specific "training set" is mentioned in the context of machine learning, this question is not applicable. The development of such diagnostic kits relies on established virological principles, antibody specificity validation, and optimization of assay parameters, rather than ground truth establishment for a training dataset.

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