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The Platelia® Toxo IgG TMB kit is an in-vitro diagnostic test kit for the qualitative and quantitative detection of anti-Toxoplasma gondii IgG in human serum or plasma (EDTA, Heparin, Citrate).

Note: The Platelia® Toxo IgG TMB assay has not been cleared/approved by the FDA for blood/plasma donor screening.

The Platelia® Toxo IgG TMB assay utilizes a solid-phase enzyme immunoassay technique referred to as an indirect ELISA. Diluted test samples are placed into the T. gondii antigen coated wells of the microplate. During incubation, T. gondii antibodies present in the test sample bind to the T. gondii antigen. After incubation, unbound antibodies and other serum proteins are removed by washing. The conjugate (peroxidase-labeled monoclonal antibody specific for human gamma chains) is added to the micropalte wells. During a second incubation, the labeled monoclonal antibody binds to the IgG antibody – T. gondii antigen complexes attached to the microplate wells. The unbound conjugate is removed by washing. The addition of peroxidase substrate and chromogen solutions initiates a color development reaction. The enzymatic reaction is stopped by addition of an acid. The optical density reading, obtained with a spectrophotometer set at 450nm, is proportional to the amount of T. gondii IgG antibody present in the test sample and is converted into IU/ml using a standard curve. Standard control sera are calibrated against the WHO standard (TOXM185).

This document describes the performance of the Bio-Rad Laboratories Platelia® Toxo IgG TMB assay, an in-vitro diagnostic test kit for the qualitative and quantitative detection of anti-Toxoplasma gondii IgG in human serum or plasma.

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state pre-defined acceptance criteria with pass/fail thresholds. However, it provides performance data from comparison studies and CDC test panel results, which can be interpreted as demonstrating the device's acceptable performance against a predicate device and a characterized serum panel.

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

• Comparison Studies:
  • Prospective samples: 468
  • Retrospective specimens (seroconversion panels): 35 from 11 seroconversion panels.
  • Total Test Set Size: 503 samples (468 prospective + 35 retrospective).
  • Data Provenance: Not explicitly stated for all samples. The "Expected Values" section mentions 503 fresh and frozen serum samples from pregnant women obtained during routine laboratory activities in Paris, France. It is highly probable that the prospective samples for the comparison study are these samples from Paris, France. The provenance of the retrospective seroconversion panels is not specified, but they are typically commercially available panels.
• CDC Test Panel:
  • 70 positive and 30 negative samples.
  • Data Provenance: Obtained from the CDC.

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

The document does not explicitly state the number of experts or their qualifications for establishing ground truth.

• For the comparison studies, the ground truth was established by another commercially available enzyme immunoassay (EIA), implying accepted diagnostic methods. No human experts are mentioned as directly establishing this ground truth for each case individually.
• For the CDC Test Panel, the samples were "masked, characterized serum panel." This implies that the CDC (Centers for Disease Control and Prevention) had previously characterized these samples, establishing their positive or negative status for Toxoplasma gondii IgG. While this characterization would have been performed by experts, their specific number and qualifications are not provided within this document.

4. Adjudication Method for the Test Set:

Not applicable. The ground truth for the comparison study was based on another commercial EIA, and the CDC panel was a pre-characterized panel. There is no mention of a human adjudication process for resolving discordant results during these evaluations. Discrepancies (e.g., 5 equivocal and 1 positive result in the negative category, 3 equivocal and 3 positive results in the equivocal category from the predicate in the "Platelia® Toxo IgG TMB vs OPD Correlation Table") were simply reported and then excluded from agreement calculations, rather than being subjected to a specific adjudication process described in the document.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done:

No, an MRMC comparative effectiveness study was not done. The studies described are focused on the device's performance characteristics (precision, comparison to another EIA, and agreement with a CDC panel) rather than assessing human reader performance with and without AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:

Yes, a standalone study was done. The document describes the performance of the Platelia® Toxo IgG TMB assay (an indirect ELISA, which is an automated or semi-automated laboratory device) as an algorithm-only without human-in-the-loop performance. The results are based on the device's output (optical density converted to IU/ml) compared against reference methods.

7. The Type of Ground Truth Used:

• Comparison Studies: The ground truth was based on the results of another commercially available enzyme immunoassay (EIA).
• CDC Test Panel: The ground truth was based on results from a masked, characterized serum panel obtained from the CDC, implying established reference methods used by the CDC.
• Precision Studies: The ground truth was based on known negative and positive samples, which are internally characterized for reproducibility assessment.

8. The Sample Size for the Training Set:

The document describes a diagnostic assay (ELISA kit) rather than a machine learning or AI-based device that typically requires a 'training set.' Therefore, the concept of a training set as understood in AI/ML is not applicable here. The device's calibration and internal validation would rely on standard laboratory procedures and reference materials, but not an "AI training set."

9. How the Ground Truth for the Training Set Was Established:

As explained above, the concept of a "training set" in the context of an ELISA kit is not directly applicable. The device's operational parameters would be established during its development and manufacturing using internal quality control and reference standards. The standard control sera used for calibration (mentioned as being calibrated against the WHO standard TOXM185) serve a similar function to establish a reference for quantitative measurements.

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