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

Note:

• . Patient testing with the Platelia® Toxo IgM assay must be performed in conjunction with an anti-Toxoplasma gondii IgG antibody assay.
• The Platelia® Toxo IgM assay is presumptive for the detection of anti-● Toxoplasma gondii IgM antibodies and presumptive for the diagnosis of acute, recent or reactivated Toxoplasma gondii infection.
• The performance of the Platelia® Toxo IgM assay has not been established for ● neonate testing.
• . The Platelia® Toxo IgM assay has not been cleared/approved by the FDA for blood/plasma donor screening.

The Platelia® Toxo IgM TMB assay is a qualitative assay which utilizes an immunocnzymatic double sandwich method. Diluted samples and controls are placed into microplate wells coated with antibodies to human IgM. The IgM antibodies present in the samples are captured by the solid phase. Remaining antibodies (including any of the IgG class) and other serum proteins are removed by washing. A solution containing T. gondii antigen and conjugate (monoclonal antibody to T. gondii labeled with horseradish peroxidase) is placed into each well. T. gondii IgM antibodies in the test sample that are captured on the solid phase bind the T. gondii antigen-complex. Excess T. gondii antigen and conjugate are removed by washing. A peroxidase substrate and chromogen solution is added which reacts with the conjugate to initiate a color development reaction is stopped by the addition of an acid. The optical density readings for the test samples are obtained with a spectrophotometer set at a wavelength of 450 nm. The presence of T. gondii IgM antibodies in an individual sample is determined by comparing the optical density reading for the sample to the optical density reading of the cut-off control serum.

Here's an analysis of the provided text, focusing on the acceptance criteria and the study used to demonstrate the device meets those criteria:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the document. Instead, the document demonstrates substantial equivalence to a predicate device and provides performance metrics. Based on the comparison study, the implicit acceptance criteria would be very high agreement rates with a legally marketed predicate device.

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

• Comparison Studies:
  • Test Set Sample Size: 348 patient samples and 97 specimens from 40 seroconversion panels, for a combined total of 445 specimens.
  • Data Provenance: The document states that 445 fresh and frozen serum samples were "obtained from pregnant women during routine laboratory activities in the area of Paris, France." It also mentions "comparative prospective and retrospective testing" but does not specify the origin or nature of the "patient samples" portion of the 348. The 97 seroconversion panel specimens are not given specific provenance beyond being "from 40 seroconversion panels."
• CDC Test Panel:
  • Test Set Sample Size: 32 positive samples and 65 negative samples, for a total of 97 samples.
  • Data Provenance: "serum panel obtained from the CDC." (Country of origin implicitly USA).

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

The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test set. For the "Comparison Studies," the reference for ground truth is "another commercially available enzyme immunoassay (EIA)", which implies that its results were taken as the standard. For the "CDC Test Panel," the samples are described as "masked, characterized serum panel," suggesting they have a pre-established ground truth, likely determined by experts or a reference method, but no details are provided.

4. Adjudication Method for the Test Set

The document does not mention any adjudication method for the test set. The comparison is made directly against a predicate EIA device or pre-characterized CDC panels. There is no indication of multiple readers or an adjudication process for discrepancies.

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

No, an MRMC comparative effectiveness study was not done. This device is an in-vitro diagnostic assay, not an AI imaging device involving human readers.

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

Yes, the performance presented for the Platelia® Toxo IgM TMB assay is a standalone, algorithm-only performance. It refers to the kit's ability to detect antibodies based on optical density readings and comparison to a cut-off control, without human interpretation of ambiguous results (beyond following the kit's instructions for qualitative interpretation). The "Note" about physician interpretation in conjunction with an IgG assay refers to clinical utility, not the device's standalone analytical performance.

7. The Type of Ground Truth Used

• Comparison Studies: The ground truth for the comparison study was based on the results of "another commercially available enzyme immunoassay (EIA)"—specifically the Kallestad Diagnostics Platelia® Toxo IgM (K89498), which is the predicate device.
• CDC Test Panel: The ground truth for the CDC test panel was based on a "masked, characterized serum panel," implying that the positivity or negativity of these samples was previously established by authoritative methods or reference labs (likely expert-driven characterization).

8. The Sample Size for the Training Set

The document does not provide information on a "training set" in the context of an algorithm or machine learning model. This is an immunoassay kit, where the "training" equivalent would be the development and optimization of the assay itself based on various biological samples, but specific sample sizes for such development are not listed as a "training set."

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

As this is an immunoassay and not an AI/ML device, the concept of a "training set" with established ground truth, as typically understood in AI, does not directly apply. The design and optimization of the assay components (e.g., antigen, conjugate, chromogen) would have been based on extensive laboratory work and validation using known positive and negative samples, but these are not delineated as a formal "training set" with a separate ground truth establishment process in the context of this 510(k) summary.

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