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The Access Toxo IgG assay is a paramagnetic-particle, chemiluminescent immunoassay for the qualitative and quantitative determination of IgG antibodies to Toxoplasma gondii in human serum using the Access Immunoassay Systems. The Access Toxo IgG assay aids in the diagnosis of Toxoplasma gondii infection and may be used to assess the immune status of pregnant women.

This product is not FDA cleared/approved for the screening of blood or plasma donors. Assay performance characteristics have not been established for immunocompromised or immunosuppressed patients, cord blood, neonatal specimens or infants.

The Access Toxo IgG assay is a paramagnetic-particle, chemiluminescent immunoassay for the qualitative and quantitative detection of Toxoplasma gondii-specific IgG antibody in adult human serum using the Access Immunoassay Systems.

The Access Toxo IgG assay consists of the reagent pack, calibrators, and quality controls (OCs), packaged separately. Other items needed to run the assay include substrate and wash buffer.

This document describes the premarket notification (510(k)) for the Beckman Coulter Access Toxo IgG assay, a chemiluminescent immunoassay for detecting IgG antibodies to Toxoplasma gondii in human serum. This product is intended to aid in the diagnosis of Toxoplasma gondii infection and assess the immune status of pregnant women.

The submission claims substantial equivalence to a legally marketed predicate device, the Access Toxo IgG assay (K080869). The primary difference highlighted is the instrument used: the new device runs on the DxI 9000 Access Immunoassay Analyzer, while the predicate runs on the Access 2 Immunoassay System.

Here's an analysis of the provided information, focusing on the study that proves the device meets the acceptance criteria:

1. Table of Acceptance Criteria and Reported Device Performance

Strictly speaking, the document does not present "acceptance criteria" in a separate table with yes/no compliance. Instead, it details specific performance metrics and their measured values. The implicit acceptance criterion for most analytical performance studies (like imprecision and method comparison) is that the new device's performance is acceptable for its intended use and comparable to or better than the predicate. For Linearity, LoB, LoD, and LoQ, the acceptance criterion is that the study supports the claimed values.

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

• Method Comparison:

  • Test Sample Size: 140 native serum samples.
  • Data Provenance: The document does not explicitly state the country of origin or whether the samples were retrospective or prospective. It refers to "native serum samples," which typically implies real-world patient samples.

• Imprecision (Within-Laboratory):

  • Test Sample Size: 6 serum samples (analyzed across 240 replicates each).
  • Data Provenance: Not specified for origin or prospective/retrospective.

• Imprecision (Reproducibility):

  • Test Sample Size: 6 serum samples (analyzed across 225 replicates each).
  • Data Provenance: Performed at an "internal site." Not specified for origin or prospective/retrospective.

• Linearity, LoB, LoD, LoQ: The type and number of samples used for these studies are not specified, only that "a study" was performed and values were "claimed."

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

This type of information (experts, qualifications) is primarily relevant for studies involving human interpretation or clinical diagnosis, such as imaging studies where radiologists establish ground truth.

For this in vitro diagnostic (IVD) device (an immunoassay), the "ground truth" for the test results is established by the measurement itself and comparison to a reference method or validated system (the predicate device). There are no human experts involved in interpreting the raw assay output to establish ground truth for method comparison or analytical performance studies like imprecision. The "truth" is the analytical measurement obtained by the reference method (the predicate device or a highly characterized sample).

4. Adjudication Method for the Test Set

Not applicable. As this is an IVD immunoassay, not a human reader study, adjudication methods (like 2+1 or 3+1 for imaging reads) are not relevant here. The comparison is between two analytical instruments/systems.

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

Not applicable. This device is an in vitro diagnostic immunoassay. It does not involve human readers interpreting images assisted by AI, nor is it an AI-driven device in the sense of image analysis. Its function is to quantitatively and qualitatively measure an analyte in a biological sample.

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

Yes, the primary studies listed (Method Comparison, Imprecision, Linearity, LoB, LoD, LoQ) are all "standalone" in the sense that they evaluate the analytical performance of the device itself (Access Toxo IgG assay on the DxI 9000 Access Immunoassay Analyzer) without human interpretation affecting the measurement outcome. The device's output is a quantitative (IU/mL) or qualitative (Reactive/Non-Reactive/Equivocal) result.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)

For the method comparison study, the "ground truth" was essentially the results obtained from the predicate device (Access Toxo IgG assay on the Access 2 Immunoassay System). The goal was to show that the new device on the new instrument produced comparable results to the already cleared predicate.

For the analytical performance studies (Imprecision, Linearity, LoB, LoD, LoQ), the "ground truth" refers to the inherent analytical properties of the assay and instrument, which are determined by testing characterized samples (e.g., known concentrations for linearity, low-concentration samples for LoD/LoB).

8. The Sample Size for the Training Set

This document does not provide information about a "training set" in the context of machine learning or AI models. For IVD assays, "training" typically refers to the development and optimization process that precedes validation studies. The analytical performance studies presented here are primarily validation studies.

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

Not applicable, as a "training set" in the context of AI/ML ground truth establishment is not relevant to this type of IVD device submission. Assay development and optimization for IVDs involve extensive R&D, but the concept of "ground truth for training" as seen in AI is not directly applicable to a chemical immunoassay.

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