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The ADVIA Centaur Toxoplasma IgG assay is an IgG antibody capture microparticle direct chemiluminometric immunoassay for the quantitative or qualitative detection of IgG antibodies to the Toxoplasma gondii parasite in human serum qualitative EDTA, heparin) using the ADVIA Centaur System. The measurement of Toxoplasma IgG may be used to aid in the assessment of a patient's serological response from individuals including women of childbearing age. This assay may also be utilized with an IgM Toxoplasma result to determine recent serological response to Toxoplasma..

Testing should not be performed as a screening procedure for the general population.

This assay has not been cleared or approved by the FDA for the screening of blood or plasma donors.

Toxoplasma gondii is an intracellular parasitic protozoan that affects birds and mammals, with cats being the primary host. Infection is typically spread by eating raw or undercooked meat containing cysts or by coming in contact with oocyst-infected cat feces. Climate, dietary customs, and presence of cats influence the prevalence of T. gondii, which can vary considerably by geographical location and age. In healthy immunocompetent individuals, infections are usually asymptomatic or subclinical. If toxoplasmosis is diagnosed during the early stages of infection, the disease can be treated effectively with antibiotic therapy.

In pregnant women, T. gondii infection poses a potential threat to the fetus. The risk of a pregnant woman passing infection to the fetus is approximately 25% in the first trimester and increases to approximately 65% in the third trimester. The earlier in the pregnancy that the mother is infected the greater the potential severity of congenital toxoplasmosis. If the fetus becomes infected, the infant may have symptoms such as lymphadenopathy, chorioretinitis, microcephaly and cerebral calcifications. In immunosuppressed populations, such as cancer patients undergoing chemotherapy, transplants recipients, and AIDS patients, T. gondii has emerged as an important opportunistic pathogen leading to severe or fatal infections. The immunosuppressed state of these patients is thought to allow reactivation of a latent infection, and these patients may present symptoms such as headaches, confusion, fever, and focal neurological deficits.

Use of toxoplasma IgG assays has been shown to be a reliable method for establishing immune status and evaluating susceptibility to T. gondii infection. The presence of IgG antibodies that the individual has been infected with toxoplasma in the past, but the level of reactivity does not indicate how recently the infection occurred. In the majority of AIDS patients, the IgG response to primary T. gondii infection often lacks a significant rise in IgG titers.

The ADVIA Centaur Toxoplasma G assay is an immunoglobulin class-capture sandwich immunoassay using direct, chemiluminometric technology. The anti-human IgGFc monoclonal antibody is covalently coupled to paramagnetic particles in the Solid Phase. In the Lite Reagent, the purified T. gondii antigen is bound to an anti-p30 monoclonal labeled with acridinium ester. Antibody-antigen complexes will form if toxoplasma IgG is present in the sample.

A direct relationship exists between the amount of toxoplasma IgG activity present in the patient sample and the amount of relative light units (RLUs) detected by the system. A result of positive or negative is determined using a clinical cutoff value of 10 IU/mL.

The provided text describes the performance characteristics of the Bayer Diagnostics ADVIA Centaur Toxoplasma IgG assay. The acceptance criteria are implicitly derived from the reported performance metrics, particularly "Relative Sensitivity and Specificity" and "CDC Panel" results.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as target values in the document. However, based on the provided results and the context of a 510(k) submission for substantial equivalence, the reported performance values are what the manufacturer submitted as demonstrating sufficient accuracy relative to a predicate device and a reference panel. The table below uses the "Total" values from the "Relative Sensitivity, Specificity, and Agreement Before Resolution of Discordant Samples" section and the "CDC Panel" results as key performance indicators.

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

• Sample Size for Relative Performance: A total of 1804 samples were tested at three U.S. sites.
  • Sub-populations: Prenatal (N = 494), Asymptomatic blood donors (N = 418), Asymptomatic hospital patients (N = 806), and 86 patients with confirmed toxoplasma IgG positive status.
• Data Provenance: Fresh and frozen samples from the mid-Atlantic and Midwest regions of the United States. The study is retrospective as it uses collected samples.
• Sample Size for CDC Panel: The CDC panel consisted of 100 specimens (70 positive and 30 negative).
• Sample Size for Interfering Agents: 128 viral antibodies and disease state specimens.

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 or qualifications of experts used to establish the ground truth for the test set.

• For the "Relative Sensitivity and Specificity" study, the ground truth was based on a commercially available, automated toxoplasma IgG EIA (predicate device). Discordant results were further evaluated using "other commercially available tests for toxoplasma IgG" (referred to as "Consensus Testing").
• For the "CDC Panel," the ground truth was established by the Centers for Disease Control (CDC), with specimens defined as positive or negative by the Dye Test.

4. Adjudication method for the test set

• For the "Relative Sensitivity and Specificity" study: Initially, the ADVIA Centaur results were compared to a predicate EIA. For discordant results (32 specimens), a form of adjudication was performed using "another commercially available test for toxoplasma IgG" (referred to as "Consensus Testing"). The exact method (e.g., sequential testing, resolution by a third test) is not explicitly detailed with a specific "2+1" or "3+1" notation, but it implies a process of resolving discrepancies using an additional reference method.
• For the "CDC Panel": The CDC's pre-characterized results based on the Dye Test served as the gold standard, so no further adjudication of the ADVIA Centaur results against this panel was performed by the study.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study is for an in-vitro diagnostic device (immunoassay) and does not involve human readers interpreting images or data alongside an AI tool. Therefore, there is no effect size related to human reader improvement with or without AI assistance.

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

Yes, this entire study describes the standalone performance of the ADVIA Centaur Toxoplasma IgG assay (an immunoassay device). It operates without human interpretation in the loop beyond sample preparation and result collection. The assay directly provides a quantitative result (IU/mL) and a classification (positive, negative, equivocal) based on a clinical cutoff.

7. The type of ground truth used

• For the "Relative Sensitivity and Specificity" study: The primary ground truth was derived from results of a commercially available, automated toxoplasma IgG EIA (predicate device), supplemented by consensus testing using other commercial toxoplasma IgG tests for discordant samples. This is a form of expert consensus/reference method comparison.
• For the "CDC Panel": The ground truth was based on the Dye Test, which is a highly regarded reference method for Toxoplasma gondii antibody detection, and the panel was characterized by the CDC. This is essentially a gold standard/reference method ground truth.
• For the Interfering Agents study: The negative toxoplasma IgG status of the specimens was "verified using alternative EIAs." This also points to a reference method comparison.

8. The sample size for the training set

The document does not provide information on a training set sample size. This is typical for an immunoassay development and validation rather than a machine learning model. The device itself is an immunoassay, not an AI/ML algorithm that undergoes explicit "training" in the conventional sense. The "training" would be more akin to assay development, optimization, and establishment of calibration curves, which don't have a distinct "training set" in the same way an AI algorithm does.

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

As there is no explicit "training set" for an AI/ML algorithm, the concept of establishing ground truth for it is not applicable here. The assay's performance characteristics (e.g., cutoff values, dynamic range) are established through analytical validation and clinical correlation studies, typically against established reference methods or clinically defined patient populations, rather than an AI-specific training process. The standardization against the WHO 3rd International Standard for anti-Toxoplasma Immunoglobulin in human serum is a key aspect of defining the assay's quantitative output.

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