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The Copalis™ TORC Total Antibody Assay uses Coupled Particle Light Scattering (Copalis™) technology in a microparticle agglutinationbased immunoassay for the qualitative detection of total antibodies (IgG and IgM) to Toxoplasma gondii, rubella and cytomegalovirus (CMV) in human serum using the CopalisTM One Immunoassay System. The presence of antibodies is indicative of current or prior infection with the suspected organism. The results of this assay on a single serum specimen are used to determine the patient's immune status for rubella and to determine the patient's immunological experience for Toxoplasma gondii and CMV. When evaluating properly paired sera, the results of this assay are used to demonstrate seroconversion as evidence of recent infection. Both specimens should be tested simultaneously (see Interpretation of Results). This assay has not been FDA cleared or approved for the screening of blood or plasma donors.

The Copalis TORC Total Antibody Assay is based on the principle of antibodydependent particle aggregation as detected by measurement of changes in light scattering. Due to the unique measuring system, a sample can be tested for antibodies to Toxoplasma gondii, rubella and CMV using a single reagent and obtain results for the individual antibodies. Sized latex microparticles coated with inactivated Toxoplasma gondii, rubella and CMV antigens aggregate in the presence of antibodies to these infectious agents. After 10 minutes of agitation, the levels of aggregation are determined by discrimination of particle sizes and measurement of the number of reacted and unreacted particles as they flow past a detector. Reactivity is assessed by the level of aggregation per particle size relative to a cutoff value. The Copalis TORC Total Antibody Assay detects the presence of both IgM and IgG antibodies. Two levels of controls are used to monitor proficiency.

Here's an analysis of the acceptance criteria and the study proving device performance, based on the provided text for the Copalis™ TORC Total Antibody Assay:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as distinct numerical targets in the provided text. However, the "Performance Data" section outlines the evaluated metrics and their results, which implicitly serve as the achieved performance benchmarks.

Detailed Study Information:

1. Sample size used for the test set and the data provenance:

   • Clinical Sample Testing: A total of 250 serum samples were tested.
   • POL Proficiency Study: A 14-member blinded proficiency panel was used. Each panel member was tested in triplicate (across three runs) by multiple operators.
   • Data Provenance: The clinical sample testing was conducted at Sienna Biotech laboratory. The POL Proficiency Study was conducted at 3 POL sites. The text does not specify the country of origin but implies a US context given the FDA submission. Both studies appear to be prospective as they were conducted to evaluate the performance of the new device.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Clinical Sample Testing: The ground truth for this study was established by comparing the Copalis TORC Total Antibody Assay to the corresponding Abbott IMx assays. These predicate devices are established assays, implying their results serve as the reference standard. The text does not specify the number or qualifications of experts involved in running the Abbott IMx assays or in interpreting their results for ground truth determination.
   • POL Proficiency Study: The "expected" results for the 14-member blinded proficiency panel were established by in-house testing on a comparator assay. Similar to the clinical sample testing, the text does not detail the number or qualifications of experts involved in establishing these "expected" results.

3. Adjudication method (e.g., 2+1, 3+1, none) for the test set:

   • The provided text does not describe an explicit adjudication method for resolving discordant results in either the clinical sample testing or the POL proficiency study. The ground truth was primarily established by comparator assays.

4. 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:

   • This document describes an immunoassay device, not an AI-powered diagnostic system. Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable to this device. The POL study did involve multiple operators (human users) to assess reproducibility and proficiency, but it was not framed as an AI-assist study.

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

   • The Copalis TORC Total Antibody Assay is a laboratory-based immunoassay system, not an algorithm that operates independently. Its performance data (sensitivity, specificity, reproducibility) are inherently "standalone" in the sense that they represent the device's analytical performance on samples, rather than human interpretation of device output. The "human-in-the-loop" aspect comes from laboratory personnel operating the system, not interpreting images or complex data in a way that AI would assist.

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

   • The ground truth for both the clinical sample testing and the POL proficiency study was established by results from comparator assays (Abbott IMx assays for clinical, and an unspecified "comparator assay" for the POL study's "expected" results). This falls under the category of reference standard testing using established diagnostic methods.

7. The sample size for the training set:

   • The provided document does not mention a training set. This is expected as the Copalis TORC Total Antibody Assay is an immunoassay, not a machine learning model that requires explicit training data. Its development would involve chemical and biological optimization, not algorithmic training.

8. How the ground truth for the training set was established:

   • Since there is no mention of a training set or machine learning components, the concept of establishing ground truth for a training set is not applicable to this device.

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