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

The Access Toxo IgM II assay is presumptive for the diagnosis of acute, recent, or reactivated Toxoplasma gondii infection in males and pregnant females. It is recommended this assay be performed in conjunction with a Toxoplasma gondii-specific IgG antibody assay.

Note: This assay has not been cleared/approved by the FDA for the screening of blood or plasma donors in the United States.

The Access Toxo IgM II assay is a paramagnetic-particle chemiluminescent immunoassay for the qualitative detection of Toxoplasma gondii-specific IgM antibody in human serum and plasma using the Access Immunoassay Systems. The Access Toxo IgM II Calibrators are intended for use with the Access Toxo IgM II assay for the qualitative detection of Toxoplasma gondii-specific IgM antibody in adult human serum and plasma using the Access Immunoassay Systems. The Access Toxo IgM II QC is intended for monitoring system performance of the Access Toxo IgM II assay. The Access assay consists of the reagent pack, calibrators and QCs. Other items needed to run the assay include substrate and wash buffer. The Access assay reagent pack, Access assay callorators, Access QCs, along with the UniCel DxI Wash Buffer II are designed for use with the DxI 9000 Access Immunoassay Analyzer in a clinical laboratory setting.

The provided text is a 510(k) premarket notification summary for the Access Toxo IgM II assay, a diagnostic immunoassay, not an AI/ML-driven device. Therefore, many of the requested criteria (e.g., sample size for training set, number of experts for ground truth, MRMC study, AI assistance effect size) are not applicable to this type of medical device submission.

However, I can extract and present the relevant information regarding the device's acceptance criteria and the study proving it meets these criteria based on the provided text.

Acceptance Criteria and Device Performance for Access Toxo IgM II Assay

This document describes the validation of the Access Toxo IgM II assay on the DxI 9000 Access Immunoassay Analyzer, demonstrating its substantial equivalence to the previously cleared Access Toxo IgM II assay on the Access 2 Immunoassay System. The primary performance metrics reported are Positive Percent Agreement (PPA), Negative Percent Agreement (NPA), and Imprecision (CV%).

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the results presented, which showed 100% agreement for both positive and negative samples, and the imprecision results were well within the design specification.

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

• Method Comparison Study: 152 samples.
  • Data Provenance: Samples were "collected from the intended use population." The study was "performed at an internal site." No specific country of origin or whether the data was retrospective or prospective is mentioned, but "intended use population" generally implies clinical samples.
• Imprecision Studies (Within-Laboratory & Reproducibility):
  • For each of the 4 samples tested: N = 240 (for within-laboratory precision) and N = 225 (for reproducibility). These represent the number of individual measurements.
  • The study involved testing multiple samples in duplicate (for precision) or in replicates of 5 (for reproducibility) over multiple days, across three reagent/calibrator lots and three analyzers.

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

N/A. This is a laboratory diagnostic immunoassay, not an image-based AI/ML device where expert consensus for ground truth is typically required. The "ground truth" for the method comparison study was the result from the FDA-cleared predicate device (Access Toxo IgM II on the Access 2 Immunoassay System).

4. Adjudication Method for the Test Set

N/A. The comparison was directly between the candidate device (DxI 9000) and the predicate device (Access 2). There was no human adjudication process involved in settling discrepancies between results from different analyzers beyond standard laboratory procedures for confirming unexpected results.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC study was not done. This type of study is relevant for imaging devices or AI-assisted diagnostic tools where human reader performance is a key metric. This submission is for an automated immunoassay.

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

Yes, the studies evaluate the standalone performance of the device/assay system (Access Toxo IgM II on the DxI 9000) against a reference standard (predicate device or established precision metrics). The system itself performs the measurement and provides a qualitative (Reactive, Equivocal, Non-Reactive) result. There isn't an "algorithm only" in the AI/ML sense, but the device operates autonomously to produce results.

7. The Type of Ground Truth Used

• Method Comparison: The results obtained from the FDA-cleared predicate device (Access Toxo IgM II on the Access 2 Immunoassay System) served as the reference for determining agreement.
• Imprecision: The consistency of the device's own measurements provided the "ground truth" for precision relative to established statistical methods (CLSI EP05-A3).

8. The Sample Size for the Training Set

N/A. This is not an AI/ML device that requires a distinct "training set." The device is a chemical immunoassay system. The development of such assays involves extensive R&D, reagent formulation, and analytical validation, but not "training data" in the machine learning sense.

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

N/A. As stated above, there is no "training set" or corresponding ground truth establishment in the context of an AI/ML model. The assay's analytical performance relies on validated biochemical reactions and instrument calibration.

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The Alinity i Toxo IgM assay is a chemiluminescent microparticle immunoassay (CMIA) used for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum, serum separator, and plasma tubes (lithium heparin, lithium heparin separator, and tripotassium EDTA) on the Alinity i system.

The Alinity i Toxo IgM assay is to be used as an aid in the diagnosis of acute or recent Toxoplasma gondii infection in suspected individuals including women of child-bearing age. It is recommended that the assay be performed in conjunction with a Toxoplasma gondii IgG assay.

The Alinity i Toxo IgM assay has not been cleared for use in screening blood, plasma, or tissue donors.

The Alinity i Toxo IgM assay is an automated, two-step immunoassay for the qualitative detection of IgM antibodies to Toxoplasma gondii in human serum and plasma using chemiluminescent microparticle immunoassay (CMIA) technology. The kit includes Reagents (Microparticles and Conjugate), Calibrator, and Controls.

The provided text is a 510(k) Summary for the Abbott Laboratories Alinity i Toxo IgM assay. It details the device's characteristics, intended use, and performance studies to demonstrate substantial equivalence to a predicate device.

Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided document:

1. A table of acceptance criteria and the reported device performance

The document does not explicitly present a "table of acceptance criteria" with predefined thresholds that the device must meet in a comparative format. Instead, it presents various performance studies (precision, analytical specificity, cross-reactivity, matrix equivalency, class specificity, CDC panel agreement, and clinical agreement) and then summarizes the results of these studies. The implicit acceptance criteria are the successful demonstration of performance comparable to a cleared device and FDA guidance documents.

However, we can infer some "acceptance criteria" from the results presented, especially in the CDC Panel Agreement and Clinical Agreement sections. The document highlights the Percentage Positive Agreement (PPA) and Percentage Negative Agreement (NPA) as key metrics.

Here's a table focusing on the performance of the Alinity i Toxo IgM assay as tested against established benchmarks:

Table of Device Performance Metrics

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Cutoff Establishment (Internal Validation): 1219 samples (1053 nonreactive, 166 reactive). Data provenance not specified (likely internal laboratory samples, retrospective).
• Within-Laboratory Precision (20-Day): Not directly a "test set" sample size for diagnostic accuracy, but involves 2 controls and 4 plasma panels tested multiple times (360-360 replicates per control/panel).
• Analytical Specificity (Interference): Samples with target ranges of anti-Toxo IgM (0.60 to 0.99 S/CO and 1.00 to 2.00 S/CO) spiked with interferents. Specific number of samples per substance/condition not given, but refers to CLSI guidance.
• Cross-Reactivity: 177 serum specimens from individuals with other medical conditions and high titer Toxoplasmosis IgG. Data provenance not specified (likely retrospective or collected for study).
• Matrix Equivalency: 43 donors (20 reactive, 23 nonreactive). Samples collected in 5 different tube types. Data provenance not specified.
• Class Specificity: Not specified as a separate sample set size, likely inferred from internal controls or prepared samples.
• CDC Panel Agreement: 97 specimens (32 true positive, 65 true negative) from the CDC Toxoplasma 1998 Human Serum Panel. This is a retrospective, well-characterized panel.
• Reproducibility (5-Day, Multi-Site): Same sample panels as within-laboratory precision (controls and 4 plasma panels) tested across 3 US sites. 360 replicates per sample.
• Clinical Agreement:
  • Population 1: 897 consecutively collected remnant specimens. 169 from the US and 710 from outside the US. This implies a mixture of retrospective and potentially prospective collection depending on "consecutively collected remnant specimens."
  • Population 2: 207 consecutively collected remnant specimens from pregnant women in the US. This implies a mixture of retrospective and potentially prospective collection.
  • Total US specimens in the clinical study: 376 (169 from Pop 1 + 207 from Pop 2).

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

• The document does not mention the use of experts (e.g., radiologists) for establishing ground truth, as this is an in vitro diagnostic (IVD) device for serological testing.
• Ground Truth for IVDs: For IVDs like this, "ground truth" is typically established by:
  • Reference Method/Predicate Device: The clinical agreement study uses an "FDA-cleared, commercially available anti-Toxo IgM assay" (the bioMérieux VIDAS TOXO IgM assay) as the comparator, which serves as the reference standard for clinical performance.
  • Well-Characterized Panels: The CDC Toxoplasma 1998 Human Serum Panel is used, where the "true positive" and "true negative" status of specimens are established by the CDC through their own rigorous characterization processes.
  • Internal Characterization: For studies like cutoff determination, samples are "characterized with a commercially available anti-Toxo IgM assay," implying the use of an existing reference method.

Therefore, the "experts" in this context are the established reference methods and panels from organizations like the CDC, rather than individual human interpretative experts for modalities like radiology.

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

• Adjudication methods like 2+1 or 3+1 are typically used in imaging studies where multiple human readers interpret images, and discrepancies are resolved by an expert panel.
• For an IVD assay like this, the "adjudication" is inherent in the comparison to a predefined reference standard (the predicate device or the CDC panel's established status) or by the assay's internal cutoff determination process.
• The document does not describe any specific human "adjudication" process for the result of the Alinity i Toxo IgM assay beyond its comparison to the comparator assay or CDC panel.

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, an MRMC comparative effectiveness study was not done.
• MRMC studies are specific to AI/CADe (Computer-Assisted Detection) or CADx (Computer-Assisted Diagnosis) devices that assist human readers in interpreting medical images.
• The Alinity i Toxo IgM assay is an in vitro diagnostic (IVD) device that performs a laboratory test for antibodies; it does not involve human readers interpreting images or AI assistance for such interpretation.

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

• Yes, this device inherently performs as a standalone "algorithm" in the sense that it is an automated laboratory assay. The results (S/CO values) are generated by the instrument based on its chemical reactions and detection system, and then interpreted against predefined cutoffs.
• While a human operator loads samples and manages the instrument, the diagnostic detection (CMIA technology for Toxo IgM antibodies) is fully automated by the device itself, without human interpretation of the primary result (RLU or S/CO). The physician then interprets the qualitative result (Reactive, Grayzone, Nonreactive) in the context of the patient's clinical picture.
• The performance metrics (precision, analytical specificity, cross-reactivity, CDC panel agreement, clinical agreement) are all measures of this standalone analytical performance.

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

The ground truth for this device was established primarily through:

• Reference Standard/Predicate Assay: For the clinical agreement study, the Alinity i Toxo IgM assay results were compared against an FDA-cleared, commercially available anti-Toxo IgM assay (the bioMérieux VIDAS TOXO IgM assay). This predicate device serves as the clinical "ground truth" or reference.
• Well-Characterized Panel: For the CDC Panel Agreement study, the ground truth was the established status of samples within the CDC Toxoplasma 1998 Human Serum Panel (i.e., known true positive or true negative Toxoplasma specimens). This panel's characterization is highly reliable.
• Internal Characterization/Comparator Assay: For cutoff establishment, samples were characterized using a "commercially available anti-Toxo IgM assay."

8. The sample size for the training set

• The document does not explicitly describe a separate "training set" in the context of machine learning or AI model development.
• For IVD devices, a "training set" might loosely refer to the samples used during assay development and optimization (e.g., for reagent formulation, instrument parameters, and initial cutoff setting), but this data is not typically reported as a formalized "training set" size in the same way as for AI.
• The closest description of data used for internal calibration/optimization is the 1219 samples used for assay cutoff establishment (1053 anti-Toxo IgM nonreactive samples and 166 anti-Toxo IgM reactive samples). This dataset could be considered analogous to a development/training set for establishing the assay's interpretation rules, although it's crucial to understand this isn't an AI/ML context.

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

• As mentioned above, there isn't a traditional "training set" for an AI model.
• For the 1219 samples used to establish the assay cutoff, the ground truth (reactive/nonreactive) was established by characterizing these samples with a "commercially available anti-Toxo IgM assay." This means the existing, established methods of Toxo IgM detection were used to classify these samples, allowing the Alinity i assay to be "trained" (or its cutoff optimized) to align with those established classifications.

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The ARCHITECT Toxo IgG assay is a chemiluminescent microparticle immunoassay (CMIA) used for the quantitative determination of IgG antibodies to Toxoplasma gondii in human serum and plasma on the ARCHITECT i System.

The ARCHITECT Toxo IgG assay is to be used as an aid in the detection of immune status to Toxoplasma gondii in individuals, including women of child-bearing age, and as an aid in the diagnosis of Toxoplasma gondii infection.

Not intended for use in screening blood, plasma, or tissue donors.

The ARCHITECT Toxo IgG reagent kit contains:

• Microparticles: Recombinant Toxoplasma gondii antigen coated microparticles in MES buffer with protein (bovine). Minimum concentration: 0.03% solids. Preservative: ProClin 300.
• Conjugate: Murine acridinium-labeled anti-human IgG in MES buffer with protein (bovine) stabilizer. Minimum concentration: 0.05 µg/mL. Preservatives: antimicrobial agents.
• Assay Diluent: TRIS buffer with protein (murine) and protein (bovine). Preservative: ProClin 300.

The ARCHITECT Toxo IgG Calibrators:

• Calibrator A - an aqueous solution with protein (bovine) stabilizer. Preservative: ProClin 300.
• Calibrators B through F - contain anti-Toxo IgG in an aqueous solution with protein (bovine) stabilizer. Preservative: ProClin 300.

The ARCHITECT Toxo IgG Controls:

• Negative Control - contains recalcified human plasma with protein (ovine) stabilizer. Preservatives: ProClin 950 and sodium azide.
• Positive Control 1 - contains anti-Toxo IgG in aqueous solution with protein (bovine) stabilizer. Preservative: ProClin 300.

This assay is a two-step immunoassay for the quantitative determination of IgG antibodies to Toxoplasma gondii in human serum and plasma using chemiluminescent microparticle immunoassay (CMIA) technology.

The provided text describes the Abbott ARCHITECT Toxo IgG assay, a chemiluminescent microparticle immunoassay for the quantitative determination of IgG antibodies to Toxoplasma gondii. This document is a 510(k) premarket notification summary, which means it aims to demonstrate substantial equivalence to a legally marketed predicate device, not necessarily to prove its own absolute effectiveness against a clinical ground truth like disease outcome or pathology.

Therefore, the acceptance criteria are primarily demonstration of analytical performance that is substantially equivalent to the predicate device and supports the stated indications for use. The "study that proves the device meets the acceptance criteria" refers to the nonclinical and clinical laboratory studies presented in the 510(k) summary that support this substantial equivalence.

Here's an analysis of the requested information based on the provided text:

1. A table of acceptance criteria and the reported device performance

The document doesn't explicitly list "acceptance criteria" as a separate table. Instead, it presents performance data from various studies. The implicit acceptance criteria are the successful demonstration of performance characteristics typically required for an in vitro diagnostic device to be found substantially equivalent to a predicate.

Below is a table summarizing key performance metrics and the reported results. The "Acceptance Criteria" column reflects the generally expected performance for such assays or thresholds implicitly met by the reported data, rather than specific numerical targets stated in the document.

2. Sample size used for the test set and the data provenance (e.g., country of origin of the data, retrospective or prospective)

• Precision and Reproducibility Studies:
  • Within-Laboratory Precision: 120 replicates per panel/control (e.g., Positive Control 1 N=120, Panel 3 N=120). Data provenance implicitly laboratory-based from Abbott.
  • System Reproducibility: 360 replicates per control/panel (e.g., Positive Control 1 N=360). Conducted at 3 clinical sites (US based: New York City and Farmingdale, New York, and Palo Alto, California).
• Lower Limits of Measurement: N ≥ 60 replicates per analyte level. Data provenance implicitly laboratory-based from Abbott.
• Analytical Specificity:
  • Interfering Endogenous Substances, Drugs, and Other Substances: Not specified exact number of replicates per interferent, but tested at 2 analyte levels.
  • Potentially Interfering Other Conditions: 164 specimens.
• CDC Panel Agreement: 100 specimens (70 true positive, 30 true negative) from the CDC Toxoplasma 1998 Human Serum Panel (implies retrospective, pre-characterized samples).
• Percent Agreement (Method Comparison Clinical Study):
  • Total N = 1414 specimens.
  • Routine Order: 777 specimens (US) and 482 specimens (outside US). Total 1259.
  • Preselected Positive: 84 specimens (US) and 71 specimens (outside US). Total 155.
  • Pregnant Females: 200 specimens (US).
  • Data Provenance: The document explicitly states the clinical study was performed in the US (at 3 clinical testing sites located in New York City and Farmingdale, New York and Palo Alto, California) and with samples collected in the US and outside of the US. The study is described as a "clinical study," implying prospective collection and testing, but the use of "preselected positive" specimens indicates some retrospective sample selection.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g., radiologist with 10 years of experience)

The document does not specify the number or qualifications of experts used to establish the ground truth for the test sets.

• For the CDC Panel, the "gold standard" was the Dye Test. This test itself is highly specialized and would have been performed by experts at the CDC, but their specific qualifications are not detailed here. The panel itself is a "masked, characterized serum panel," implying its ground truth was established prior to this study.
• For the Percent Agreement (Method Comparison) study, the "ground truth" was established by a "current FDA cleared commercially available anti-Toxo IgG assay" (the comparator device). For discordant samples from this study, the Dye Test was used as a reference. Again, the experts performing these comparator or Dye Tests are not detailed.
• For the Precision, Linearity, and Analytical Specificity studies, the samples are either manufactured/spiked or are pre-screened based on other assays or clinical categories. The ground truth here is analytical rather than clinical, and is established by the methods of sample preparation and characterization typically done by laboratory scientists.

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

The document does not describe a formal reader (e.g., radiologist) adjudication method (like 2+1 or 3+1) because this is an in vitro diagnostic (IVD) assay, not an image-based AI device. The "reading" or determination of results is done by the automated ARCHITECT i System based on chemiluminescent reactions, not human interpretation of complex images.

For discordant results in the method comparison study, the Dye Test was used as an arbitration method for clarification. For example, in the routine order comparisons, 24 discordant samples were tested using the Dye Test.

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 MRMC comparative effectiveness study was done. This type of study (MRMC) is relevant for diagnostic imaging systems, particularly those that incorporate Artificial Intelligence (AI) to assist human readers (e.g., radiologists interpreting medical images).

The ARCHITECT Toxo IgG assay is an in vitro diagnostic immunoassay. Its "reader" is the ARCHITECT i System, an automated instrument. There is no human "reader" in the loop interpreting results in the same way a radiologist interprets an image. Therefore, questions about human reader improvement with AI assistance are not applicable to this device.

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

Yes, the performance of the ARCHITECT Toxo IgG assay is presented as standalone (algorithm/instrument only) performance. The ARCHITECT i System automatically processes samples and yields quantitative results (IU/mL) and qualitative interpretations (reactive, grayzone/equivocal, nonreactive). There is no "human-in-the-loop" affecting the primary measurement or interpretation by the device itself after it has been loaded.

The various precision, linearity, analytical specificity, and agreement studies (including the CDC panel agreement) demonstrate the standalone performance of the device.

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

The ground truth for evaluating this IVD device employed a combination of methods:

• Well-characterized Reference Panels: Specifically, the CDC Toxoplasma 1998 Human Serum Panel, which was characterized using the Dye Test (a highly regarded serological reference method for Toxoplasma IgG).
• Comparison to a Legally Marketed Predicate/Comparator Device: For the method comparison studies, the results of the ARCHITECT Toxo IgG assay were compared against a "current FDA cleared commercially available anti-Toxo IgG assay." This serves as a practical ground truth for demonstrating substantial equivalence within regulatory frameworks for IVDs.
• Arbitration with Reference Method: For discordant results in the method comparison study, the Dye Test was used as an arbitration method to resolve discrepancies and provide a more definitive "ground truth" for those specific samples.
• Analytical Ground Truth: For studies like linearity, precision, LoB/LoD/LLoQ, and analytical specificity, the "ground truth" is established by precisely prepared samples (e.g., known concentrations, spiked interferents, samples verified to be negative).

8. The sample size for the training set

The document describes premarket studies for a commercial IVD kit, not an AI/ML algorithm development. Therefore, there is no explicit "training set" in the context of machine learning model development.

The studies described are for validation and verification of the device's performance characteristics. For an IVD assay like this, the "training" aspect would relate to the assay's biochemical development, reagent formulation, and calibration curve generation, which are usually proprietary development processes and not "data sets" in the AI/ML sense.

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

As there is no explicit "training set" for an AI/ML model described for this IVD assay, this question is not directly applicable.

The development and internal optimization of an immunoassay typically involve extensive laboratory work where known standards and characterized samples are used to optimize reagent concentrations, reaction conditions, and calibration algorithms. The "ground truth" during such development would be based on reference methods, gravimetric/volumetric preparations, and established scientific principles of immunology and chemistry.

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The Elecsys Toxo IgM immunoassay is for the in vitro qualitative detection of IgM antibodies to Toxoplasma gondii in human serum and plasma. This assay may be used as an aid in the diagnosis of an acute or recent Toxoplasma gondii infection in suspected patients and pregnant women. Patient testing must be performed in conjunction with an anti-Toxoplasma gondii IgG antibody assay. The electrochemiluminescence immunoassay "ECLIA" is intended for use on Elecsys and cobas e immuno-assay analyzers. This assay has not been cleared by the FDA for blood/plasma donor screening.

PreciControl Toxo IgM is used for quality control of the Elecsys Toxo IgM immunoassay on the Elecsys and cobas e immunoassay analyzers.

The Elecsys Toxo IgM is a two-step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. In the first incubation 10 uL of sample are automatically prediluted 1:20 with Elecsys Diluent Universal and T. gondii-specific recombinant antigen labeled with a ruthenium complex is added. Anti-Toxo IgM antibodies present in the sample react with the ruthenium-labeled T. gondii-specific recombinant antigen. Then biotinylated monoclonal human-IgM- specific antibodies and streptavidin-coated microparticles are added. The complex becomes bound to the solid phase via interaction of biotin and streptayidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier. Results are determined automatically by the Elecsys software by comparing the electrochemiluminescence signal obtained from the reaction product of the sample with the signal of the cutoff value previously obtained by Toxo IgM calibration.

The provided document describes the Elecsys Toxo IgM Immunoassay, an in vitro qualitative test for the detection of IgM antibodies to Toxoplasma gondii. It details the performance evaluation supporting its substantial equivalence to a predicate device.

Here's an analysis of the acceptance criteria and study proving the device meets them:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for substantial equivalence are not explicitly listed in a table format with numerical targets, as might be seen for a novel device. Instead, the document presents performance metrics and compares them to a predicate device and established CLSI protocols. The implicit acceptance criterion is that the Elecsys Toxo IgM assay demonstrates comparable performance (precision, reproducibility, and agreement with a predicate method for clinical samples) to the legally marketed predicate device, VIDAS TOXO IgM Test System (K923166), for its stated indications for use.

Below is a table summarizing the reported device performance:

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

The "test set" in this context refers to the clinical samples used for performance evaluation against the predicate device.

• Study 1: 440 prospective specimens from a US reference laboratory.
• Study 2: 60 retrospective samples from a US commercial sample vendor.
• Study 3: 101 prospective samples from the general population in Europe. (87 of these were pregnant women).

Data Provenance:

• Country of Origin: US (Study 1 & 2), Europe (Study 3).
• Retrospective/Prospective: Mix of prospective (Studies 1 & 3) and retrospective (Study 2) samples.

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

The document does not specify the number or qualifications of experts used to establish the ground truth. The "ground truth" for the clinical performance studies (Studies 1, 2, and 3) was established by comparison with a "FDA cleared method," specifically the VIDAS TOXO IgM Test System (K923166), which served as the reference method. This indicates that the predicate device's results were considered the de-facto ground truth for the comparison.

4. Adjudication Method for the Test Set

The document does not describe an explicit adjudication method beyond comparing the Elecsys Toxo IgM results to those of the predicate device. It notes that "Equivocals are counted as discrepant results against the Elecsys." in the agreement calculations, implying a direct comparison without a multi-reader or independent adjudication process for discordant results.

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

This is an in vitro diagnostic (IVD) assay, not an AI-assisted diagnostic imaging device or a decision support system for human readers. Therefore, an MRMC comparative effectiveness study involving human readers with and without AI assistance is not applicable to this type of device. The study evaluates the performance of the assay itself.

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

Yes, the studies presented are essentially standalone performance evaluations of the Elecsys Toxo IgM immunoassay. It's an automated test run on Elecsys and cobas e immunoassay analyzers, with results determined automatically by its software. The performance data (precision, reproducibility, cross-reactivity, matrix equivalency, hook effect, and agreement with the predicate) are purely those of the assay system without human interpretation as part of the primary diagnostic step. Human involvement would be in sample collection and loading onto the analyzer, and clinical interpretation of the final report.

7. The Type of Ground Truth Used

The ground truth for the clinical performance evaluation was established by a predicate device/reference method: the VIDAS TOXO IgM Test System (K923166). In the context of IVD assays, this is a common and accepted form of "ground truth" for demonstrating substantial equivalence. It's not pathology, outcomes data, or expert consensus in the typical sense of a human panel reviewing images, but rather the result from another validated, cleared assay.

8. The Sample Size for the Training Set

The document does not provide information on a separate "training set" or its size for the Elecsys Toxo IgM immunoassay. For IVD assays like this, the "training" (or development/optimization) phase involves extensive analytical studies (e.g., reagent formulation, calibration curve development, cutoff determination, specificity, sensitivity studies during R&D) rather than machine learning on a distinct training dataset. The established "Assay Cut-off" was likely derived from a large set of characterized samples during the development phase.

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

Since there isn't an explicit "training set" described in the context of machine learning, the concept of establishing ground truth for it doesn't directly apply. However, the document states:

"The cut-off for the Elecsys Toxo IgM immunoassay was established by the use of sample collectives characterized with commercially available assays."

This indicates that the cutoff was determined based on a large collection of samples whose Toxoplasma gondii IgM status was characterized using other commercially available (presumably well-established reference or predicate) assays. This process is analogous to establishing ground truth for a development or training phase in IVD contexts. Specific details on the number of samples or the exact methodology of "characterization" are not provided but it implies a reference method was used.

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The BioPlex 2200 ToRC IgM kit is a multiplex flow immunoassay intended for the qualitative detection of IgM antibodies to Toxoplasma gondii), Rubella, and Cytomegalovirus (CMV) in human serum and plasma (K3 EDTA, lithium heparin, or sodium heparin).

The BioPlex 2200 ToRC IgM kit is intended for use with the Bio-Rad BioPlex 2200 System.

This kit is intended as an aid in the diagnosis of a current or recent T. gondii, Rubella and/or CMV infection, in individuals suspected of having one of the respective disease states, including women of child bearing age.

This assay is not FDA cleared or approved for use in testing (screening) blood or plasma donors.

Performance characteristics for the ToRC IgM assay have not been evaluated in immunosuppressed or organ transplant individuals. Performance characteristics of this kit have not been established for use in neonatal screening or for use at point of care facilities.

The BioPlex 2200 ToRC IgM Calibrator Set is intended for the BioPlex 2200 ToRC IgM Reagent Pack.

The BioPlex 2200 ToRC IgM Control Set is intended for use as an assayed quality control to monitor the overall performance of the BioPlex 2200 Instrument and BioPlex 2200 ToRC IgM Reagent Pack in the clinical laboratory.

BioPlex ToRC IgM Reagent Pack includes the following components:

• One (1) 10 mL vial, containing dyed beads coated with lysates of T. gondii, Rubella and CMV ● plus an Internal Standard bead (ISB) and a Serum Verification bead (SVB) in buffer with Glycerol and protein stabilizers (bovine and caprine). ProClin 300 (≤ 0.3%), sodium benzoate (≤ 0.1%) and sodium azide (< 0.1%) as preservatives.
• . One (1) 5 mL vial, containing phycoerythrin-conjugated murine monoclonal anti-human IgM antibody and phycoerythrin-conjugated murine monoclonal anti-human FXIII antibody, in buffer with protein stabilizers (bovine and murine). ProClin 300 (≤ 0.3%), sodium benzoate (≤ 0.1%) and sodium azide (< 0.1%) as preservatives.
• One (1) 10 mL vial, containing goat anti-human IgG antibody and protein stabilizers (bovine . and murine) in buffer. ProClin 300 (< 0.3%), sodium benzoate (< 0.1%) and sodium azide (< 0.1%) as preservatives.

BioPlex 2200 ToRC IgM Calibrator set contains two (2) 0.5 mL vials. The calibrators are provided in a human serum matrix made from defibrinated plasma with added known analyte concentrations consisting of HuCAL® recombinant IgM antibodies for rubella and human disease state plasma derived antibodies for T. gondii and CMV. All calibrators contain ProClin 300 (≤ 0.3%), sodium benzoate (≤ 0.1%) and sodium azide (< 0.1%) as preservatives.

BioPlex 2200 ToRC IgM Control set contains two (2) 1.5 mL Positive Control serum vials, containing human disease state plasma derived IgM antibodies to T. gondii and CMV, and HuCAL® recombinant IgM antibodies to Rubella in a human serum matrix made from defibrinated plasma; and two (2) 1.5 mL Negative Control serum vials, in a human serum matrix made from defibrinted plasma. All controls contain Amikacin (0.003%), Cycloheximide (C15H23NO4) (0.009%), Amphotericin B (0.002%), Cefotaxime Sodium (0.002%), Ciprofloxacin (0.005%), ProClin 300 (≤ 0.3%), sodium benzoate (≤ 0.1%) and sodium azide (< 0.1%).

Additional materials required but not supplied include BioPlex 2200 Sheath Fluid containing Phosphate Buffered Saline (PBS), ProClin 300 (0.03%) and sodium azide (<0.1%) as preservatives; and BioPlex 2200 Wash Solution containing Phosphate Buffered Saline (PBS) and Tween 20, ProClin 300 (0.03%) and sodium azide (<0.1%) as preservatives.

Here's an analysis of the provided text to extract information about the acceptance criteria and the study proving the device's performance, as requested.

The provided text describes the performance characteristics of the BioPlex 2200 ToRC IgM kit, which is a multiplex flow immunoassay for detecting IgM antibodies to Toxoplasma gondii, Rubella, and Cytomegalovirus (CMV).

Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as a section titled "Acceptance Criteria" with pass/fail metrics. Instead, the document presents various analytical and clinical performance studies, and the results of these studies implicitly represent the device's acceptable performance. For the purpose of this response, I will infer the acceptance criteria from the reported performance, particularly where quantitative results are presented.

1. Table of Acceptance Criteria and Reported Device Performance

Precision Data Tables (as presented in the document):

BioPlex 2200 Toxo IgM – CLSI EP5-A3 Precision

BioPlex 2200 Rubella IgM – CLSI EP5-A3 Precision

BioPlex 2200 CMV IgM – CLSI EP5-A3 Precision

Reproducibility Data Tables (across 3 sites):

BioPlex 2200 Toxo IgM - CLSI EP15-A3 Reproducibility

BioPlex 2200 Rubella IgM - CLSI EP15-A3 Reproducibility

BioPlex 2200 CMV IgM - CLSI EP15-A3 Reproducibility

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

• Precision/Reproducibility:
  • CLSI EP5-A3 Precision: 80 data points per panel member for each analyte (T. gondii, Rubella, CMV) and each sample matrix (Serum, Potassium EDTA, Sodium Heparin, Lithium Heparin). This means 80 samples per specific condition.
  • CLSI EP15-A3 Reproducibility: 120 replicates per panel member (4 replicates x 2 runs x 5 days x 3 sites). There were 6 panel members for each analyte. This equates to 720 samples per analyte across three sites for reproducibility.
• Cross-Reactivity: At least 10 specimens per potential cross-reactant for each of the three antibody assays.
• Matrix Comparison: A minimum of 40 sets of paired serum and plasma samples per analyte (N=51 to 60 for each analyte and matrix comparison).
• Method Comparison (Prospective):
  • 2129 prospective samples in total.
  • ~700 samples per analyte (T. gondii, Rubella, CMV).
  • 200 pregnant women samples for each analyte.
  • Data Provenance: Samples were submitted for T. gondii, Rubella, or CMV testing. These were prospective samples collected at 3 U.S. clinical testing sites.
• Method Comparison (Retrospective):
  • 210 T. gondii IgM presumptive positive samples (134 female, 76 male).
  • 101 Rubella IgM presumptive positive samples (44 female, 57 male).
  • 213 CMV IgM presumptive positive samples (119 female, 94 male).
  • Data Provenance: Presumed positive banked samples for ToRC IgM. Retrospective.
• Correlation with CDC Evaluation Panels: 97 samples for T. gondii IgM (CDC Panel). Data provenance from CDC.
• Seroconversion Testing: Commercially available seroconversion panels for T. gondii, Rubella, and CMV IgM.
• IgM Specificity: 10 samples for each analyte (T. gondii, Rubella, CMV).

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

The document does not explicitly mention "experts" in the context of establishing ground truth for the test set. Instead, for clinical performance, the ground truth for comparative studies was established by:

• Results from commercially available predicate T. gondii, Rubella, and CMV IgM assays.
• In cases of discrepancy, another FDA-cleared device was used for confirmation (e.g., for CMV IgM method comparison).
• For the CDC panel, the CDC's characterization of the samples served as the ground truth.

This implies that the "ground truth" relies on the established performance and regulatory clearance of existing in vitro diagnostic devices and reference panels, rather than expert human interpretation in the way it might for imaging studies. Healthcare professionals running these predicate assays are implied to be qualified clinical laboratory personnel, but no specific number or qualification of individual experts is provided as is typical for AI/imaging ground truth studies.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method in the context of human readers reviewing results. For the comparative studies, discrepancies between the new device and the predicate device were investigated using another FDA-cleared device to confirm serological status. This serves as a form of adjudication by a third, independent, and validated method.

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. This is an in vitro diagnostic (IVD) device, not an AI for human-in-the-loop performance improvement study. The performance is assessed based on direct assay results (qualitative detection of antibodies), not on human reader performance. Therefore, an MRMC study or calculation of human reader improvement with AI assistance is not applicable and was not performed.

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

Yes. The entire performance evaluation for the BioPlex 2200 ToRC IgM kit is effectively a "standalone" assessment of the device's ability to qualitatively detect IgM antibodies. The device generates an Antibody Index (AI) result, which is then interpreted against a defined cut-off (e.g., >1.1 AI for positive, <0.9 AI for negative, 0.9-1.1 AI for equivocal). This is an algorithm-only performance in the context of an IVD, as it directly measures analytes in a sample.

7. The Type of Ground Truth Used

The primary ground truth used for method comparison studies was:

• Results from established, commercially available, and presumably FDA-cleared predicate IVD devices.
• For specific discrepant results, another FDA-cleared device was used, implying a reliance on a higher standard or independent confirmation through a validated method.
• For T. gondii IgM, CDC reference sera panels were used, representing a type of reference standard/outcome data (serological status defined by reference lab/panel).
• Seroconversion panels represent samples with known disease progression/antibody development over time, establishing dynamic ground truth.
• DTT treatment for IgM specificity provides experimental evidence that the signal is specifically from IgM antibodies, using a chemical method to selectively inactivate IgM.

8. The Sample Size for the Training Set

The document does not explicitly describe a "training set" in the context of machine learning or AI. This is a traditional IVD device, and its performance is established through calibration and validation studies, not by training a machine learning model on a dataset.

However, the "Assay cut-off" section mentions: "A final cut-off of 1.0 AI was established for the BioPlex 2200 ToRC IgM assay based on an evaluation of 401, 454 and 511 test ordered and retrospective samples for T. gondii, Rubella and CMV IgM, respectively, of which the serological status was determined from the predicate T. gondii, Rubella and CMV IgM assays."

This set of samples, used for cut-off optimization, somewhat resembles a "development set" or "tuning set" in machine learning, though it's integral to the assay's design and calibration rather than a separate training phase.

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

As noted in point 8, there isn't a "training set" in the AI/ML sense. For the samples used to establish the assay cut-off, the serological status (ground truth) was determined from the predicate T. gondii, Rubella, and CMV IgM assays. This indicates that commercially available and validated assays were used to define the true positive/negative status of these samples for optimizing the new device's cut-off.

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The ADVIA Centaur Toxoplasma M (Toxo M) assay is an IgM antibody capture microparticle direct chemiluminometric in vitro diagnostic immunoassay intended for the qualitative detection of IgM antibodies to Toxoplasma gondii in serum or plasma (EDTA, heparin) using the ADVIA Centaur and ADVIA Centaur XP systems.

The ADVIA Centaur Toxo M assay is used to measure IgM antibody against T. gondii which is presumptive of an acute, recent, or reactivated toxoplasma infection. Any measurement of IgM antibody to T. gondii must be performed in conjunction with the determination of IgG antibody to T. gondii.

The ADVIA Centaur Toxo M assay is an immunoqlobulin class-capture sandwich immunoassay using direct, chemiluminometric technology. The anti-human IgM monoclonal antibody is covalently coupled to paramagnetic particles in the Solid Phase. In the Lite Reagent, the T. gondii antigen is complexed with an anti-p30 monoclonal antibody (F(ab)> fragment) labeled with acridinium ester. Antibody-antigen complexes will form if toxoplasma IgM is present in the sample.

The provided document describes a 510(k) premarket notification for a modified in vitro diagnostic immunoassay, the ADVIA Centaur Toxoplasma M (Toxo M) assay. The purpose of the submission is to demonstrate that the modified device is substantially equivalent to a legally marketed predicate device.

Here's an analysis of the acceptance criteria and the study proving the device meets them, based on the provided text:

Acceptance Criteria and Reported Device Performance

The document states that the purpose of the submission is to describe changes to the ADVIA Centaur Toxoplasma M (Toxo M) assay (K010755) and that the performance characteristics of the modified assay (precision, interference, and panel/patient sample testing) were evaluated and found comparable to those established for the previous version of the device (currently-marketed predicate).

The "Performance Characteristics" section in Table 2 (Similarities) lists the following for both the Predicate and Modified Device:

The overall conclusion states: "The results of performance testing and verification activities demonstrate that the design modifications to the ADVIA Centaur Toxo M assay do not impact its safety or effectiveness and do not alter its performance claims or alter its intended use, as described in the labeling. Based on the results of comparative testing, the modified ADVIA Centaur Toxo M assay is substantially equivalent in principle and performance to the currently-marketed predicate device, ADVIA Centaur Toxo M, cleared under 510(k) K010755."

This implies that the modified device met the same performance metrics as the predicate, which serves as the acceptance criteria.

Study Details and Data Provenance

The document describes "performance testing and verification activities" and "comparative testing" against the predicate device.

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

• The document does not explicitly state the specific sample sizes used for the test set in the analytical performance and panel/patient sample testing. It mentions "testing with panel samples and patient samples."
• Data Provenance: The document does not specify the country of origin for the data. It also does not explicitly state whether the studies were retrospective or prospective, though "performance testing and verification activities" would typically involve prospective testing with samples.

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

• This information is not provided in the document. The device is an in vitro diagnostic immunoassay, and its performance is typically assessed against a known standard or reference method, rather than expert clinical interpretation of images. The ground truth for this type of test generally comes from well-characterized reference panels or clinically confirmed diagnoses.

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

• Adjudication methods like 2+1 or 3+1 are typically used for subjective assessments, such as image interpretation by radiologists. For an objective immunoassay, an "adjudication method" in this sense is not applicable. The outcome is a quantitative measurement translated into a qualitative result (reactive/nonreactive) based on a defined cutoff.

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 is an in vitro diagnostic immunoassay, not an AI-assisted diagnostic imaging device that involves "human readers." Therefore, an MRMC comparative effectiveness study is not applicable and was not performed.

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

• This is an immunoassay device, which by its nature operates "standalone" in that it provides a result (reactive/nonreactive) based on its chemical and detection processes. While a human operates the instrument and interprets the final qualitative result (Index Value to reactive/nonreactive), the core measurement is a direct output of the algorithm/instrument. The device itself is the "standalone" entity.

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

• The document mentions "panel samples" and "patient samples." For an immunoassay detecting antibodies, the ground truth would typically be established by:
  • Reference laboratory testing using a gold standard method.
  • Clinical diagnosis based on a combination of patient symptoms, additional laboratory tests, and clinical follow-up.
  • Well-characterized control panels with known positive and negative status for T. gondii IgM antibodies.
• The document does not explicitly state which specific type/combination was used, but it would not be expert consensus in the sense of subjective interpretation, nor pathology in the tissue sense, but rather definitive lab results or clinical outcomes.

7. The sample size for the training set:

• This is a 510(k) submission for a modified immunoassay, not a machine learning or AI device that typically involves a distinct "training set." The development of the assay's cutoff values and optimization would have involved internal development processes, akin to "training," but the document does not specify a numerical sample size for this developmental phase.

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

• Similar to the testing set, the ground truth for the development/optimization of the immunoassay would have been established through well-characterized samples, reference methods, or clinically confirmed cases. As it's not an AI model, the concept of "ground truth for training set" in the context of supervised learning does not directly apply in the same manner. The establishment of reagent formulations and reaction parameters is based on biochemical principles and empirical optimization using characterized samples.

In summary, the provided document focuses on demonstrating substantial equivalence of a modified immunoassay by showing its performance is comparable to the predicate device, especially in terms of positive and negative percent agreement. Many of the questions regarding MRMC studies, expert adjudication, and distinct training/test sets are more relevant to AI/ML or imaging devices than to the described immunoassay.

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For VIDAS H. pylori IgG:
VIDAS® H. pylori IgG (HPY) is an automated qualitative test for use on the instruments of the VIDAS family, for the detection of anti-Helicobacter pylori IgG antibodies in human serum or plasma (EDTA) using the ELFA technique (Enzyme Linked Fluorescent Assay). The VIDAS HPY assay is intended as an aid in diagnosis of H. pylori infection in an adult symptomatic population.
This device is an in vitro diagnostic medical device for professional use only.

For VIDAS 3:
The VIDAS 3 system is a complete standalone immunodiagnostic system intended for trained and qualified laboratory technicians (daily routine use) and laboratory administrators (application configuration). This device is an in vitro diagnostic medical device for professional use only.

For VIDAS Lyme IgG II:
The VIDAS Lyme IgG II (LYG) assay is an automated qualitative enzyme immunoassay intended for use on the instruments of the VIDAS family in the presumptive detection of human IgG antibodies to Borrelia burgdorferi in human serum (plain or separation gel) or plasma (sodium heparin). It should be used to test patients with a history and/or symptoms of infection with B. burgdorferi. All VIDAS Lyme IgG II positive specimens should be further tested with a Western Blot IgG assay to obtain supportive evidence of infection with B. burgdorfei. This device is an in vitro diagnostic medical device for professional use only.

For VIDAS RUB IgG:
The VIDAS® RUB IgG (RBG) assay uses Enzyme Linked Fluorescent Assay (ELFA) technology on the instruments of the VIDAS family for the in vitro quantitative measurement of IgG antibodies to rubella virus in human serum. The VIDAS RUB IgG (RBG) assay is intended as an aid in the determination of immune status to rubella. The performance of this device has not been established for screening of cord blood, or for neonatal samples. Likewise, performance characteristics of the assay have not been established for immunocompromised or immunosuppressed individuals.
This device is an in vitro diagnostic medical device for professional use only.

For VIDAS TOXO IgM:
The VIDAS® TOXO IgM (TXM) assay is intended for use on the instruments of the VIDAS family (VITEK ImmunoDiagnostic Assay System) as an automated enzyme-linked fluorescent immunoassay (ELF A) for the presumptive qualitative detection of anti-Toxoplasma gondii IgM antibodies in human serum, as an aid in the diagnosis of acute, recent, or reactivated Toxoplasma gondii infection. This assay must be performed in conjunction with an anti-Toxoplasma gondii lgG antibody assay. VIDAS TOXO IgM (TXM) assay performance has not been established for prenatal screening or newborn testing. This assay has not been cleared by the FDA for blood/plasma donor screening. This device is an in vitro diagnostic medical device for professional use only.

For VIDAS Human Chorionic Gonadotropin:
The VIDAS® HCG (HCG) assay is intended for use on the instruments of the VIDAS family as an automated quantitative enzyme linked fluorescent immunoassay (ELFA) for the determination of human Chorionic Gonadotropin (hCG) concentration in human serum or plasma. The VIDAS HCG (HCG) assay is intended to aid in the early detection of pregnancy.
This device is an in vitro diagnostic medical device for professional use only.

For VIDAS T4:
The VIDAS® T4 (T4) assay is intended for use on the instruments of the VIDAS family as an automated quantitative enzyme-linked fluorescent immunoassay for the determination of human thyroxine (T4) concentration in serum or plasma (heparin). It is intended for use as an aid in the diagnosis and treatment of thyroid disorders. This device is an in vitro diagnostic medical device for professional use only.

For VIDAS Testosterone:
The VIDAS Testosterone (TES) assay is an automated quantitative test for use on the instruments of the VIDAS family for the enzyme immunoassay measure of total testosterone in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). It is intended as an aid in the diagnosis and management of conditions involving excess or deficiency of this androgen.
This device is an in vitro diagnostic medical device for professional use only.

For VIDAS TSH:
The VIDAS® TSH (TSH) assay is intended for use on the instruments of the VIDAS family as an automated quantitative enzyne-linked fluorescent immunoassay (ELFA) for the determination of human thyroid stimulating hormone- (TSH) concentration in human serum or plasma (heparin). It is intended for use as an aid in the diagnosis of thyroid or pituitary disorders.
This device is an in vitro diagnostic medical device for professional use only.

For VIDAS D-Dimer Exclusion II:
VIDAS® D-Dimer Exclusion II™ is an automated quantitative test for use on the instruments of the VIDAS family for the immunoenzymatic determination of fibrin degradation products (FbDP) in human plasma (sodium citrate, CTAD) using the ELFA technique (Enzyme Linked Fluorescent Assay).
VIDAS D-Dimer Exclusion II is indicated for use in conjunction with a clinical pretest probability assessment model to exclude deep vein thrombosis (DVT) and pulmonary embolism (PE) disease in outpatients suspected of DVT or PE. This device is an in vitro diagnostic medical device for professional use only.

The VIDAS® 3 instrument is an automated multiparametric immunoassay system, which uses ELFA (Enzyme Linked Fluorescent Assay) technology. The VIDAS 3 system offers primary tube sampling, automated sample dilution, reagent/sample detection and reagent traceability.
The technology used, which is adaptable to a wide range of assays, combines the EIA method with a final fluorescence reading: this technology is known as ELFA (Enzyme Linked Fluorescent Assay). The enzyme used in the VIDAS product range is alkaline phosphatase, which catalyzes the hydrolysis of the substrate 4-methyl umbelliferyl phosphate (4-MUP) into a fluorescent product 4-methyl umbelliferone (4-MU) the fluorescence of which is measured at 450nm. The immunological methods are either indirect ElA, immunocapture, sandwich or competition, all involving a conjugate using the alkaline phosphatase.

This document describes the performance data for several VIDAS assays when used on the VIDAS 3 instrument, comparing them to their performance on the predicate VIDAS instrument. The tests are primarily for establishing substantial equivalence for the new VIDAS 3 instrument and do not typically include detailed acceptance criteria for the assays themselves, which are already established for the predicate devices. The studies focus on method comparison, precision, linearity, and detection limits.

Here's a breakdown of the requested information based on the provided text, focusing on the VIDAS H. pylori IgG assay as a primary example, and generalizing for others where appropriate:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state acceptance criteria in a quantitative format for method comparison. Instead, it demonstrates "correlation" and "equivalency" between the new device (VIDAS 3) and the predicate device (VIDAS). For precision, specific CV% ranges are reported.

Here's an example for the VIDAS H. pylori IgG assay's method comparison:

Note: For quantitative assays like VIDAS RUB IgG, VIDAS HCG, VIDAS T4, VIDAS Testosterone, VIDAS TSH, and VIDAS D-Dimer Exclusion II, method comparison relies on slope, intercept, and correlation coefficient, implying acceptance criteria for these values (e.g., slope close to 1, intercept close to 0, high correlation coefficient). Precision for these assays also includes CV% for various components.

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

• VIDAS H. pylori IgG:

  • Test Set Size: 250 serum samples (positive, equivocal, and negative).
  • Data Provenance: Not explicitly stated (e.g., country of origin, retrospective/prospective). The study compares performance between two instruments, implying samples are run on both.

• VIDAS Lyme IgG II:

  • Test Set Size: 220 serum samples (positive and negative).
  • Data Provenance: Not explicitly stated.

• VIDAS RUB IgG:

  • Test Set Size (Quantitative Method Comparison): 112 serum samples (ranging from 0 to 225 IU/mL).
  • Test Set Size (Qualitative Method Comparison): 220 serum samples (positive, equivocal, and negative).
  • Test Set Size (CDC Reference Panel): 100 specimens (50 pairs of sera).
  • Data Provenance: Not explicitly stated for general samples. The CDC panel implies a curated and standardized set.

• VIDAS TOXO IgM:

  • Test Set Size: 198 serum samples.
  • Data Provenance: Not explicitly stated.

• VIDAS Human Chorionic Gonadotropin (hCG):

  • Test Set Size: 113 serum samples.
  • Data Provenance: Not explicitly stated.

• VIDAS T4:

  • Test Set Size: 105 serum samples.
  • Data Provenance: Not explicitly stated.

• VIDAS Testosterone:

  • Test Set Size: 172 serum samples.
  • Data Provenance: Not explicitly stated.

• VIDAS TSH:

  • Test Set Size: 179 serum samples.
  • Data Provenance: Not explicitly stated.

• VIDAS D-Dimer Exclusion II:

  • Test Set Size: 219 plasma samples.
  • Data Provenance: Not explicitly stated.

Across all assays, the studies are described as "Method Comparison" and "Precision" studies, which are typically retrospective analyses of patient samples to compare device performance to an established method.

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

This information is not provided in the document. For in vitro diagnostic devices, ground truth is typically established by comparative methods (e.g., predicate device, reference methods, clinical diagnosis, or other laboratory gold standards) rather than expert consensus on individual cases. The document states that performance was evaluated against the predicate device (e.g., "VIDAS H. pylori IgG assay on the VIDAS 3 to the VIDAS H. pylori IgG assay on the VIDAS"). The "ground truth" for these studies is the result obtained from the predicate VIDAS instrument using its established methodology.

For the VIDAS RUB IgG, a "CDC reference panel" and "CDC low-titer rubella antibody standard" are mentioned, where the reference panel sera were "titered by Hemagglutination Inhibition." This implies that the ground truth for this specific part of the study was established by a recognized reference method (Hemagglutination Inhibition) and certified reference materials from the CDC.

4. Adjudication Method for the Test Set

This information is not explicitly provided. For method comparison studies, typically, discordant results between the new device and the predicate device (or reference method) are investigated. However, the exact adjudication process (e.g., by a third, more definitive test, or expert review of patient clinical history) is not detailed. The phrase "results were evaluated according to CLSI EP12-A2" or CLSI EP9 suggests standard statistical methods for agreement or correlation, which do not necessarily involve expert adjudication of individual discrepancies beyond reporting them.

For quantitative assays where method comparison statistics (slope, intercept, correlation coefficient) are used, "outliers" were removed in some cases (e.g., VIDAS RUB IgG quantitative comparison), implying some form of review or statistical exclusion, but not necessarily expert "adjudication" in the sense of clinical decision-making.

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

No. This document describes performance studies for in vitro diagnostic instruments and assays, not imaging or similar devices that would typically involve human readers interpreting results. Therefore, an MRMC comparative effectiveness study, which assesses improvements in human interpretation with AI assistance, is not applicable and was not performed.

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

The studies described are for the standalone in vitro diagnostic instruments and their associated assays. These are standalone tests, meaning the algorithm (or assay chemistry in this case) processes the sample and provides a result without direct human interpretation of raw data for diagnosis. The "human-in-the-loop" here refers to trained laboratory technicians operating the instrument and interpreting the final quantitative or qualitative results according to established cut-offs/guidelines, rather than interpreting complex images or signals. The purpose of these studies is to confirm that the new instrument (VIDAS 3) produces equivalent results to the predicate instrument (VIDAS) for these assays.

7. The Type of Ground Truth Used

The primary type of "ground truth" used in these studies is the results obtained from the predicate device (VIDAS instrument) for the same assays. The goal is to demonstrate "substantial equivalence" of the new instrument (VIDAS 3) to the predicate.

For the VIDAS RUB IgG assay, a CDC reference panel where samples were "titered by Hemagglutination Inhibition" served as an additional, external reference for ground truth in a specific subset of testing. This is a form of reference method/standardized panel data.

8. The Sample Size for the Training Set

This information is not explicitly provided in the document. For in vitro diagnostic assays, "training sets" are usually involved in the initial development and optimization of the assay itself (e.g., establishing reagents, parameters, cut-offs). The studies described in this document are focused on the validation and verification of the new instrument's performance with existing, already developed assays, often referred to as "test sets" or "evaluation sets." The assays themselves were presumably developed and "trained" using various sample sets prior to these studies.

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

Since information on a distinct "training set" for the new instrument's validation isn't provided (as the assays were pre-existing), details on its ground truth establishment are also not available in this document. For the development of the original assays, ground truth would have been established through a combination of clinical diagnoses, established reference methods, and correlation with disease status.

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The LIAISON® Toxo IgG II assay uses chemiluminescent immunoassay (CLIA) technology on the LIAISON® XL Analyzer for the qualitative determination of specific IgG antibodies to Toxoplasma gondii in human serum. The results of this assay can be used as an aid in the assessment of the patient's serological status to infection with Toxoplasma gondii and in the determination of immune status of individuals including pregnant women. This assay has not been cleared/approved by the FDA for blood/plasma donor screening. U.S. Federal Law restricts this device to sale by or on the order of a physician.

Assay performance characteristics have not been established for immunocompromised or immunosuppressed patients, cord blood, neonatal specimens, or infants.

The LIAISON® Control Toxo IgG II (negative and positive) is intended for use as assayed quality control samples to monitor the performance of the LIAISON® Toxo IgG II assay on the LIAISON® XL Analyzer.

The method for qualitative determination of IgG antibodies to Toxoplasma gondii (anti-Toxo IgG) is an indirect chemiluminescence immunoassay (CLIA). The principal components of the test are magnetic particles (solid phase) coated with Toxoplasma gondii and a conjugate of mouse monoclonal antibodies to human IgG linked to an isoluminol derivative (isoluminol-antibody conjugate). During the first incubation, Toxoplasma gondii antibodies present in diluted calibrators, samples or controls bind to the solid phase. During the second incubation, the monoclonal antibody conjuqate reacts with anti-Toxo IgG that is already bound to the solid phase. After each incubation, unbound material is removed with a wash cycle. Subsequently, the starter reagents are added and a flash chemiluminescence reaction is thus induced. The light signal, and therefore, the amount of isoluminol-antibody conjugate, is measured by a photomultiplier as relative light units (RLU) and is indicative of the presence of anti-Toxo IqG in calibrators, samples or controls.

All assay steps and incubations are performed by the LIAISON® XL Analyzer.

The DiaSorin LIAISON® Toxo IgG II assay is intended for the qualitative determination of specific IgG antibodies to Toxoplasma gondii in human serum using chemiluminescent immunoassay (CLIA) technology on the LIAISON® XL Analyzer. The results aid in assessing a patient's serological status to Toxoplasma gondii infection and in determining the immune status of individuals, including pregnant women.

The study supporting this device's acceptance focused on comparative clinical studies against a predicate device and a CDC panel study.

1. Table of Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state "acceptance criteria" in a quantitative format for clinical performance (e.g., minimum sensitivity/specificity thresholds). However, substantial equivalence is claimed based on agreement with a predicate device and a CDC panel. The performance data presented indicates the device aims to accurately identify positive and negative Toxoplasma gondii IgG samples.

Here's a summary of the reported device performance from the studies:

2. Sample Sizes and Data Provenance

• Prospective US Population Test Set:
  • Sample Size: 204 individuals
  • Data Provenance: Prospective, US subjects sent to the lab for Toxoplasma gondii IgG testing.
• Prospective European Population Test Set:
  • Sample Size: 600 individuals
  • Data Provenance: Prospective, European subjects sent to the lab for Toxoplasma gondii IgG testing.
• Prospective Pregnant Population Test Set:
  • Sample Size: 202 females
  • Data Provenance: Prospective, pregnant women.
• Retrospective/Pre-Selected Population Test Set:
  • Sample Size: 42 individuals
  • Data Provenance: Retrospective, samples from individuals with a positive Toxoplasma gondii IgG result by the comparator assay.
• CDC Panel Study Test Set:
  • Sample Size: 100 frozen blind specimens (70 true positive, 30 true negative)
  • Data Provenance: CDC Toxoplasma 1998 Human Serum Panel.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test sets derived from the comparative clinical studies (US, European, Pregnant, Retrospective populations). The comparison was made against a "comparator assay" (Diamedix Is-Toxoplasma IgG ELISA). For the CDC panel study, the results were submitted to the "CDC (Reference Immunodiagnostic Lab, Biology and Diagnostic Branch Division of Parasitic Diseases) for data analysis," implying that CDC's established ground truth, likely based on expert consensus and/or confirmatory testing, was used.

4. Adjudication Method

The document does not describe a formal adjudication method for discrepancies in the comparative clinical studies. It presents agreement percentages between the new device and the comparator assay. For the CDC panel, the results were submitted to and analyzed by the CDC, which inherently implies an adjudication (or definitive classification) by that reference lab.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done. This device is an automated in vitro diagnostic assay, not an imaging or interpretive AI device that would typically involve multiple human readers.

6. Standalone Performance

Yes, a standalone performance study was done. The "Comparison to Predicate Device" section and the "Performance Data: Comparative Clinical Studies" detail the performance of the LIAISON® Toxo IgG II assay (the algorithm/device only) in comparison to a predicate device and a CDC reference panel. The results (e.g., percent agreement, sensitivity, specificity) demonstrate its performance independent of human interpretation other than reading the instrument's output.

7. Type of Ground Truth Used

• For Comparative Clinical Studies (Prospective and Retrospective populations): The ground truth was established by a "comparator assay," specifically the Diamedix Is-Toxoplasma IgG ELISA (K981498). This is a form of expert consensus or reference standard based on an FDA-cleared predicate device.
• For CDC Panel Study: The ground truth was based on the "CDC Toxoplasma 1998 Human Serum Panel," which had true positive and true negative samples validated by the CDC Reference Immunodiagnostic Lab. This represents a highly authoritative, verified ground truth.

8. Sample Size for the Training Set

The document does not specify a separate "training set" sample size. For in vitro diagnostic assays, the development process (which might involve internal optimization, calibration, and iterative testing) is usually distinct from the formal clinical validation studies submitted for regulatory clearance. The provided data focuses on the validation/test sets.

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

As no explicit "training set" is mentioned with details on its ground truth establishment, this information is not available in the provided text. The performance data presented relates to the validation of the finalized device, not its developmental training.

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The LIAISON® Toxo IgM II assay uses chemiluminescent immunoassay (CLIA) technology on the LIAISON® XL Analyzer for the qualitative determination of IgM antibodies to Toxoplasma gondii in human serum samples. It is intended for use as an aid in the presumptive diagnosis of acute or recent Toxoplasma gondii infection, including pregnant women. It is recommended that the LIAISON® Toxo IgM II assay be performed in conjunction with a Toxoplasma gondii IgG assay. This assay has not been cleared/approved by the FDA for blood/plasma donor screening.

The LIAISON Control Toxo IgM II (negative and positive) is intended for use as assayed quality control samples to monitor the performance of the LIAISON Toxo IgM II assay on the LIAISON® XL Analyzer.

The method for qualitative determination of specific IgM to Toxoplasma gondii is an antibody capture chemiluminescence immunoassay (CLIA). The principal components of the test are magnetic particles (solid phase) coated with IgG (mouse, monoclonal) is used for coating magnetic particles (solid phase) and a mouse monoclonal antibody to human IgM, Toxoplasma gondii antigen, and a conjugate of mouse monoclonal antibodies to Toxoplasma gondii linked to an isoluminol derivative (isoluminol-antibody coniugate).

During the first incubation, IgM antibodies present in calibrators, samples or controls bind to the solid phase. During the second incubation, the mouse monoclonal antibody conjugate reacts with Toxoplasma gondii antigen and the immune complex thus formed reacts with IgM already bound to the solid phase. After the incubations, the unbound material is removed with a wash cycle. Subsequently, the starter reagents are added and a flash chemiluminescence reaction is thus induced. The light signal, and hence the amount of isoluminol-antibody conjugate, is measured by a photomultiplier as relative light units (RLU) and is indicative of Toxoplasma gondii IgM concentration present in calibrators, samples or controls.

All assay steps and incubations are performed by the LIAISON® XL Analyzer.

The provided text describes the LIAISON® Toxo IgM II assay, a chemiluminescent immunoassay (CLIA) for the qualitative determination of IgM antibodies to Toxoplasma gondii. Here's a breakdown of the acceptance criteria and the studies performed:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the LIAISON® Toxo IgM II assay are primarily demonstrated through comparative clinical studies, particularly in terms of agreement with a comparator assay and a CDC panel. The document doesn't explicitly state numerical acceptance criteria thresholds (e.g., "must achieve X% sensitivity"), but rather presents the achieved performance. Based on the data provided, implied criteria are high agreement percentages for both negative and positive samples.

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

• Prospective US Population: 204 individuals. Data provenance: US, prospective.
• Prospective European Population: 600 individuals. Data provenance: European, prospective.
• Pregnant Women Population: 201 females. Data provenance: Not specified (likely US or European as part of prospective studies), prospective.
• Retrospective/Pre-Selected Population: 33 samples. Data provenance: Not specified (likely US or European), retrospective.
• CDC Panel Study: 100 frozen blind specimens (32 true positive, 65 true negative, 3 dilutions of 3 true positive samples). Data provenance: CDC (reference panel), retrospective.
• Precision and Reproducibility:
  • Precision study: 80 measurements per sample (one site).
  • Reproducibility study: 480 measurements per sample (three sites).

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

The document does not specify the number or qualifications of experts used to establish the ground truth for the clinical study test sets. It mentions a "comparator assay" and "references" for the CDC panel, implying established methods or expert determinations, but details are not provided.

4. Adjudication Method for the Test Set

The document does not describe any specific adjudication method (e.g., 2+1, 3+1) for the clinical study test sets. The "comparator assay" served as the basis for classification in the prospective and retrospective studies. For the CDC panel, the CDC itself provided the "true positive" and "true negative" categorizations.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This device is a diagnostic assay (an in-vitro diagnostic, IVD), not an image-based AI device designed for human reader assistance. Therefore, the concept of human readers improving with or without AI assistance does not apply.

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

Yes, the performance studies for the LIAISON® Toxo IgM II assay were conducted in a standalone manner. The assay, which is an automated chemiluminescent immunoassay, directly measures and reports results (qualitative determination of IgM antibodies) without human intervention in the interpretation process of the assay's output itself. The results are generated by the LIAISON® XL Analyzer.

7. The Type of Ground Truth Used

• Clinical Studies (Prospective and Retrospective): The ground truth was established by a "comparator assay" (Diamedix Is-Toxoplasma IgM Capture Test System (K001707)).
• CDC Panel Study: The ground truth was established by the "CDC (Reference Immunodiagnostic Lab, Biology and Diagnostic Branch Division of Parasitic Diseases)" which categorized samples as "Toxoplasma IgM true positive" and "Toxoplasma IgM true negative." This represents a form of expert consensus and reference laboratory determination.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" for an algorithm, as this is an IVD assay, not a machine learning model in the typical sense. The assay is built on established biochemical principles and reagents. Therefore, the concept of a training set for an AI/algorithm is not directly applicable. If one were to interpret "training" in the context of assay development, it would refer to the optimization and validation experiments conducted during the assay's development prior to the reported clinical studies, but no sample sizes for such development phases are provided.

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

Since there is no explicit "training set" for an AI algorithm, this question is not directly applicable. The assay's analytical characteristics and performance are based on its chemical and immunological design, calibrated against reference materials and validated using clinical samples.

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