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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.

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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

• Negative Control: SD 0.014 (NAc)
• Positive Control: SD 0.104 (3.8% CV)
• High Nonreactive Panel: SD 0.040 (NAc)
• Low Reactive Panel: SD 0.064 (4.7% CV)
• Reactive Panel: SD 0.109 (4.3% CV)

Reproducibility (5-Day, Multi-Site):

• Negative Control: SD 0.018 (NAc)
• Positive Control: SD 0.132 (5.1% CV)
• High Nonreactive Panel: SD 0.041 (NAc)
• Low Reactive Panel: SD 0.067 (5.1% CV)
• Reactive Panel: SD 0.136 (5.5% CV)
  (Overall low CVs demonstrate good precision.) |
  | Analytical Specificity (Interfering Substances) | No significant interference from common endogenous substances, other conditions, or drugs at specified concentrations. | Endogenous Substances: No significant interference observed for Unconjugated Bilirubin (40 mg/dL), Conjugated Bilirubin (40 mg/dL), Hemoglobin (1000 mg/dL), Total Protein (15 g/dL), Triglycerides (3000 mg/dL).
  Other Conditions: No significant interference observed for HAMA (800 ng/mL), RF (200 IU/mL).
  Drugs: No significant interference observed for Ascorbic Acid (300 mg/L), Atovaquone (120 mg/L), Beta Carotene (6 mg/L), Biotin (4250 ng/mL), Clindamycin (5.1 mg/dL), Folic Acid (100 nmol/L), Pyrimethamine (15 mg/L), Spiramycine (4.2 mg/L), Sulfadiazine (25.5 mg/dL), Sulfamethoxazole (210 mg/dL), Trimethoprim (4.2 mg/dL). |
  | Cross-Reactivity | Minimal false reactive results from individuals with other medical conditions and high titer Toxoplasmosis IgG. | Out of 177 specimens from individuals with various unrelated conditions (e.g., CMV, EBV, HSV, Flu vaccine recipients, Syphilis, etc.) and high titer Toxoplasmosis IgG, only 1 out of 10 RF (Rheumatoid Factor) specimens resulted in a false reactive result. |
  | Matrix Equivalency | Acceptable performance across different blood collection tube types (serum, serum separator, lithium heparin plasma, lithium heparin plasma separator, and tripotassium EDTA plasma). | All tested blood collection tube types were found acceptable for use with the Alinity i Toxo IgM assay. |
  | Class Specificity | Reactivity only to human anti-Toxoplasma IgM and no reactivity to human anti-Toxoplasma IgG. | Demonstrated reactivity only to human anti-Toxoplasma IgM, with no reactivity to human anti-Toxoplasma IgG. |
  | CDC Panel Agreement | High positive and negative percent agreement with the CDC Toxoplasma 1998 Human Serum Panel. | PPA: 100.00% (32/32) with 95% CI (89.28%, 100.00%)
  NPA: 100.00% (65/65) with 95% CI (94.42%, 100.00%) |
  | Clinical Agreement | High positive and negative percent agreement with an FDA-cleared predicate assay. | Population 1 (n=897):
• PPA: 94.94% (150/158) with 95% CI (90.33%, 97.41%)
• NPA: 94.44% (697/738) with 95% CI (92.55%, 95.88%)
  Population 2 (pregnant women, n=234):
• PPA: 94.74% (18/19) with 95% CI (75.36%, 99.06%)
• NPA: 100.00% (215/215) with 95% CI (98.24%, 100.00%) |

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.

• Positive Control 1: Mean 6.4 IU/mL, SD 0.16 IU/mL (2.5 %CV)
• Other Panels: %CVs for Panels 3, 4, 5 were 3.8%, 2.8%, 2.5% respectively. |
  | Lower Limits of Measurement (LoB, LoD, LLoQ within acceptable ranges) | - LoB: 0.1 IU/mL
• LoD: 0.2 IU/mL
• LLoQ: 0.2 IU/mL (at 20% CV) |
  | Linearity (Assay measures concentrations accurately across a range) | Linear across 0.2 to 75.0 IU/mL. |
  | Analytical Specificity / Interference (No significant interference from common substances or cross-reacting conditions) | - No significant interference observed from listed endogenous substances (e.g., Bilirubin, Hemoglobin, Triglycerides) and drugs (e.g., Ascorbic Acid, Atovaquone).
• Zero reactive results (0/164) from specimens with various potentially interfering medical conditions (e.g., other viral infections, autoimmune markers, rheumatoid factor). |
  | CDC Panel Agreement (High agreement with a well-characterized reference panel) | - Sensitivity (Positive Agreement): 97% (68/70 positive specimens detected as reactive)
• Specificity (Negative Agreement): 100% (30/30 negative specimens detected as nonreactive) |
  | System Reproducibility (Multi-site) (Consistent performance across different sites/operators) | - Negative Control: Mean 0.0 IU/mL, SD 0.02 IU/mL (N/A %CV)
• Positive Control 1: Mean 6.4 IU/mL, SD 0.22 IU/mL (3.5 %CV)
• Other Panels: Reproducibility %CVs for Panels 3, 4, 5 were 5.6%, 5.9%, 6.7% respectively. |
  | Percent Agreement with Predicate Device (High agreement with a legally marketed comparator) | - Routine Order Samples:
  • Negative % Agreement: 98.54% (1082/1098)
  • Positive % Agreement: 94.87% (148/156)
• Preselected Positive Samples:
  • Negative % Agreement: 100.00% (1/1)
  • Positive % Agreement: 96.73% (148/153)
• Pregnant Females Samples:
  • Negative % Agreement: 100.00% (186/186)
  • Positive % Agreement: 93.33% (14/15) |

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:

• Positive agreement: 66.7% (2/3)
• Negative agreement: 98.6% (431/437)
  Study 2 (US Retrospective, n=60):
• Positive agreement: NA (0/0)
• Negative agreement: 98.3% (59/60)
  Study 3 (EU Prospective, General Population, n=101):
• Positive agreement: 94.2% (81/86)
• Negative agreement: 50.0% (7/14)
  Study 3 (EU Prospective, Pregnant Women, n=87):
• Positive agreement: 93.2% (68/73)
• Negative agreement: 53.9% (7/13) |
  | Interference | Unaffected by high concentrations of Bilirubin, Hemoglobin, Intralipid, and Biotin (within specified limits). No interference from rheumatoid factors (up to 3720 IU/mL) or 18 common pharmaceuticals. Noted potential interference from unspecific IgM and, in rare cases, high titers of antibodies to immunological components, streptavidin or ruthenium. |

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 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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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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The VIDAS® TOXO IgG Avidity assay is an automated qualitative test for the determination of anti-toxoplasma IgG avidity in human serum using the ELFA technique (Enzyme Linked Fluorescent Assay). The VIDAS® TOXO IgG Avidity assay is intended for use in conjunction with results from the VIDAS TOXO IgG II and must have a positive titer (> 8 IU/mL); other laboratory findings and clinical information to aid in the presumptive exclusion of a recently acquired (

The VIDAS® TOXO IgG Avidity assay is an automated qualitative test for the determination of anti-toxoplasma IqG avidity in human serum using the ELFA technique (Enzyme Linked Fluorescent Assay). The VIDAS® TOXO IgG Avidity assay is intended for use in conjunction with results from the VIDAS TOXO IqG II and must have a positive titer (> 8 IU/mL); other laboratory findings and clinical information to aid in the presumptive exclusion of a recently acquired (

The provided document describes the VIDAS® TOXO IgG Avidity Assay, an automated qualitative test for determining anti-toxoplasma IgG avidity in human serum. It is intended to aid in the presumptive exclusion of a recently acquired (≤ 4 months) Toxoplasma gondii infection in pregnant women and patients with lymphadenopathy, in conjunction with other laboratory and clinical findings.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state "acceptance criteria" as clear numerical targets. Instead, it presents several analytical performance metrics for the VIDAS® TOXO IgG Avidity Assay, which inherently serve as the data demonstrating its performance. For comparison, the document also includes data for the predicate device, VIDAS® TOXO IgM Assay.

2. Sample Size for the Test Set and Data Provenance

The document refers to "non-clinical (analytical) comparison" data, which typically represents testing done for analytical performance rather than clinical validation of diagnostic accuracy with patient samples.

• Precision Studies:
  • Within-run Precision: n = 80 replicates at each of 3 sites (total 240 replicates per avidity level).
  • Between-Run Precision: n = 40 runs at each of 3 sites.
  • Total Precision: n = 120 runs (2 runs per day, for 10 days with 2 reagent lots, at 3 sites).
• Cross-Reactivity: Number of samples varies by condition (e.g., 12 samples tested for HSV-1 disease, others are not specified with counts beyond "samples from patients with...").
• Interfering Substances: Not specified with sample counts but indicates testing was done up to certain concentrations.
• Drug Interference: Not specified with sample counts but indicates testing was done at specific drug concentrations.

Data Provenance: The document does not explicitly state the country of origin for the samples or if the data is retrospective or prospective. It is clinical laboratory data, generated during the analytical validation of the assay.

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

The document describes analytical performance studies (precision, cross-reactivity, interference). For these types of analytical studies, the "ground truth" is typically defined by controlled experimental conditions (e.g., known concentrations, spiked samples, well-characterized panels) rather than expert clinical consensus. Therefore, expert involvement for establishing ground truth in this context is not applicable.

4. Adjudication Method for the Test Set

Adjudication methods (like 2+1, 3+1) are typically used in clinical studies to establish a consensus ground truth from multiple expert readings of patient cases. Since this document focuses on analytical performance rather than diagnostic accuracy with expert-adjudicated clinical cases, no such adjudication method is mentioned or relevant to the data presented.

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

No, the document does not describe a Multi-Reader Multi-Case (MRMC) comparative effectiveness study. The studies detailed are analytical performance evaluations of the assay itself, not studies comparing human reader performance with or without AI assistance. The device is a diagnostic assay, not an AI-powered image analysis tool or decision support system for human readers.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, the studies presented are standalone performance evaluations of the VIDAS® TOXO IgG Avidity Assay. The assay is an automated qualitative test that provides results directly. The analytical performance data (precision, cross-reactivity, interference) are all measures of the algorithm's/device's performance without human intervention in the result determination. The document states, "All of the assay steps are performed automatically by the instrument. The reaction medium is cycled in and out of the SPR several times. During the final detection step... results are automatically calculated by the instrument and then printed out."

7. The Type of Ground Truth Used (Expert Consensus, Pathology, Outcomes Data, etc.)

For the analytical studies presented, the "ground truth" was established by:

• Known Characteristics of Controls/Samples: For precision studies, standardized controls or characterized samples with known avidity levels were used.
• Known Presence/Absence of Interferents/Cross-Reactants: For cross-reactivity and interference studies, samples were either known to contain specific cross-reactants/interferents or were spiked with them at defined concentrations.

This type of ground truth is based on the intrinsic properties of the test materials and the controlled experimental setup, which is standard for analytical validation of in vitro diagnostic devices. Clinical ground truth (e.g., confirmed toxoplasmosis infection status based on pathology or long-term clinical outcome) would be established in a clinical performance study, which is distinct from the analytical studies described here.

8. The Sample Size for the Training Set

The document describes pre-market analytical performance data for a diagnostic assay. It does not mention a "training set" or "test set" in the context of machine learning or AI development. The data presented are from validation studies of the finished device. Therefore, information on a training set size is not applicable in this context.

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

As explained in point 8, the concept of a "training set" for an AI or machine learning model is not applicable to the analytical validation of this in vitro diagnostic assay.

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

The modified ADVIA Centaur Toxo G Assay is comprised of the following:

ADVIA Centaur Toxo G ReadyPack® Primary Reagent Pack, including:

ADVIA Centaur Toxo G Lite Reagent (10.0 mL/reagent pack)

purified T. gondii p30 antigen (~0.75 µg/mL) complexed with mouse antip30 monoclonal antibody (F(ab)2 fragment) labeled with acridinium ester in protein buffer with surfactant and preservatives

ADVIA Centaur Toxo G Solid Phase (25.0 mL/reagent pack)

mouse anti-human IgGE monoclonal antibody (~0.3 mg/mL) covalently coupled to paramagnetic particles in protein buffer with surfactant and preservatives

ADVIA Centaur Toxo G Calibrators (1.0 mL/vial)

processed defibrinated human plasma positive for toxoplasma IgG antibodies with preservatives

ADVIA Centaur Toxo G Quality Control Material (2.7 mL/vial)

processed defibrinated human plasma negative and positive for toxoplasma igG antibodies with preservatives

The provided text describes a 510(k) premarket notification for a modified immunoassay, the ADVIA Centaur® Toxoplasma IgG (Toxo G) Assay. The purpose of the submission is to demonstrate substantial equivalence to a predicate device, not to present a new study with specific acceptance criteria and performance metrics for regulatory approval of a novel device.

Therefore, the document does not contain the information requested in points 1-7, and 9 about acceptance criteria, device performance, sample sizes for test sets, expert ground truth establishment, adjudication methods, MRMC studies, or standalone performance, nor does it specify details for the training set (point 8 and 9).

The core of this submission is to show that the modified device is substantially equivalent to the predicate device, meaning its safety and effectiveness are not adversely impacted by minor changes in reagent composition.

Here's what can be extracted from the provided text relevant to the request, focusing on the comparison between the modified and predicate device:

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

The document does not specify formal acceptance criteria in terms of performance metrics (e.g., sensitivity, specificity thresholds) for the modified device against a ground truth. Instead, the "acceptance" is based on demonstrating that the performance claims are unchanged compared to the predicate device, despite the modifications.

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

The document does not detail specific sample sizes for a "test set" in the context of a new efficacy study. It only mentions "performance testing, and verification and validation activities" were conducted to demonstrate substantial equivalence, but without providing details on these studies, their sample sizes, or data provenance.

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):

Not applicable. This type of information is generally found in studies establishing the diagnostic accuracy of a new device against a clinical reference standard, not in a 510(k) submission for a modified device seeking substantial equivalence based on unchanged performance.

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

Not applicable for the same reasons as point 3.

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 is an immunoassay and does not involve human readers interpreting results in the way an AI-assisted diagnostic imaging device would.

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

Not applicable. This phrase is typically used for AI/algorithm-driven diagnostics. This is an in vitro diagnostic immunoassay. While its performance is "standalone" in the sense of the instrument reading and quantifying results, the concept of a "human-in-the-loop" performance as distinct from "standalone" is not applicable here. The device itself performs the measurement.

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

The document does not specify a "ground truth" in the context of a new diagnostic accuracy study. For initial approval of the predicate device, a ground truth for Toxoplasma IgG (e.g., highly characterized clinical samples, possibly confirmed by other reference methods or clinical diagnosis) would have been used. For this 510(k) of a modified device, the "ground truth" for demonstrating substantial equivalence is effectively the performance of the predicate device.

8. The sample size for the training set:

Not applicable. This is an immunoassay, not a machine learning or AI-driven device that requires a "training set" in the conventional sense.

9. How the ground truth for the training set was established:
Not applicable for the same reason as point 8.

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