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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.

Device Description

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.

AI/ML Overview

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.

Performance Metric	Acceptance Criteria (Implied/Design Goal)	Reported Device Performance	Study Type
Method Comparison/Accuracy	High agreement with predicate device		Method Comparison
Positive Percent Agreement (PPA)	N/A (demonstrated 100% agreement)	100% (95% CI: 91.43% to 100.00%)	Method Comparison (Access 2 vs. DxI 9000)
Negative Percent Agreement (NPA)	N/A (demonstrated 100% agreement)	100% (95% CI: 96.53% to 100.00%)	Method Comparison (Access 2 vs. DxI 9000)
Imprecision (Within-Laboratory)	≤ 20.0% CV (Design Goal)		Precision (CLSI EP05-A3)
Sample 1 (Non-Reactive) Overall CV%	≤ 20.0%	6.8%	Within-Laboratory Precision
Sample 2 (Reactive, Low) Overall CV%	≤ 20.0%	5.9%	Within-Laboratory Precision
Sample 3 (Reactive, Mid) Overall CV%	≤ 20.0%	5.9%	Within-Laboratory Precision
Sample 4 (Reactive, High) Overall CV%	≤ 20.0%	5.7%	Within-Laboratory Precision
Imprecision (Reproducibility)	N/A (Overall CV% for precision)		Reproducibility (CLSI EP05-A3)
Sample 1 (Non-Reactive) Overall CV%	N/A (demonstrated acceptable precision)	6.8%	Reproducibility
Sample 2 (Reactive, Low) Overall CV%	N/A (demonstrated acceptable precision)	5.3%	Reproducibility
Sample 3 (Reactive, Mid) Overall CV%	N/A (demonstrated acceptable precision)	4.1%	Reproducibility
Sample 4 (Reactive, High) Overall CV%	N/A (demonstrated acceptable precision)	4.6%	Reproducibility

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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K Number

K003259

Device Name

ACCESS TOXO IGM II REAGENTS FOR USE ON THE ACCESS IMMUNOASSAY SYSTEMS, MODEL 34470,34475,34479

Manufacturer

BECKMAN COULTER, INC.

Date Cleared

2001-06-13

(238 days)

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