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(1) The Elecsys Rubella IgG immunoassay is for the in vitro quantitative determination of IgG antibodies to rubella virus in human serum and Li-heparin, K3-EDTA and sodium citrate plasma.
This assay may be used as an aid in the assessment of immune status to rubella in individuals including women of childbearing age.
The electrochemiluminescence immunoassay "ECLIA" is intended for use or Elecsys and cobas e immunoassay analyzers.
(2) Elecsys PreciControl Rubella IgG is used for quality control of the Elecsys Rubella IgG immunoassay on the Elecsys and cobas e immunoassay analyzers.

(1) The Elecsys Rubella IgG Immunoassay is a two-step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. The Rubella IgG assay contains: a biotin labeled monoclonal antibody against human IgG, a ruthenium-labeled anti-Rubella antibody fragment , biotin- and ruthenium-labeled Rubella-antigens and a Rubella-like particle. A relationship exists between the concentration of the IgG antibody targets present in a patient sample and the level of signal count detected by the system. The IgG assay is quantitative and is standardized against WHO materials. Results are determined using a calibration curve that is generated specifically on each instrument by a 2 point calibration and a master curve provided with the reagent bar code. The test kit contains the human serum-based calibrators intended for use with the system.
(2) The Elecsys Precicontrol Rubella IgG contains two levels of human serum with Rubella IgG antibodies.

Here's an analysis of the acceptance criteria and supporting studies for the Elecsys Rubella IgG Immunoassay, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The 510(k) summary primarily focuses on demonstrating substantial equivalence to a predicate device, rather than explicit pre-defined acceptance criteria in terms of numerical thresholds for performance metrics. However, we can infer performance goals based on the presented data and the comparison to the predicate device.

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

The 510(k) describes several test sets used for method comparison:

• US Routine Clinical Specimens and Acute/Recent Infection: 500 samples (25 negative, 475 positive). Data provenance is "US Routine Clinical Specimens."
• Banked Samples: 345 samples (145 negative, 200 positive). Data provenance is not explicitly stated but implies collected and stored samples for research or clinical use.
• Samples Collected During a Rubella Outbreak: 71 samples (10 negative, 61 positive). Data provenance is "Rubella Outbreak."
• Pregnant Women: 150 serum samples. Data provenance is "US."
• Vaccinated Individuals: 15 samples from 13 subjects (commercially available vaccination follow-up panels). Data provenance is commercially available panels.
• Low Positive Samples: 84 serum samples. Data provenance is not explicitly stated, but these were samples that gave low positive on the reference assay.

All mentioned samples appear to be retrospective as they were collected and then tested.

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

The document does not explicitly state the "number of experts" or their "qualifications" used to establish the ground truth for the test sets. For immunoassay devices like this, the "ground truth" is typically established by the results of a reference assay (often a well-established, previously cleared or gold-standard laboratory method) or clinical correlation (e.g., confirmed infection during an outbreak).

In this case, the predicate device, Zeus Scientific Rubella IgG ELISA Test System (K984180), serves as the primary comparator for establishing agreement, and its results are implicitly treated as the ground truth or reference standard for comparison. The performance of the predicate device would have been established through its own clinical trials and regulatory clearance.

4. Adjudication Method (e.g., 2+1, 3+1, none) for the Test Set

The document does not describe an adjudication method with multiple readers or experts to resolve discrepancies for the test set. Instead, it directly compares the Elecsys Rubella IgG Immunoassay results against the predicate device's results. Any discrepancies are reported as part of the agreement percentages.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is an automated in vitro diagnostic immunoassay, not an AI-assisted diagnostic imaging or pathology tool involving human "readers" interpreting results. Its performance is evaluated biochemically against a reference method.

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

Yes, the performance studies described are for the Elecsys Rubella IgG Immunoassay in a standalone fashion. The assay automatically processes samples and provides quantitative results (IU/mL) without direct human intervention in the result determination process once the sample is loaded and the assay run begins. The results are then interpreted by a healthcare professional in a clinical context.

7. The Type of Ground Truth Used

The primary "ground truth" used for performance evaluation is the results obtained from the legally marketed predicate device, the Zeus Scientific Rubella IgG ELISA Test System (K984180).

Additionally, for specific study cohorts:

• For "US Routine Clinical Specimens and Acute/Recent Infection," the classification might be based on clinical diagnosis (acute/recent infection) or general population screening.
• For "Rubella Outbreak," the classification of samples as negative/positive would likely be based on epidemiological and/or confirmatory testing methods during the outbreak.
• For "Vaccinated Individuals," the expected positive status is derived from the history of vaccination.

8. The Sample Size for the Training Set

The 510(k) summary does not specify a separate "training set" in the context of machine learning or AI models. For an immunoassay, the equivalent of a "training set" would be the samples used during product development and optimization (e.g., to establish calibration curves, optimize reagent concentrations, and define cut-offs). This information is typically proprietary and not detailed in a 510(k) summary, which focuses on validation data demonstrating substantial equivalence to a predicate. The document mentions a master curve provided with the reagent bar code, implying an internal standardization process.

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

As noted above, a distinct "training set" with ground truth in the AI sense is not applicable. For general immunoassay development and standardization, the "ground truth" for calibrators and controls is typically established through:

• Traceability to International Reference Standards: The Elecsys Rubella IgG Immunoassay explicitly states traceability to the "1st International Standard for Anti-Rubella Immunoglobulin, human, NIBSC RUBI-1-94; formerly referred to as proposed 3rd WHO Reference Standard Preparation." This WHO standard serves as the ultimate ground truth for quantitative accuracy.
• Internal Reference Methods and Protocols: Manufacturers use their own established reference methods and rigorous internal studies to characterize and assign values to calibrators and controls, ensuring lot-to-lot consistency and accuracy traceable to international standards.

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