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The LIAISON® VZV IgG Assay uses chemiluminescence immunoassay (CLIA) technology on the LIAISON® Analyzer for the qualitative detection of specific IgG antibodies to varicella-zoster virus in human serum. This assay can be used as an aid in the determination of previous infection of varicella-zoster virus.

The method for the qualitative determination of specific IgG to varicella- zoster virus is an indirect chemiluminescence immunoassay (CLIA). All assay steps and incubations are performed by the LIAISON® Analyzer.

Varicella-zoster virus antigen is used for coating magnetic particles (solid phase) and a mouse monoclonal antibody to human IgG is linked to an isoluminol derivative (isoluminol-antibody conjugate). During the first incubation, anti-VZV IgG antibodies, present in calibrators, samples or controls, bind to the solid phase. After each incubation, the unbound material is removed with a wash cycle. During the second incubation, the antibody conjugate reacts with anti-VZV IgG already bound to the solid phase. Subsequently, the starter reagents are added and a flash chemiluminescence reaction is induced. The light signal, directly related to the amount of isoluminol-antibody conjugate, is measured by a photomultiplier as relative light units (RLU) and is indicative of the presence of anti-VZV IgG in calibrators, samples or controls.

Here's a breakdown of the acceptance criteria and study information for the DiaSorin LIAISON® VZV IgG device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the clinical trial results. The device aims to demonstrate substantial equivalence to the predicate device.

Reproducibility (3-site, 5-day study with 3 kit lots):

Assay Precision (single-site, 20-day study with 1 kit lot):

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

• General Samples: 745 total samples.

  • 33 equivocal results were excluded from agreement calculations (implied by the statement: "Specimens that were equivocal by both assays were not included in the percent agreement calculation").
  • Resulting in 667 for positive agreement calculation and 77 for negative agreement calculation (after adjusting for equivocal results in the reference assay matched with positive/negative device results).

• Pregnant Women Samples: 689 total samples.

  • 11 equivocal results in the predicate assay and 3 equivocal results in the device were handled in agreement calculation.
  • Resulting in 650 for positive agreement calculation and 39 for negative agreement calculation (after adjusting for equivocal results in the reference assay matched with positive/negative device results).

• Reproducibility/Precision Samples:

  • Reproducibility (3 sites): 9 coded frozen repository samples, plus 4 controls (DiaSorin Neg Ctl, DiaSorin Pos Ctl, Cutoff Ctl, BR Neg Ctl, BR Pos Ctl). Each sample/control tested 60 times (implied 3 sites * X runs * Y replicates per run, totaling 60).
  • Precision (1 site): The same serum samples and controls as the reproducibility study. Each sample/control tested 40 times (quadruplicate over 20 working days).

• Data Provenance: Prospectively-collected U.S. samples.

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

The ground truth was established by a "comparison assay" (Diamedix Is-VZV IgG Test System, K981867), which is another immunoassay. No human experts are mentioned as establishing the ground truth for the clinical agreement studies. For the reproducibility and precision studies, a coded panel of samples was used, but the initial "truth" of these samples (negative, low positive, moderate to high positive) is not attributed to experts.

4. Adjudication Method for the Test Set

No explicit adjudication method (like 2+1 or 3+1) is mentioned. The comparison was directly between the LIAISON® VZV IgG assay and the predicate VZV IgG ELISA. Equivocal results were handled by excluding them from percent agreement calculations or by considering them as non-agreements when the reference assay was equivocal and the LIAISON® result was positive/negative.

5. Multi-reader Multi-case (MRMC) Comparative Effectiveness Study

No multi-reader, multi-case (MRMC) comparative effectiveness study was done. This study focuses on the performance of an automated immunoassay device, not on human reader performance with or without AI assistance.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

Yes, the studies presented are all standalone. The DiaSorin LIAISON® VZV IgG is an automated chemiluminescence immunoassay (CLIA) system. Its performance is measured directly against a predicate immunoassay (clinical agreement) and its own internal consistency (reproducibility and precision). There is no human-in-the-loop component described for these performance evaluations.

7. Type of Ground Truth Used

The "ground truth" for the clinical agreement studies was established by a predicate immunoassay (VZV IgG ELISA). For reproducibility and precision, it was based on known control materials and coded repository samples with established characteristics (negative, low-positive, high-positive).

8. Sample Size for the Training Set

The document does not provide information on the sample size used for the training set of the DiaSorin LIAISON® VZV IgG assay. The provided data is for the validation/test phase of the device.

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

The document does not provide information on how the ground truth for the training set (if any was used for algorithm development) was established. The information focuses on the validation of the device.

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