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510(k) Data Aggregation
(182 days)
LIAISON VZV IgG HT, LIAISON Control VZV IgG HT
The LIAISON® VZV IgG HT assay uses chemiluminescent immunoassay (CLIA) technology for the in vitro qualitative detection of specific IgG antibodies to varicella-zoster virus (VZV) in human serum (with gel and without gel-SST), dipotassium EDTA (K2- EDTA), lithium heparin and sodium heparin plasma samples. This assay is intended as an aid in the determination of previous infection of varicella- zoster virus. The test must be performed on the LIAISON® XL Analyzer. The assay performance in detecting antibodies to VZV in individuals vaccinated with the FDA-licensed VZV vaccine is unknown. The user of this assay is responsible for establishing the performance characteristics with VZV vaccinated individuals.
The LIAISON® VZV IgG HT is an indirect chemiluminescence immunoassay (CLIA) for qualitative detection of specific IgG antibodies to varicella-zoster virus in human serum and plasma.
The LIAISON® Control VZV IgG HT are liquid ready-to-use controls based in human serum and plasma. The negative control is intended to provide an assay response characteristic of negative patient specimens and the positive control is intended to provide an assay response characteristic of positive patient specimens.
The assay and controls are designed for use with DiaSorin LIAISON® analyzer family
Here's an analysis of the provided text regarding the DiaSorin LIAISON® VZV IgG HT device, focusing on acceptance criteria and supporting study details:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for this device are primarily expressed as Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) compared to a predicate device, as well as satisfactory performance in interference, cross-reactivity, precision, and high-dose saturation studies.
| Acceptance Criterion | Requirement/Goal (Implied or Stated) | Reported Device Performance |
|---|---|---|
| Clinical Agreement (vs. Predicate): | ||
| Known Positive Specimens: PPA | High agreement, ideally >95% (common for diagnostic assays) | 99.2% (123/124); 95% CI (95.6%-99.9%) |
| Known Positive Specimens: NPA | High agreement (common for diagnostic assays) | 100% (1/1); 95% CI (20.7%-100%) |
| Known Negative Specimens: PPA | Low false positive rate, ideally 95% | 97.9% (190/194); 95% CI (94.8%-99.2%) |
| Normal Lab Routine Specimens: PPA | High agreement, ideally >95% | 97.4% (556/571); 95% CI (95.7%-98.4%) |
| Normal Lab Routine Specimens: NPA | High agreement, ideally >95% | 98.2% (503/512); 95% CI (96.7%-99.1%) |
| Pregnant Women: PPA | High agreement, ideally >95% | 98.2% (108/110); 95% CI (93.6%-99.5%) |
| Pregnant Women: NPA | High agreement, ideally >95% | 96.0% (24/25); 95% CI (80.5%-99.3%) |
| Potential Interfering Substances: | No interference at specified concentrations for listed endogenous and exogenous substances | No interference observed for all listed substances at specified concentrations. |
| Potential Cross-Reactivity: | No false positives from antibodies to other common infectious agents or medical conditions | No reactive results for any of the 226 tested cross-reactive samples (0/226). |
| Precision (Within-Laboratory): | Acceptable variability (SD and CV%) for negative, near cut-off, low positive, and positive samples | CV% ranges from 1.8% to 23.5% (Total column). Lower for positive controls/samples, higher for negative controls. |
| Reproducibility (Multi-site): | Acceptable variability (SD and CV%) across different sites and days | CV% ranges from 3.2% to 13.0% (Reproducibility column). Lower for positive samples, higher for negative control. |
| High-dose saturation effect: | No misclassification or underestimation of high-titer samples | No sample misclassification and no high-dose saturation effect observed. |
| Analytical sensitivity: | Defined sensitivity at cutoff | 152.4 mIU/mL at cutoff level (1.0 S/CO) |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- Total Clinical Agreement Study: 1544 clinical human serum samples (1543 used in analysis due to one sample with insufficient volume).
- Breakdown: 125 known positive, 200 known negative, 135 pregnant women, and 1084 routine lab specimens.
- Specific sub-studies:
- Interfering Substances: Not specified, but involved VZV IgG antibody negative, around the cut-off, low positive, and high positive samples.
- Cross-Reactivity: 226 samples from various conditions.
- Precision (Within-Lab): 7 samples (panel of coded samples) tested 240 times each.
- Reproducibility (Multi-site): 7 samples tested 90 times each across sites.
- High-dose saturation: 3 high-titer samples.
- Analytical sensitivity: Not a sample size of patient specimens, but derived from serial dilutions of WHO International Standard on 3 assay lots.
- Data Provenance: The general clinical samples were collected within the United States. The study was prospective in execution as it involved testing these samples with the new device and comparing them to a predicate, conducted at three independent external laboratories.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document does not explicitly state the number of experts used and their qualifications for establishing the ground truth of the test set.
4. Adjudication Method for the Test Set
The document does not explicitly state an adjudication method (like 2+1, 3+1). The "ground truth" for the clinical agreement study appears to be defined by the results of the FDA cleared predicate device (LIAISON® VZV IgG, K150375), which is referred to as the "comparator." It notes that "Specimens which were repeatedly equivocal by the predicate device were graded against the performance of the LIAISON® VZV IgG HT assay which does not have an equivocal zone." This implies a direct comparison to the predicate's results rather than an independent expert adjudication process for the clinical samples. For cross-reactivity, samples were "pre-screened with another commercially available VZV IgG assay" and then confirmed for the presence of potential cross-reactants using "US-marked assays."
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is an automated in vitro diagnostic assay (CLIA technology) for qualitative detection of antibodies, not an imaging device requiring human reader interpretation or AI assistance in the human-in-the-loop context.
6. Standalone (Algorithm Only) Performance Study
Yes, the entire clinical performance evaluation described (Clinical Agreement, Interfering Substances, Cross-Reactivity, Precision, Reproducibility, High-dose saturation, Analytical Sensitivity) is essentially a standalone algorithm-only performance study. The LIAISON® VZV IgG HT assay is an automated system run on the LIAISON® XL Analyzer, meaning its performance is evaluated without human interpretation of results beyond reading the automated output.
7. Type of Ground Truth Used
The primary ground truth for the clinical agreement study was established by the FDA cleared predicate device (LIAISON® VZV IgG, K150375). For the "known positive" and "known negative" specimens, their status was pre-determined, likely by previous clinical diagnosis or established VZV serology results (though the exact method for this is not detailed beyond being "known"). For cross-reactivity studies, ground truth was based on positive results from "US-marked assays" for the specific cross-reacting agent.
8. Sample Size for the Training Set
The document does not specify a training set sample size. This is typical for in vitro diagnostic (IVD) assays like this one. While there is an "algorithm" (the CLIA technology and interpretation logic), it's not a machine learning model that undergoes a separate training phase with a distinct dataset in the way a medical imaging AI would. The "development" and "optimization" of such assays usually happen using internal samples and established chemical/biological principles, not a formalized, reported training set size like in AI/ML submissions.
9. How the Ground Truth for the Training Set Was Established
Since a formalized "training set" for a machine learning algorithm isn't explicitly mentioned or directly applicable in the typical sense for this type of IVD, the concept of establishing ground truth for it is also not directly addressed. The assay's performance characteristics are developed and validated based on its underlying chemical and biological reactions and internal testing, which ensures it correctly identifies VZV IgG antibodies.
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