(189 days)
FastPack® Vitamin D Immunoassay is intended for the quantitative determination of total 25-hydroxyvitamin D and other hydroxylated metabolites in human serum and plasma. The assay is to be used as an aid in the assessment of vitamin D sufficiency in adults. The FastPack® Vitamin D Immunoassay is intended for use with the FastPack® Analyzer.
FastPack® Vitamin D Calibrator Kit is used for calibrating the quantitative FastPack® Vitamin D Immunoassay on the FastPack® Analyzer.
FastPack® Vitamin D Control Kit is used for quality control of the FastPack® Vitamin D Immunoassay on the FastPack® Analyzer.
FastPack® Vitamin D Method Verification Kit is used in the quantitative verification of calibration and assay range of the quantitative FastPack® Vitamin D Immunoassay on the FastPack® Analyzer.
The FastPack® Vitamin D Immunoassay employs a competitive immunoassay principle. Endogenous Vitamin D in a patient sample, calibrator, control, or verifier is mixed with pretreatment buffer then added into a FastPack® reagent pack. In the reagent pack, the pre-treated Vitamin D sample binds with a monoclonal (mouse) anti-Vitamin D antibody covalently linked to alkaline phosphatase (ALP). After incubation, a conjugate of Vitamin D-Biotin linked to streptavidin coated paramagnetic particles is added. Monoclonal anti-Vitamin D antibody-ALP conjugate not reacted with Vitamin D in the sample will bind to unoccupied binding sites of the Vitamin D-biotin conjugate bound to the streptavidin paramagnetic particles. After washing steps (using a Tris buffer containing detergents) to separate bound from unbound anti-Vitamin D monoclonal antibody-ALP, a chemiluminogenic substrate mixture is added to the system. This mixture contains indoxyl-3-phosphate, a substrate for ALP, and lucigenin (N.Ndimethyl-9,9'-biacridinium dinitrate). ALP dephosphorylates indoxyl-3-phosphate to indol-3-ol, which subsequently undergoes oxidation. As a result, lucigenin is reduced to form a dioxetane structure that is cleaved to yield N-methylacridone. This compound produces a sustained luminescent glow following excitation. The raw relative luminescence units (RLUs) generated are measured by a photomultiplier tube in the FastPack® Analyzer and are inversely proportional to the concentration of Vitamin D in the sample. The entire reaction sequence takes place at 37 ± 0.5 ℃ and is protected from external light.
The Qualigen FastPack® Vitamin D Immunoassay is an in-vitro diagnostic device intended for the quantitative determination of total 25-hydroxyvitamin D and other hydroxylated metabolites in human serum and plasma, to be used as an aid in the assessment of vitamin D sufficiency in adults. The device demonstrated substantial equivalence to the LIAISON® 25 OH Vitamin D TOTAL Assay (K112725). The following information details its acceptance criteria and supporting studies.
1. Acceptance Criteria and Reported Device Performance
The acceptance criteria for this device are implicitly derived from the comparative performance against the predicate device (DiaSorin LIAISON® 25 OH Vitamin D TOTAL Assay) and established clinical laboratory guidelines for precision, linearity, limits of detection/quantitation, cross-reactivity, and interference. While explicit acceptance criteria values are not provided in all sections, the reported performance is presented to demonstrate that the device functions comparably or within reasonable assay limits.
| Performance Metric | Acceptance Criteria (Implicitly from Predicate / Guidelines) | Reported Device Performance (FastPack® Vitamin D Immunoassay) |
|---|---|---|
| Precision | Within-Run: ≤ 15.1% (Predicate: ≤ 7.7%) | |
| Sample 1 | N/A | 10.2% CV (Analyzer 1, Lot 1); 15.1% CV (Analyzer 2, Lot 2) |
| Sample 2 | N/A | 10.7% CV (Analyzer 1, Lot 1); 11.2% CV (Analyzer 2, Lot 2) |
| Sample 3 | N/A | 8.5% CV (Analyzer 1, Lot 1); 7.5% CV (Analyzer 2, Lot 2) |
| Sample 4 | N/A | 4.8% CV (Analyzer 1, Lot 1); 4.1% CV (Analyzer 2, Lot 2) |
| Total Precision (Inter-assay) | ≤ 15.1% (Predicate: ≤ 12.6%) | |
| Sample 1 | N/A | 13.4% CV (Analyzer 1, Lot 1); 15.1% CV (Analyzer 2, Lot 2) |
| Sample 2 | N/A | 12.1% CV (Analyzer 1, Lot 1); 12.7% CV (Analyzer 2, Lot 2) |
| Sample 3 | N/A | 9.5% CV (Analyzer 1, Lot 1); 7.9% CV (Analyzer 2, Lot 2) |
| Sample 4 | N/A | 6.1% CV (Analyzer 1, Lot 1); 4.7% CV (Analyzer 2, Lot 2) |
| Limit of Blank (LOB) | N/A | 2.3 ng/mL |
| Limit of Detection (LOD) | N/A | 6.2 ng/mL |
| Limit of Quantitation (LOQ) | N/A | 12.9 ng/mL |
| Linearity Range | Predicate: LOQ (4.0 ng/mL) to 150 ng/mL | LOQ (12.9 ng/mL) to 150.0 ng/mL |
| Cross-reactivity | `0.9) and acceptable bias | Serum vs. EDTA Plasma: R=0.979, Slope=0.993, y-int=-6.3; Serum vs. Lithium-Heparin Plasma: R=0.971, Slope=0.970, y-int=-0.7 |
| Method Comparison (vs. Predicate) | Correlation coefficient (R) > 0.9, Slope close to 1, small y-intercept | N=137; R = 0.92 (0.90-0.94 CI), Slope = 0.97 (0.88-1.06 CI), y-intercept = -4.6 (-8.9 to -0.25 CI) |
2. Sample Sizes Used for the Test Set and Data Provenance
- Precision Study: 4 samples tested in duplicate on two analyzers, with two reagent lots, over 20 days. This resulted in 160 replicate determinations for each sample (80 replicates per lot/analyzer).
- LOB/LOD/LOQ Determination: Specific sample size not explicitly stated but conducted according to CLSI EP17-A.
- Linearity Study: A high patient sample was intermixed with a low sample to generate 9 concentration levels, each tested in duplicate. Specific number of patient samples not explicitly stated.
- Cross-reactivity Study: Two samples (low and high Vitamin D concentrations) were tested with and without added potential cross-reacting compounds. Specific number of samples per compound not explicitly stated.
- Interference Study: Specific number of samples not explicitly stated; substances were tested at noted concentrations.
- Serum and Plasma Equivalence: 32 volunteers provided blood samples (serum, EDTA plasma, lithium-heparin plasma).
- Expected Values/Reference Intervals: 367 subjects.
- Method Comparison: 137 human serum samples.
Data Provenance:
The document does not explicitly state the country of origin for all samples. However, for the "Expected Values/Reference Intervals" study, serum samples from 367 subjects were acquired from 4 different sources representing 5 different geographic regions of the United States. This suggests at least a portion of the clinical data is from the US. The studies are prospective in nature, designed specifically to evaluate the device performance.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and the Qualifications of Those Experts
The document does not describe the use of human experts to establish "ground truth" for the test sets in the traditional sense of diagnostic image interpretation. This device is a quantitative immunoassay. The "ground truth" for method comparison and equivalence studies is established by comparison to a legally marketed predicate device (LIAISON® 25 OH Vitamin D TOTAL Assay) or by highly controlled analytical methods (e.g., for linearity, LOB/LOD/LOQ, cross-reactivity, interference). Therefore, the concept of "experts" and their qualifications for establishing ground truth as in imaging studies is not directly applicable here. The accuracy of measurements on the predicate device or the analytical standards used would serve as the reference.
4. Adjudication Method for the Test Set
Not applicable. As a quantitative immunoassay, the "adjudication method" in the context of expert consensus (e.g., 2+1, 3+1) is not relevant. The results are quantitative values derived from the immunoassay and compared against analytical standards, reference methods, or statistical criteria.
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 device is a laboratory immunoassay for quantitative measurement of Vitamin D, not an AI-based diagnostic imaging or interpretive tool requiring human readers. Therefore, an MRMC study and analysis of human reader improvement with AI assistance are not relevant.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was Done
The performance studies described are inherently "standalone" in the context of the device's function. The FastPack® Vitamin D Immunoassay, run on the FastPack® Analyzer, provides a quantitative result. The studies assess the analytical performance of this automated system directly (e.g., precision, linearity, limits, interference, method comparison with a predicate device), without human interpretive input affecting the direct measurement output. The human involvement would be in operating the instrument and interpreting the resulting quantitative value in a clinical context, which is outside the scope of the device's standalone analytical performance.
7. The Type of Ground Truth Used
The ground truth used for various studies includes:
- Predicate Device Measurements: For the method comparison study, results from the LIAISON® 25 OH Vitamin D TOTAL Assay (K112725) were used as the reference "ground truth" for comparison.
- Reference Standards/Known Concentrations: For linearity, LOB/LOD/LOQ, cross-reactivity, and interference studies, the "ground truth" is established by using samples with known, carefully prepared, or spiked concentrations of analytes and interfering substances.
- Paired Sample Measurements: For serum/plasma equivalence, the "ground truth" is the quantitative value obtained from one matrix (e.g., serum) against which measurements from another matrix (e.g., plasma) are compared.
8. The Sample Size for the Training Set
Not applicable. This device is a traditional immunoassay, not an AI/machine learning model that typically requires a "training set." The development of the assay involves chemical and biological optimization, not algorithm training on a dataset.
9. How the Ground Truth for the Training Set was Established
Not applicable, as no training set (in the AI/ML sense) was used for this traditional immunoassay device.
§ 862.1825 Vitamin D test system.
(a)
Identification. A vitamin D test system is a device intended for use in clinical laboratories for the quantitative determination of 25-hydroxyvitamin D (25-OH-D) and other hydroxylated metabolites of vitamin D in serum or plasma to be used in the assessment of vitamin D sufficiency.(b)
Classification. Class II (special controls). Vitamin D test systems must comply with the following special controls:(1) Labeling in conformance with 21 CFR 809.10 and
(2) Compliance with existing standards of the National Committee on Clinical Laboratory Standards.