(90 days)
The Access Ferritin assay is a paramagnetic particle, chemiluminescent immunoassay for the quantitative determination of ferritin levels in human serum and plasma (heparin) using the Access Immunoassay Systems. Ferritin is used as an aid in the diagnosis of iron deficiency or iron overload.
The Access Ferritin assay is a sandwich immunoenzymatic assay. The Access Ferritin assay consists of the reagent pack and calibrators. Other items needed to run the assay include substrate and wash buffer. The Access Ferritin assay reagent pack, Access Ferritin assay calibrators, along with the UniCel Dxl Wash Buffer II are designed for use with the Dxl 9000 Access Immunoassay Analyzer in a clinical laboratory setting.
Here's an analysis of the provided text, focusing on acceptance criteria and study details:
Device Name: Access Ferritin
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Design Goal) | Reported Device Performance |
|---|---|---|
| Method Comparison | ||
| R² | ≥ 0.90 | 0.99 |
| Slope | 1.00 ± 0.09 | 0.96 (95% CI: 0.95-0.97) |
| Intercept | Not explicitly stated as a numerical acceptance criterion, but implied to be near zero. | 0.23 (95% CI: -0.34-1.1) |
| Precision (Within-Laboratory Imprecision) | ||
| Concentrations ≤ 5 ng/mL (µg/L) | ≤ 0.5 ng/mL (µg/L) SD | Sample 1 (1.2 ng/mL): 0.2 ng/mL SD (17.3% CV). Note: While the SD (0.2) is below 0.5, the CV (17.3%) is high. The acceptance criterion is specifically for SD, so it meets the criterion numerically, but the CV suggests variability at this low concentration. |
| Concentrations > 5 ng/mL (µg/L) | ≤ 10.0% CV | Sample 2 (13 ng/mL): 4.7% CV |
| Sample 3 (147 ng/mL): 5.3% CV | ||
| Sample 4 (289 ng/mL): 4.3% CV | ||
| Sample 5 (560 ng/mL): 4.6% CV | ||
| Sample 6 (1276 ng/mL): 5.3% CV | ||
| (All samples well within the 10.0% CV criterion) | ||
| Linearity | Linear throughout the analytical measuring interval of 0.6-1,500 ng/mL | Linear on the Dxl 9000 Access Immunoassay Analyzer throughout the analytical measuring interval of approximately 0.6-1,500 ng/mL. (Implied to meet the criterion) |
| Limit of Blank (LoB) | ||
| Claimed LoB | 0.2 ng/mL | The claimed LoB for Access Ferritin assay is 0.2 ng/mL on Dxl 9000 Access Immunoassay Analyzer. (Implied to meet, as this is the stated claim derived from the study) |
| Limit of Detection (LoD) | ||
| Claimed LoD | 0.4 ng/mL | The claimed LoD estimate for the Access Ferritin assay is 0.4 ng/mL on Dxl 9000 Access Immunoassay Analyzer. (Implied to meet, as this is the stated claim derived from the study) |
| Limit of Quantitation (LoQ) | ||
| Maximum claimed LoQ (@ ≤ 20% within-lab CV) | 0.6 ng/mL | The maximum claimed LoQ (≤ 20% within-lab CV) determined for the Access Ferritin assay is 0.6 ng/mL on Dxl 9000 Access Immunoassay Analyzer. (Implied to meet, as this is the stated claim derived from the study) |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size (Method Comparison): 147 samples
- Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective for the method comparison samples. It only mentions "patient samples" in the context of the CLSI guidance document referenced (CLSI EP09c: Measurement Procedure Comparison and Bias Estimation Using Patient Samples).
- Test Set Sample Size (Precision, LoB, LoD, LoQ):
- Precision: 80 replicates for each of the 6 concentration levels (1.2, 13, 147, 289, 560, 1276 ng/mL) are reported in the table. The study design mentions "tested multiple samples in duplicate in 2 runs per day for a minimum of 20 days," which would result in 80 measurements (2 replicates x 2 runs/day x 20 days).
- LoB: 75 replicates of native samples.
- LoD: Five to nine serum samples containing low levels of Ferritin analyte, tested over five days with one run per day and nine replicates per run for each pack lot (resulting in ≥ 40 replicates minimally required for LoD estimation for each sample on each pack lot tested).
- LoQ: Eight to twelve serum samples containing low levels of Ferritin analyte, tested in replicates of nine per run with one run per day and five total days on each pack lot and instrument (resulting in a minimum of 40 replicates for each sample on each pack lot).
- Provenance for Precision, LoB, LoD, LoQ: Not specified, other than "native samples" or "serum samples."
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This device is an in-vitro diagnostic (IVD) immunoassay for quantitative determination of ferritin levels. Ground truth for such devices is typically established through reference methods or established laboratory gold standards rather than expert consensus on interpretive tasks. The document does not mention any involvement of human experts or radiologists in establishing ground truth for the test set performance evaluation. The "ground truth" here would be the actual ferritin concentration as determined by the predicate device (for method comparison) or highly controlled, characterized samples (for precision, linearity, limits).
4. Adjudication Method for the Test Set
Not applicable. As an IVD immunoassay, the "ground truth" or reference values are determined by laboratory measurements, not by human expert adjudication in the traditional sense (e.g., 2+1 for image interpretation).
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No. An MRMC study is relevant for diagnostic imaging or similar interpretive tasks involving multiple human readers. This document describes the performance evaluation of an automated immunoassay system, which does not involve human readers interpreting results in the same way.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes. The entire study describes the standalone performance of the Access Ferritin assay on the Dxl 9000 Access Immunoassay Analyzer. This is an automated system; the performance metrics (method comparison, precision, linearity, limits) are intrinsic to the assay and instrument combination without human intervention in the result generation or interpretation other than standard lab operating procedures.
7. The Type of Ground Truth Used
- Method Comparison: The "ground truth" or reference values for the method comparison study were obtained from the predicate device, the Access Ferritin assay run on the Access Immunoassay System (K926221/K052082).
- Precision, Linearity, LoB, LoD, LoQ: Ground truth for these studies was established using characterized samples (e.g., samples with known or carefully prepared concentrations, native low-level samples, or blank samples). These are standard practices in IVD analytical performance evaluation.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning or AI models. This is an immunoassay, not a device that uses AI models that require traditional training data. The development of the assay and its associated reagents/software would have involved internal R&D studies, but these are not described as a "training set" in the common AI sense.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as this is not an AI/ML device with a distinct "training set" as described in AI development. The "ground truth" for developing the assay itself would have involved extensive biochemical and analytical characterization in a laboratory setting.
§ 866.5340 Ferritin immunological test system.
(a)
Identification. A ferritin immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the ferritin (an iron-storing protein) in serum and other body fluids. Measurements of ferritin aid in the diagnosis of diseases affecting iron metabolism, such as hemochromatosis (iron overload) and iron deficiency amemia.(b)
Classification. Class II (performance standards).