(54 days)
For the quantitative determination of folate in serum or EDTA plasma and red blood cells using the Folate BA (Biotin Avidin) assay on the Chiron Diagnostics ACS: 180® Automated Chemiluminescence Systems.
The Chiron Diagnostics ACS:180 Folate assay is a competitive immunoassay using direct chemiluminescent technology. Folate in the patient sample competes with acridinium esterlabeled folate in the Lite Reagent for a limited amount of biotin-labeled folate binding protein. Biotin-labeled folate binding protein binds to avidin which is covalently coupled to paramagnetic particles in the Solid Phase. In the ACS:180 Folate assay the sample is pretreated to release the folate from endogenous binding proteins in the sample. The system performs the following steps for calibrators, quality control samples, and patient samples: dispenses 150 uL of sample into a cuvette, dispenses 50 µL of DTT, dispenses 100 µL of folate binding protein and 200 µL of Solid Phase and incubates for 5.0 minutes at 37°C, dispenses 100 µL of Lite Reagent and incubates for 2.5 minutes at 37°C, separates, aspirates, and washes the cuvettes with reagent water, dispenses 300 uL each of Reagent 1 and Reagent 2 to initiate the chemiluminescent reaction, reports results according to the selected option, as described in the system operating instructions or in the online help system. An inverse relationship exists between the amount of folate present in the patient sample and the amount of relative light units (RLUs) detected by the system.
Here's an analysis of the provided text, focusing on the acceptance criteria and the study details:
Device Name: Chiron Diagnostics ACS: 180 Folate Assay
Intended Use: For the quantitative determination of folate in serum or EDTA plasma and red blood cells using the Folate BA (Biotin Avidin) assay on the Chiron Diagnostics ACS:180® Automated Chemiluminescence Systems.
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state "acceptance criteria" with pass/fail thresholds. Instead, it presents "Performance Characteristics" which indicate the expected performance of a well-functioning assay. I will interpret these performance characteristics as the de-facto acceptance criteria for the device, given they are presented as a summary of safety and effectiveness.
| Performance Characteristic | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Sensitivity / Minimum Detectable Concentration | A minimum detectable concentration (lower limit of quantitation) should be established. | 0.25 ng/mL (0.6 nmol/L) |
| Assay Reportable Range | The assay should accurately measure folate concentrations up to a defined upper limit. | Up to 20 ng/mL (45.4 nmol/L) |
| Method Comparison (Serum) | A strong correlation (r) should exist with an alternate folate assay, with a slope close to 1 and intercept close to 0. | r = 0.95 |
| ACS:180 Folate = 0.92 (alternate chemiluminescent method) + 0.21 ng/mL | ||
| Method Comparison (RBC) | A strong correlation (r) should exist with an alternate folate assay, with a slope close to 1 and intercept close to 0. | r = 0.96 |
| ACS:180 RBC Folate = 0.93 (alternate chemiluminescent method) + 52.8 ng/mL | ||
| Precision (Within-run %CV) | Acceptable variability within a single run should be demonstrated across different folate concentrations. | 4.88% - 7.95% |
| Precision (Total %CV) | Acceptable total variability should be demonstrated across different folate concentrations, lots, runs, and systems. | 5.36% - 9.24% |
| Expected/Normal Range (Serum) | Reference ranges for normal and deficient populations should be established. | Normal: 4.25-23.8 ng/mL (9.65-54.0 nmol/L) |
| Deficient: 0.0-2.31 ng/mL (0.0-5.24 nmol/L) | ||
| Expected/Normal Range (RBC) | Reference ranges for normal and deficient populations should be established. | Normal: 322-886 ng/mL (731-2011 nmol/L) |
| Deficient: 9-157 ng/mL (20.4-356 nmol/L) |
2. Sample Size Used for the Test Set and Data Provenance
- Sensitivity/Analytical Sensitivity: 20 replicate determinations of the folate zero standard in 7 assays with 3 lots of reagents. (Total of 20 x 7 x 3 = 420 measurements, but focused on the zero standard.) The country of origin for this data is not specified, nor is whether it was retrospective or prospective, but it implies a controlled laboratory study.
- Method Comparison (Serum): 258 serum samples.
- Method Comparison (RBC): 189 red blood cell samples.
- Expected Results/Reference Range (Serum): 263 serum samples, described as "apparently healthy males and females".
- Expected Results/Reference Range (RBC): 109 red blood cell samples, described as "apparently healthy males and females".
- Precision: Four samples were assayed six times with three lots of reagents in 23 runs on four systems (n = 138 for each sample). (Total of 4 samples * 6 replicates * 23 runs = 552 sample measurements; or, 4 samples * 138 measurements per sample = 552 total measurements).
Data Provenance: The document states that "The data was obtained on apparently healthy males and females from the United States" for the Expected Results (reference ranges). For other sections (e.g., method comparison, precision, sensitivity), the country of origin and design (retrospective/prospective) are not explicitly stated but are implied to be from a controlled laboratory setting (likely prospective) given the nature of the tests.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not mention the use of experts to establish ground truth for the test set in the traditional sense of consensus or adjudication for diagnostic imaging studies.
However, for the deficient categories in the "Expected Results" table, the diagnosis was established based on "bone and/or peripheral blood smear pathology and other criteria including: megaloblastic anemia, folate deficient diet, malabsorption, alcoholism, Tropical Sprue, abnormal blood parameters including mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and hematocrit (HCT)." While this indicates a clinical diagnosis process, it doesn't specify if a panel of experts was used or their qualifications for this specific study. It implies standard diagnostic practices were followed.
4. Adjudication Method for the Test Set
No explicit adjudication method (e.g., 2+1, 3+1) is mentioned for any of the studies described. The ground truth for deficient samples appears to rely on a set of clinical and pathological criteria rather than expert consensus on individual cases specifically for the study.
5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done
No. This document describes the performance characteristics of an in vitro diagnostic (IVD) assay (a lab test), not an AI-assisted diagnostic imaging device. Therefore, a multi-reader, multi-case (MRMC) comparative effectiveness study with human readers improving with AI vs without AI assistance is not applicable and was not performed.
6. If a Standalone (i.e. algorithm only, without human-in-the-loop performance) Was Done
Yes, this is a standalone performance study. The document details the analytical performance of the ACS:180 Folate assay system (an automated chemiluminescence system) itself, independent of human interpretation of its results. The reported metrics (sensitivity, reportable range, method comparison, precision, expected ranges) are all inherent to the device's function.
7. The Type of Ground Truth Used
- Analytical Sensitivity, Reportable Range, Precision: Ground truth is established by the known concentrations of calibrated standards and controls used in the assay.
- Method Comparison: Ground truth is functionally established by an "alternate chemiluminescent method" (the predicate or another established assay), rather than an absolute gold standard. The aim is to show agreement with an existing method.
- Expected Results (Normal/Deficient Ranges):
- Normal: Derived from samples obtained from "apparently healthy males and females". The assumption is that these individuals represent a "normal" folate status.
- Deficient: Diagnosed by "bone and/or peripheral blood smear pathology and other criteria including: megaloblastic anemia, folate deficient diet, malabsorption, alcoholism, Tropical Sprue, abnormal blood parameters including mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and hematocrit (HCT)." This is clinical diagnostic ground truth.
8. The Sample Size for the Training Set
The document does not describe a "training set" as it would for a machine learning algorithm. This is a conventional IVD assay, not an AI/ML-based device in the modern sense. The "training" in this context would refer to internal development and optimization by the manufacturer, for which sample sizes are not typically reported in such summaries.
9. How the Ground Truth for the Training Set Was Established
As stated above, the concept of a "training set" and its associated ground truth establishment is not relevant in the context of this traditional IVD assay and its regulatory submission. The device's performance is characterized against known analytical standards and clinical classifications, not by 'learning' from a labeled dataset.
§ 862.1295 Folic acid test system.
(a)
Identification. A folic acid test system is a device intended to measure the vitamin folic acid in plasma and serum. Folic acid measurements are used in the diagnosis and treatment of megaloblastic anemia, which is characterized by the presence of megaloblasts (an abnormal red blood cell series) in the bone marrow.(b)
Classification. Class II.