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Binding assay for the in vitro quantitative determination of folate in human serum. The binding assay is intended for use on Elecsys and cobas e immunoassay analyzers. Folic acid measurements are used in the diagnosis and treatment of anemias.

The Folate III Assay employs a competitive test principle using natural folate binding protein (FBP) specific for folate. Folate in the sample competes with the added folate (labeled with biotin) for the binding sites on FBP (labeled with a ruthenium complex). Results are determined using a calibration curve that is generated specifically on each instrument by a 2 point calibration and a master curve (5-point-calibration) provided with the reagent bar code.

Roche Diagnostics' Elecsys Folate III Assay is a quantitative in vitro diagnostic device designed for measuring folate levels in human serum, primarily for the diagnosis and treatment of anemias. The following outlines its acceptance criteria and the studies performed to demonstrate its performance.

Acceptance Criteria and Reported Device Performance

The acceptance criteria for the Elecsys Folate III Assay are primarily established through comparison to a predicate device, the Roche Elecsys Folate III (K082340). The device demonstrates comparable or improved analytical performance characteristics.

Study Details

The provided document describes a premarket notification (510(k)) to demonstrate substantial equivalence to a legally marketed predicate device (Roche Elecsys Folate III, K082340). The studies conducted are analytical performance studies.

1. Sample sizes used for the test set and the data provenance:

   • Precision (Repeatability/Intermediate): Human serum (HS) samples (5 levels) and PreciControl Varia (PCV) control levels (2 levels) were used. The document lists mean, SD, and CV values, which are derived from repeated measurements of these samples. The exact number of individual patient samples in the precision study is not explicitly stated, but typically these studies involve multiple runs over several days.
   • Analytical Specificity (Cross-reactivity): Specific cross-reactants (Amethopterin, Aminopterin, Folonic acid) were tested at concentrations of 1500 ng/mL.
   • Limitations (Interference): Bilirubin (< 29 mg/dL), Lipemia (< 1500 mg/dL), Biotin (< 21 ng/mL), Rheumatoid factors (< 1000 IU/mL), IgG (< 1.6 g/dL), IgM (< 1.0 g/dL), IgA (< 0.4 g/dL) were tested. Also, 16 commonly used pharmaceuticals and human erythropoietin were tested. The number of samples for each interference test is not specified.
   • Reference Range Study:
     • Predicate Device: N = 261 subjects from USA.
     • Candidate Device: N = 214 subjects from USA.
     • Provenance: All reference range data is from the USA. These appear to be prospective studies to establish healthy reference ranges.
   • Method Comparison: n = 106 patient samples were used, with folate concentrations ranging from 2.08 ng/mL to 19.6 ng/mL.
     • Provenance: Not explicitly stated, but typically these are retrospective or prospectively collected clinical samples.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):
   This is an in vitro diagnostic (IVD) device for quantitative measurement of an analyte (folate). "Ground truth" in this context refers to the concentration of folate in the samples, determined by a reference method or the predicate device, rather than expert interpretation of images or clinical outcomes. Therefore, no "experts" in the sense of medical specialists reviewing results are mentioned as establishing ground truth. The ground truth for method comparison is the result obtained from the predicate device (Abbott Architect Folate assay, K092740).

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:
   Not applicable, as this is an IVD device for quantitative measurement, not an assessment of diagnostic performance based on human interpretation or consensus.

4. 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 is an IVD device, not an AI-assisted diagnostic imaging device that involves human readers.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
   Yes, the performance characteristics (e.g., precision, measuring range, analytical sensitivity, specificity) described are for the Elecsys Folate III Assay itself, operating as a standalone algorithm/device. The method comparison study directly compares the results of the candidate device with another established assay.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • Analytical Performance: The ground truth for evaluating analytical performance parameters like LoB, LoD, LoQ, precision, and specificity is typically based on control materials, spiked samples, and established analytical methods.
   • Method Comparison: The ground truth for the method comparison study was the results obtained from the predicate device, the Abbott Architect Folate assay (K092740). The acceptance criteria for this comparison would be for the candidate device's results to closely agree with those of the predicate.
   • Reference Range: The reference range was established by testing samples from a healthy population in the USA (N=214).

7. The sample size for the training set:
   The document does not specify a "training set" in the context of statistical modeling or machine learning. This is an immunoassay device, and its calibration curve is generated using a "2 point calibration and a master curve (5-point-calibration) provided with the reagent bar code" (page 3). The master curve is based on internal validation data, but a specific "training set sample size" for model development is not provided.

8. How the ground truth for the training set was established:
   As above, the concept of a "training set" with established ground truth as in machine learning is not directly applicable to this immunoassay. The device's operational characteristics and performance are based on analytical validation following established guidelines (CLSI documents EP5-A2, EP17-A2, EP6-A, EP-09-A2-IR mentioned on page 12). The calibration curve, which is critical to the assay's function, is standardized with a master curve and a 2-point calibration, and the device is standardized against the WHO International Standard NIBSC code: 03/178 (page 7).

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