(267 days)
VIDAS® AFP is an automated quantitative test for use on the VIDAS instruments for the quantitative measurement of alpha-fetoprotein (AFP) in human serum using the ELFA technique (Enzyme Linked Fluorescent Assay). The VIDAS AFP assay is indicated for the quantitative measurement of Alpha-Fetoprotein (AFP) in serum to aid in the management of patients with nonseminomatous testicular carcinoma.
The assay principle combines a one-step immunoassay sandwich method with a final fluorescent detection (ELFA). The Solid Phase Receptacle (SPR), a pipette tip-like device, serves as the solid phase as well as the pipetting device for the assay. The assay reagents are ready-to-use and pre-dispensed in the sealed reagent strips (STRs). All of the assay steps are performed automatically by the VIDAS instrument. The sample is transferred into the well containing AFP antibody (conjugate) labeled with alkaline phosphatase. The sample/conjugate mixture is cycled in and out of the SPR several times. This operation enables the antigen to bind with the immunoglobulins fixed to the interior wall of the SPR and to the conjugate to form a sandwich. Unbound compounds are eliminated during washing steps. Two detection steps are performed successively. During each step, the substrate (4-Methylumbeliferyl phosphate) is cycled in and out of the SPR. The conjugate enzyme catalyzes the hydrolysis of this substrate into a fluorescent product (4-Methyl-umbelliferone) the fluorescence of which is measured at 450 nm. The intensity of the fluorescence is proportional to the concentration of antigen present in the sample. At the end of the assay, results are automatically calculated by the VIDAS instrument in relation to two calibration curves corresponding to the two detection steps stored in memory, and then printed out.
Here's a breakdown of the acceptance criteria and study information for the VIDAS® AFP Assay, based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Acceptance Criteria (Implicit from Study Findings) | Reported Device Performance |
|---|---|---|
| Precision | Total variability (%CV) 400 IU/mL) up to 1/20. Linearity is 0.500 - 400.00 IU/mL. | |
| Clinical Equivalence to Predicate | Clinical trial results demonstrate agreement between the new device and the predicate device, as evidenced by regression analysis. | Passing and Bablok regression analysis of 253 samples showed a slope = 1.128 (95% CI: 1.115 to 1.143) and an intercept = -0.530 (95% CI: -0.658 to -0.416). |
Study Information:
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Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
- Clinical Trial Test Set: 257 samples were tested to compare the VIDAS® AFP and the TOSOH ST AIA-PACK AFP assays. 253 samples were used for the Passing and Bablok regression analysis.
- Data Provenance: Not explicitly stated. The nature of the samples for the clinical trial (e.g., patient samples) suggests retrospective or prospective testing, but the specific origin (e.g., country) is not mentioned.
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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)
- Not Applicable. For this in-vitro diagnostic device, ground truth for the clinical trial was established by comparison to a legally marketed predicate device (TOSOH ST AIA-PACK AFP assay), which itself serves as the reference standard in this context. There were no human expert readers establishing ground truth in the traditional sense for image interpretation or similar applications.
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Adjudication method (e.g. 2+1, 3+1, none) for the test set
- Not Applicable. As the ground truth was established by comparison to a predicate device's quantitative measurement, adjudication by multiple human experts is not relevant to this type of study.
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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
- No. This was not a MRMC comparative effectiveness study involving human readers and AI assistance. It is an in-vitro diagnostic device measuring a biomarker.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Yes, in essence. The VIDAS® AFP assay is an automated quantitative test. Its performance characteristics (precision, limits of detection, linearity, interference, hook effect) are evaluated as a standalone system. The "clinical trial" section compares its performance directly to another automated in-vitro diagnostic device (the predicate), essentially evaluating the algorithm/device's output without direct human interpretation influencing the final quantified result.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- For the clinical trial, the ground truth was established by comparison to a legally marketed predicate device (TOSOH ST AIA-PACK AFP assay). The predicate device's measurements served as the reference standard for evaluating the new device's quantitative agreement.
- For the precision, limits of detection, linearity, interference, and hook effect studies, the ground truth was based on the inherent characteristics of the samples used (e.g., known concentrations of AFP, spike/recovery studies), measured against the expected analytical performance.
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The sample size for the training set
- Not Applicable/Not provided. This submission describes an in-vitro diagnostic assay rather than a machine learning algorithm that typically undergoes distinct "training" with a labeled dataset. The device's calibration curves are "stored in memory," and for each kit lot and calibrator lot, there's a "master curve." This suggests a calibration process, not a machine learning training phase in the conventional sense.
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How the ground truth for the training set was established
- Not Applicable/Not provided. Similar to the above, there isn't a "training set" with ground truth in the context of a machine learning algorithm. The assay uses two calibration curves related to two detection steps, which are stored in memory. It also mentions a "Master curve for each kit lot and each calibrator lot are traceable to 1st IS 72/225 International Reference Preparation (IRP)". This traceability to an International Reference Preparation is how the assay's quantitative accuracy is established and maintained.
§ 866.6010 Tumor-associated antigen immunological test system.
(a)
Identification. A tumor-associated antigen immunological test system is a device that consists of reagents used to qualitatively or quantitatively measure, by immunochemical techniques, tumor-associated antigens in serum, plasma, urine, or other body fluids. This device is intended as an aid in monitoring patients for disease progress or response to therapy or for the detection of recurrent or residual disease.(b)
Classification. Class II (special controls). Tumor markers must comply with the following special controls: (1) A guidance document entitled “Guidance Document for the Submission of Tumor Associated Antigen Premarket Notifications (510(k)s) to FDA,” and (2) voluntary assay performance standards issued by the National Committee on Clinical Laboratory Standards.