(154 days)
The VIDAS D-Dimer (DD) Assay is for the quantitative detection of fibrin degradation products (FbDP) in human plasma. It is intended to aid in the diagnosis of deep venous thrombosis and pulmonary embolism disease.
The VIDAS D-Dimer (DD) assay is intended for use with a VIDAS (Vitek ImmunoDiagnostic Assay System) instrument as an automated quantitative enzyme-linked fluorescent immunoassay (ELFA) for the determination of fibrin degradation products (FbDP) in plasma (trisodium citrate). The VIDAS D-Dimer assay is intended for use as an aid in the diagnosis of deep venous thrombosis and pulmonary embolism disease.
The VIDAS D-Dimer assay is an enzyme-linked fluorescent immunoassay (ELFA) performed on an automated VIDAS instrument. All assay steps and assay temperature are controlled by the instrument.
A pipette tip-like disposable device known as the Solid Phase Receptacle (SPR), serves as a solid phase for the assay as well as a pipetting device. Reagents for the assay are located in the sealed VIDAS DD Reagent Strips.
The VIDAS D-Dimer kit contains 60 SPRs, 60 Reagent Strips, 2 Bottles of Calibrator, 2 Bottles each level of Positive Control (three levels) and 1 bottle of Diluent. The Kit contains a sufficient number of SPR's and Strips to perform 60 Tests.
The SPR is coated with mouse anti-FbDP antibodies. The Strip contains the reagents necessary to perform the assay, as well as a sample well for placement of the specimen. Each DD test requires one DD Reagent Strip and one DD SPR.
Here's a breakdown of the acceptance criteria and study information for the VIDAS D-Dimer (DD) Assay, based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Specific Criteria/Metric | Reported Device Performance |
|---|---|---|
| Correlation | Comparison with predicate device (American Bioproducts Asserachrom D-Di Kit) | Line equation: y = 1.06x - 50.4. Correlation coefficient: 0.90. |
| Sensitivity (Analytical) | Lowest measurable level of FbDP (limit of detection) at 95% probability | 45 ng/ml. The assay is designed to measure FbDP between 45 ng/ml and 1000 ng/ml. |
| Specificity | Cross-reactivity with fibrinogen and its degradation products | Two monoclonal antibodies used in combination recognized D-Dimer and D-Dimer containing fibrin derivatives, and did not cross-react with fibrinogen or its degradation products. (Individual antibodies showed weak cross-reaction with fibrinogen degradation products, but this was overcome in combination). |
| Interfering Substances | Interference from hemolyzed, icteric, or lipemic specimens | No assay interference was demonstrated when testing spiked hemolyzed, icteric, or lipemic specimens. (However, use of such samples is not recommended). |
| Precision/Reproducibility | Intra-assay precision (Coefficients of Variation - CV) | Ranged from 3.8% to 5.8% over the reportable range of the assay. |
| Inter-assay reproducibility (CV over 8 weeks) | Did not exceed 7.6%. | |
| Inter-assay, inter-instrument reproducibility (CV for 4 samples across 8 runs on 8 instruments) | Did not exceed 4.9%. | |
| Calibrator Validity | Master curve validity for the kit's shelf life | The calibrator in the kit ensures the master curve stored by the VIDAS instrument is valid. The body of data supports the use of a single calibrator for this purpose. |
Study Details
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Sample size used for the test set and the data provenance:
- Test Set Sample Size: The document does not explicitly state the sample size used for the test set. It mentions "body of data" for calibrator validity and "four different serum samples in 8 runs on 8 different instruments" for inter-instrument reproducibility, but a comprehensive sample size for all performance metrics is not provided.
- Data Provenance: Not explicitly stated. The document describes laboratory performance characteristics, which would typically involve controlled laboratory settings. There is no information regarding country of origin or whether the data was retrospective or prospective.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- This information is not provided in the document. The document describes analytical performance characteristics of an immunoassay, not a diagnostic interpretation that would typically require expert ground truth establishment. The "ground truth" here is the actual concentration of FbDP, as measured by reference methods or spiked samples.
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Adjudication method for the test set:
- Not applicable/Not mentioned. Adjudication methods like 2+1 or 3+1 are typically used in studies involving human interpretation or clinical endpoint assessments, which are not the focus of this analytical performance 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 is an analytical performance study for an automated immunoassay. It does not involve human readers interpreting results, nor does it involve AI assistance for human interpretation.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes. This study exclusively details the performance of the VIDAS D-Dimer assay performed on an automated VIDAS instrument. The device itself is an automated system providing quantitative results without human interpretation of the primary measurement.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The ground truth for the analytical performance studies appears to be based on:
- Reference measurements/Predicate device comparison: For correlation, the predicate device (American Bioproducts Asserachrom D-Di Kit) served as a reference.
- Known concentrations: For sensitivity, specificity, and interfering substances, components were likely tested at known, purified, or spiked concentrations (e.g., purified fibrinogen degradation products, spiked hemolyzed specimens).
- Statistical analysis of repeated measurements: For precision and reproducibility.
- It is not based on expert consensus, pathology, or outcomes data, as these are typically relevant for clinical diagnostic studies, not analytical assay validation.
- The ground truth for the analytical performance studies appears to be based on:
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The sample size for the training set:
- Not applicable/Not mentioned. This is an immunoassay, not a machine learning algorithm that typically requires a distinct "training set." The assay development and calibration would involve its own internal validation, but it's not described in terms of a "training set" in the context of AI/ML.
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How the ground truth for the training set was established:
- Not applicable/Not mentioned. As this is not an AI/ML algorithm requiring a training set with established ground truth in the conventional sense, this information is not relevant to the provided text.
§ 864.7320 Fibrinogen/fibrin degradation products assay.
(a)
Identification. A fibrinogen/fibrin degradation products assay is a device used to detect and measure fibrinogen degradation products and fibrin degradation products (protein fragments produced by the enzymatic action of plasmin on fibrinogen and fibrin) as an aid in detecting the presence and degree of intravascular coagulation and fibrinolysis (the dissolution of the fibrin in a blood clot) and in monitoring therapy for disseminated intravascular coagulation (nonlocalized clotting in the blood vessels).(b)
Classification. Class II (performance standards).