Search Results

VIDAS® D-Dimer New is an automated, quantitative test for use on the VIDAS analyzer for the immunoenzymatic determination of cross-linked fibrin degradation products (FbDP) containing the D-dimer domain in citrated human plasma using the Enzyme Linked Fluorescent Assay (ELFA) technique. VIDAS D-Dimer New is indicated for use in conjunction with a clinical pretest probability (PTP) assessment model to exclude deep vein thrombosis (DVT) and pulmonary embolism (PE) in outpatients suspected of DVT or PE.

The VIDAS® D-Dimer New (DD2) Assay is an automated quantitative test for use on the VIDAS instrument (K891385) for the immunoenzymatic determination of fibrin degradation products (FbDP) in human plasma using the enzyme-linked fluorescent immunoassay (ELFA) technique. The instrument controls all assay steps and assay temperatures. A pipette tip-like disposable device, the Solid Phase Receptacle (SPR), serves as the solid phase as well as a pipettor for the assay. Reagents for the assay are ready-to-use and pre-dispensed in the sealed DD2 Reagent Strips.

Here's a breakdown of the acceptance criteria and study details for the VIDAS D-Dimer New (DD2) Assay, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The acceptance criteria are not explicitly stated as numerical thresholds in the provided text. However, for a diagnostic test intended to exclude DVT and PE, very high sensitivity and negative predictive value are paramount to ensure that patients with the condition are not missed. The study results demonstrate 100% sensitivity and 100% negative predictive value, which would be considered excellent performance for this intended use.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size:
  • Pulmonary Embolism (PE) / Deep Venous Thrombosis (DVT) Study: 302 patients (initial study mentioned)
  • Deep Vein Thrombosis (DVT) Exclusion Study: 555 patients (after one sample excluded due to volume limitations from an initial 556)
• Data Provenance: Retrospective for the PE/DVT study (frozen samples) and prospective for the DVT exclusion study. The text does not specify the country of origin, but it mentions a "multi-center, prospective cohort study" and "three hospitals," suggesting multiple sites, likely within the same country where the submission was made (US, given the FDA filing).

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The text does not provide information on the number or qualifications of experts used to establish the ground truth for the test set.

4. Adjudication Method for the Test Set

The text does not explicitly describe an adjudication method for establishing ground truth for the test set. The DVT exclusion study mentions "clinical outcome of the patients" and "serial compression ultrasound (CUS)" for patients with positive D-dimer/high PTP, implying a diagnostic workup to confirm or rule out DVT, but no specific adjudication panel or method (e.g., 2+1) is detailed.

5. 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

A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The device is an automated quantitative assay for D-Dimer, not an AI-assisted imaging device or a system that requires human interpretation in the same way. Therefore, the concept of human readers improving with/without AI assistance does not apply here.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done

Yes, a standalone study was done. The VIDAS D-Dimer New assay is an "automated quantitative test" and "performed without knowledge of the PTP assessment results and the clinical outcome of the patients." This indicates that the device's performance was evaluated purely on its own diagnostic output (D-dimer levels) against the clinical ground truth. The "human-in-the-loop" aspect comes from the intended use, where the D-Dimer result is used in conjunction with a clinical PTP model for decision-making, but the assay itself is standalone.

7. The Type of Ground Truth Used

The ground truth for the test sets was based on clinical diagnosis/outcomes data.

• For the PE/DVT study, "frequency of venous thromboembolic disease" was determined.
• For the DVT exclusion study, patients "underwent no further diagnostic testing and were followed up for 3 months for development of DVT" if negative D-dimer and low/moderate PTP. Patients with positive D-dimer and/or high PTP "underwent serial compression ultrasound (CUS)." This implies that the presence or absence of DVT was confirmed or ruled out through standard clinical diagnostic methods and follow-up, which serves as the ground truth.

8. The Sample Size for the Training Set

The text does not specify a separate training set or its sample size. This is common for traditional laboratory assays where the "training" involves assay development and optimization, rather than a machine learning training phase on a distinct dataset. The performance data presented is likely from validation studies.

9. How the Ground Truth for the Training Set Was Established

Since a distinct "training set" in the context of machine learning is not mentioned, the method for establishing its ground truth is not applicable/not provided in this document. The ground truth for the validation/performance studies was established via clinical diagnosis and follow-up, as described in point 7.

Ask a specific question about this device

The VIDAS® D-Dimer New assay is intended for use as an aid in the diagnosis of deep venous thrombosis and pulmonary embolism disease.

The VIDAS® D-Dimer New (DD2) Assay is an automated quantitative test for use on the VIDAS instrument (K891385) for the immunoenzymatic determination of fibrin degradation products (FbDP) in human plasma using the enzyme-linked fluorescent immunoassay (ELFA) technique. The instrument controls all assay steps and assay temperatures. A pipette tip-like disposable device, the Solid Phase Receptacle (SPR), serves as the solid phase as well as a pipettor for the assay. Reagents for the assay are ready-to-use and pre-dispensed in the sealed DD2 Reagent Strips.

The assay principle combines a two-step enzyme immunoassay sandwich method with a final fluorescent detection (ELFA). The Solid Phase Receptacle (SPR) serves as the solid phase with the anti-FbDP monoclonal (mouse) antibodies P10B5E12C9 adsorbed on its surface, as well as the pipetting device for the assay.

The instrument performs all of the assay steps automatically. The reaction medium is cycled in and out of the SPR several times according to a specified protocol.

The sample is taken and transferred into the well containing the conjugate, which is an alkaline phosphatase-labeled anti-FbDP monoclonal (mouse) antibodies (P2C5A10) The sample/conjugate mixture is cycled in and out of the SPR several times to increase the reaction speed. The antigen binds to antibodies coated on the SPR and to the conjugate forming a "sandwich".

In the second step, the remaining free antigen sites are saturated by cycling the conjugate in the fifth well of the strip in and out of the SPR. Unbound components are eliminated during the washing steps.

Two detection steps are then performed successively. During each step, the substrate (4-Methyl-umbelliferyl phosphate) is cycled in and out of the SPR. The conjugate enzyme catalyzes the hydrolysis of this substrate into a fluorescent product (4-Methylumbelliferone), 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 VIDAS in relation to two calibration curves stored in memory corresponding to the two detection steps. A threshold signal determines the choice of the calibration curve to be used for each sample. The results are then printed out.

The acceptance criteria and study proving the device meets them are outlined below:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state quantitative acceptance criteria for each metric (Sensitivity, Specificity, Negative Predictive Value) prior to presenting results. Instead, it demonstrates the performance of the new DD2 Assay in comparison to the predicate DD Assay. The implicit acceptance criteria appear to be substantial equivalence or improvement over the predicate device.

Ask a specific question about this device