(214 days)
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
| Performance Metric | Acceptance Criteria (Implied by Predicate & Intended Use) | Reported Device Performance (DVT exclusion) |
|---|---|---|
| Sensitivity | High (critical for DVT/PE exclusion) | 100% (95% CI, 93.6-100.0) for suspected DVT (All PTPs) |
| Negative Predictive Value | High (critical for DVT/PE exclusion) | 100% (95% CI, 97.8-100.0) for suspected DVT (All PTPs) |
| Specificity | (No explicit threshold, but expected to be reasonable) | 32.9% (95% CI, 28.8-37.2) for suspected DVT (All PTPs) |
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.
§ 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).