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CRYOcheck Chromogenic Factor IX is for clinical laboratory use in the quantitative determination of factor IX activity in 3.2% citrated human plasma. It is intended to be used in identifying factor IX deficiency and as an aid in the management of hemophilia B in individuals aged 2 years and older. For in vitro diagnostic use.

CRYOcheck Chromogenic Factor IX is used for determination of FIX activity and contains the following four components, packaged in vials, and provided frozen to preserve the integrity of the components:
Reagent 1: Human FVIII, human FX, bovine FV and a fibrin polymerization inhibitor.
Reagent 2: Human FXIa, human FII, calcium chloride and phospholipids
Reagent 3: FXa Substrate containing EDTA and a thrombin inhibitor.
Diluent Buffer: Tris buffer solution containing 1% BSA and a heparin antagonist.

The provided text describes the performance of the CRYOcheck Chromogenic Factor IX device. Here's a breakdown of the acceptance criteria and the study that proves the device meets these criteria, based on the information provided:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria with pass/fail thresholds for each performance characteristic. Instead, it presents study results and concludes that the device performed effectively and demonstrates substantial equivalence. However, we can infer some criteria from the performance data presented.

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

• Multi-Reagent Lot Precision: 6 samples (1 normal reference control, 2 abnormal reference controls, 3 patient plasma samples).
• Multi-Reagent Lot Site to Site Reproducibility: 6 samples (1 normal reference control, 2 abnormal reference controls, 3 patient plasma samples).
• Linearity/Assay Reportable Range: 14 sample dilutions.
• Reference Interval: 128 normal, ostensibly healthy individuals.
• Shelf-Life Stability: Not specified, but likely involved multiple reference controls and patient plasma samples at each time point.
• In-Use Stability: Not specified, but involved multiple reference controls and patient plasma samples.
• Detection Limit (LoB): 4 blank plasma samples from individuals with severe congenital hemophilia B.
• Detection Limit (LoD): 4 plasma samples with low FIX activity from congenital hemophilia B donors.
• Detection Limit (LoQ): 4 plasma samples with low FIX activity from congenital hemophilia B donors.
• Interferences: Not specified, but likely involved spiked plasma samples.
• Recovery of FIX Replacements: Congenital FIX deficient plasma spiked with 7 FIX replacement therapies at 7 concentrations.
• Method Comparison Studies: 368 human plasma samples. These samples were from normal ostensibly healthy individuals, patients with von Willebrand disease, patients with congenital and acquired hemophilia A and B, and patients on recombinant factor IX treatments.
• Sample Integrity: 65 plasma samples.

Data Provenance: The document does not explicitly state the country of origin for the patient or donor samples. The studies involve both internal and external sites for reproducibility and method comparison. The mention of "congenital hemophilia B donors" and "patients with von Willebrand disease, and congenital and acquired hemophilia A and B" suggests the use of patient samples, implying a clinical or diagnostic context. The studies are retrospective in nature as they involve testing existing plasma samples.

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

For the studies described, the "ground truth" for Factor IX activity is established by:

• Reference controls: These are quality control materials with known or assigned values for FIX activity.
• Patient plasma samples: Their FIX activity is determined either by the device itself (for precision and reproducibility) or by a "comparator method" or "validated laboratory developed chromogenic factor IX assay" (for method comparison and LoQ studies).
• Spiked samples: For linearity, interference, and recovery studies, known amounts of FIX or interfering substances are added to samples to create a controlled "ground truth."
• Congenital FIX deficient plasma: For LoB, LoD, and recovery studies, plasma from individuals with a known severe deficiency serves as a baseline.

The document does not mention specific "experts" in the context of radiologists or similar roles establishing ground truth through consensus. Instead, the ground truth is based on:

• Established assay methods: The comparator method and the validated laboratory developed chromogenic factor IX assay are implicitly considered accurate for determining FIX activity. The qualifications of the personnel running these assays are not individually listed but are assumed to be trained laboratory professionals.
• Reference materials: Reference controls have assigned values.

4. Adjudication Method for the Test Set

The concept of an "adjudication method" (like 2+1 or 3+1) is typically relevant for studies where human expert interpretation is compared, e.g., in medical image analysis. In this context of an in vitro diagnostic device for quantitative determination in plasma, such an adjudication method is not described or applicable. The "ground truth" is based on the results of the reference methods, reference materials, and defined sample preparations.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This type of study is not relevant for an in vitro diagnostic device like the CRYOcheck Chromogenic Factor IX, which directly measures a biomarker rather than assisting human readers in interpreting complex data like medical images. The device itself is the "reader" providing a quantitative result.

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

Yes, the studies presented are all standalone (algorithm only) performance assessments for the CRYOcheck Chromogenic Factor IX device. The device itself performs the quantitative determination of factor IX activity. The results are generated by the instrument (IL ACL TOP Series or TOP 50 Series Instruments) based on the reagents and the plasma sample, without human interpretative input in the output. Human operators are involved in running the tests, but not in interpreting the quantitative output in a way that typical human-in-the-loop AI studies would assess.

7. The Type of Ground Truth Used

The ground truth used in these studies includes:

• Assigned values of reference controls: For precision and reproducibility.
• Results from a "comparator device" or "validated laboratory developed chromogenic factor IX assay": For method comparison and limit of quantitation. These are considered gold standards for FIX activity measurement.
• Known concentrations in spiked samples: For linearity, interference, and recovery studies.
• Known characteristics of congenital FIX deficient plasma: For detection limits and recovery studies.
• Plasma samples from "normal, ostensibly healthy individuals": For establishing reference intervals.

This primarily falls under the category of established assay methods and reference materials.

8. The Sample Size for the Training Set

The document does not mention a "training set" in the context of machine learning or AI. The CRYOcheck Chromogenic Factor IX is an in vitro diagnostic assay, not an AI/ML algorithm that requires training data. Its performance is based on chemical and enzymatic reactions, and its parameters are established through conventional analytical validation studies like those described.

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

As there is no "training set" in the AI/ML sense for this device, this question is not applicable. The device's operational parameters and performance are intrinsically defined by its design, chemical components, and the analytical validation tests presented.

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