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ENVOY®500 CK REAGENT KIT is intended for the quantitative in vitro determination of creatine kinase (CK) in buman serum and plasma using the ENVOY 500 Chemistry System.

It is not intended for use in Point of Care settings.

Creatine phosphokinase and its isoenzymes measurements are used in the diagnosis and treatment of myocardial infarction and muscle diseases such as progressive, Duchenne-type muscular dystrophy.

ENVOY CK REAGENT KIT is available as kit only. It consists of a bi-reagent R1 and R2 whose composition,

for R1: 125 mmol/L Imidazole buffer, pH 6.10; 25 mmol/L D-Glucose; 25 mmol/L N-Acetyl-L-Cysteine; 12.5 mmol/L Magnesium acetate; 2.4 mmol/L NADP; 2.0 mmol/L EDTA; > 6800 U/L Hexokinase (microorganism);

This document describes the performance characteristics and acceptance criteria for the ENVOY 500 CK REAGENT KIT, an in vitro diagnostic device for the quantitative determination of creatine kinase (CK) in human serum and plasma.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Precision Test Set: 80 measurements for each of 3 levels of samples (Level 1, Level 2, Level 3). Each level was measured two times per run, for two runs per day, for twenty operating days, on two instruments.
• Linearity Test Set: 11 levels of patient pools (for serum).
• Detection Limit Test Set: 15 measurements of 4 samples for LoD; 15 measurements of 4 samples for LoQ.
• Interference Test Set: For each potential interferent, 2 serum sample pools (a low activity pool at 150 U/L and a high activity pool at 1200 U/L) were used. Aliquots of each pool were spiked with increasing interferent concentrations (e.g., 9 concentrations for triglycerides, 7 for unconjugated bilirubin, etc.). Each point was measured in triplicate per run.
• Method Comparison (Serum) Test Set: 100 serum patient samples.
• Method Comparison (Lithium Heparin Plasma) Test Set: 40 plasma specimens (in lithium heparin).
• On Board Stability Test Set: At least 3 levels of sample (high/medium/low) were tested in duplicate at Day 0, and 4 activity levels were analyzed in duplicate for at least 30 days.

Data Provenance: The document does not explicitly state the country of origin for the patient samples or if the data was retrospective or prospective. Given the submitter is ELITech Clinical Systems SAS, France, and the testing was conducted for regulatory submission in the US, it is plausible the studies were conducted in Europe or at contract research organizations. The nature of the studies (e.g., precision, linearity, interference, method comparison) generally involves prospective collection or commercially available control/patient samples for analytical validation.

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

This document describes the analytical performance of an in-vitro diagnostic reagent kit (ENVOY 500 CK REAGENT KIT). For such devices, "ground truth" generally refers to reference methods or measurements by highly calibrated instruments, not expert human interpretation. Therefore, the concept of "number of experts used to establish ground truth" and their qualifications is not applicable in this context. The ground truth for analytical studies is established by:

• Reference materials or calibrators traceable to international standards (e.g., IFCC method for CK).
• Predicate devices or established methods for method comparison studies.
• Precise gravimetric or volumetric preparations for linearity and spiking studies.

4. Adjudication Method for the Test Set

The concept of an "adjudication method" (e.g., 2+1, 3+1) is typically relevant for studies involving subjective human interpretation of diagnostic images or data, where discrepancies between readers need to be resolved to establish ground truth for algorithm training or testing.

For the analytical performance studies described for the ENVOY 500 CK Reagent Kit, no such adjudication method was used or is applicable. The measurements are quantitative and objective, following established laboratory protocols and guidelines (e.g., CLSI protocols). Discrepancies would be resolved through re-testing, investigation of instrument or reagent issues, or statistical analysis (e.g., outliers).

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

Not applicable. This document describes an in-vitro diagnostic reagent kit, not an AI-based diagnostic device intended for human reader assistance. Therefore, no MRMC comparative effectiveness study involving human readers or AI assistance was performed.

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

This document describes the performance of an in-vitro diagnostic reagent kit that functions on a chemistry analyzer (Envoy 500 Chemistry System). The device itself is the reagent kit, which works in conjunction with the instrument to provide quantitative results. It is not an algorithm or AI-based device. The performance described is inherently "standalone" in the sense that it measures the analytical capability of the reagent-instrument system to quantify CK levels without human intervention in the measurement process itself, beyond sample loading and system operation. No human-in-the-loop performance is relevant for the analytical measurement part of the device's function.

7. The Type of Ground Truth Used

The ground truth for the various analytical performance characteristics was established using:

• Reference Methods/Standards: For traceability, the calibration factor for the ENVOY 500 CK Reagent Kit has traceability to the IFCC method (International Federation of Clinical Chemistry and Laboratory Medicine) recommendations for CK activity determination.
• Predicate Device Comparison: For method comparison, the predicate device (ELITech Clinical Systems CK NAC SL on Selectra ProM analyzer) served as the reference for comparison using patient samples.
• Prepared Samples/Known Concentrations:
  • For linearity, patient pools were prepared by spiking a serum pool and dilution to obtain 11 levels with equidistant activities (known relative concentrations).
  • For detection and quantification limits, samples were prepared by diluting patient samples to obtain specific activities (e.g., approximately 3.5 U/L for LoD, 5 U/L for LoQ).
  • For interference, serum sample pools were spiked with increasing concentrations of known interferents against control samples.
• Statistical Analysis: Precision studies rely on repeated measurements to quantify variability, with "ground truth" derived from the calculated mean and statistical metrics.

In summary, the ground truth is primarily based on reference methods (IFCC), comparison to a legally marketed predicate device, and precisely prepared samples with known (or highly characterized) concentrations/activities.

8. The Sample Size for the Training Set

Not applicable. This device is an in-vitro diagnostic reagent kit, not a machine learning or artificial intelligence-based device that requires a "training set" in the conventional sense. The "training" of such a system involves chemical formulation, optimization of reaction conditions, and calibration procedures using calibrators or reference materials.

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

Not applicable. As stated above, this device does not utilize a "training set" in the context of machine learning. The "ground truth" for developing and optimizing the reagent kit and its associated methods would involve:

• Chemical principles and stoichiometry: The understanding of the enzyme kinetics and chemical reactions being measured (e.g., the IFCC recommended method for CK).
• Reference materials and calibrators: Used to ensure accuracy and traceability of the quantitative measurements.
• Experimental optimization: Through iterative testing and modification of reagent concentrations, pH, and reaction conditions to achieve optimal performance characteristics (sensitivity, specificity, stability, etc.).

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