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The Atellica™ CH Creatinine 2 (Crea 2) assay is for in vitro diagnostic use in the quantitative determination of creatinine in human serum, plasma (lithium heparin), and urine using the Atellica™ CH Analyzer, Such measurements are used in the diagnosis and treatment of renal diseases, and in monitoring renal dialysis.

The Atellica™ CH Chemistry Calibrator (CHEM CAL) is for in vitro diagnostic use in calibrating the Crea 2 assay using the Atellica™ CH Analyzer.

The Atellica CH Creatinine_2 (Crea_2) assay is based on the reaction of picric acid with creatinine in an alkaline medium as described in the original procedure of Jaffe. Creatinine reacts with picric acid in an alkaline medium to produce a red-colored creatinine-picrate complex. The rate of complex formation is measured at 505/571 nm and is proportional to the creatinine concentration. The Atellica CH Creatinine 2 (Crea_2) assay is a modification of the Jaffe method using rate blanking and intercept correction. Rate blanking is used to minimize bilirubin interference. Also, because nonspecific serum/plasma protein interactions with this reagent have been found to produce a positive bias of approximately 0.3 mg/dL (26.5 umol/L), serum/plasma measurements are automatically corrected by subtracting 0.3 mg/dL (26.5 umol/L) from each result.

The Atellica CH Chemistry Calibrator (CHEM CAL) is a 1 level lyophilized calibrator product prepared from bovine serum base product.

Here's an analysis of the provided text to extract the acceptance criteria and study details for the Atellica CH Creatinine 2 (Crea 2) and Atellica CH Chemistry Calibrator (CHEM CAL) devices:

1. Table of Acceptance Criteria and Reported Device Performance

Detailed Precision Results:

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

• Detection Limit (LoB/LoD):
  • LoB: 4 samples with no analyte, tested 5 times a day for 3 days (60 reps total).
  • LoD: 4 low analyte samples, tested 5 times a day for 3 days (60 reps total).
• Limit of Quantitation (LoQ):
  • Serum: 10 low samples, 5 replicates each, on 3 reagent lots for 3 days, 5 calibrations per day (75 measurements per reagent lot per sample). Total of 2250 determinations.
  • Urine: Similar setup for urine samples. Total of 2250 determinations.
• Linearity Study:
  • Serum/Plasma: 12 samples (high and low concentration mixes). 5 replicates measured for each sample.
  • Urine: 10 samples (high and low concentration mixes). 5 replicates measured for each sample.
• Precision Studies:
  • Controls, serum, and plasma pools: 80 replicates (n=2 replicates, 2 times a day for at least 20 days).
• Interferences:
  • "Fresh sample pools" containing low or high levels of creatinine in serum and urine. Specific count not given, but refers to testing across these pools.
• Method Comparison (Predicate):
  • Serum: 140 remnant de-identified samples.
  • Urine: 109 remnant de-identified samples.
  • Data Provenance: "Remnant de-identified samples" implies retrospective patient data. "No patient history information was obtained." The studies were conducted internally by Siemens Healthcare Diagnostic Inc. R&D personnel.
• Method Comparison (IDMS):
  • Serum: 49 samples.
• Matrix Equivalency:
  • 58 matched serum and lithium heparin plasma samples.

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

This type of device (Creatinine assay system) does not typically involve human expert adjudication for its ground truth. The "ground truth" for a chemical assay is established through highly accurate reference methods or certified reference materials.

• Ground Truth for Method Comparison: The predicate device, ADVIA Chemistry Enzymatic Creatinine_2 (ECRE_2), served as the comparative "ground truth" for the method comparison study. Additionally, "Isotope Dilution Mass Spectrometry (IDMS)" was used as a reference method for a subset of samples, which is a highly accurate and precise method for determining analyte concentrations and is recognized as a gold standard in clinical chemistry.
• Ground Truth for Calibration/Standardization: The device uses "IDMS Reference Method" for standardization, and the predicate uses "SRM967" (Standard Reference Material 967, which is a NIST standard for creatinine in human serum, often value-assigned by IDMS). These are highly precise and accurate methods, not typically involving human expert consensus in the same way an imaging device would.

4. Adjudication Method for the Test Set

Not applicable for this type of in-vitro diagnostic device. Ground truth is established by quantitative measurement or comparison to a reference method, not by expert adjudication of human interpretations.

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 is an in-vitro diagnostic device for quantitative chemical analysis, not an AI-assisted diagnostic imaging or interpretation device that would involve human readers.

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

The device itself is a standalone, automated analytical system (Atellica CH Analyzer) that performs the creatinine assay. The performance results reported (LoB, LoD, LoQ, Linearity, Precision, Interference, Method Comparison) represent the standalone performance of the assay on the analyzer. There is no human-in-the-loop component for the measurement of creatinine by this system.

7. The Type of Ground Truth Used

• Reference Methods:
  • The predicate device (ADVIA Chemistry Enzymatic Creatinine_2) was used as a reference for method comparison.
  • Isotope Dilution Mass Spectrometry (IDMS) was used as a highly accurate reference method for a subset of serum samples. This is considered a gold standard for creatinine measurement.
• Reference Materials: Standardization mentions "IDMS Reference Method," which implies traceability to primary reference materials. The predicate mentions SRM967, a certified reference material.
• Defined Protocols: CLSI (Clinical and Laboratory Standards Institute) protocols (EP17-A2, EP05-A3, EP06-A, EP7-A2, EP09-A3, EP28-A3c) were followed for various performance evaluations, which define how to establish performance characteristics against expected statistical and analytical metrics.

8. The Sample Size for the Training Set

Not explicitly mentioned in the provided text as a "training set" in the context of machine learning, which is typically what this question implies. For an IVD assay, method development and initial optimization would involve numerous experiments and samples, but these are typically not referred to as a "training set" in the AI sense. The text focuses on the validation studies performed to demonstrate performance.

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

As above, the concept of a "training set" with established ground truth as used in AI/ML is not directly applicable here. The development of an IVD assay involves extensive R&D, where analytical methods are refined to accurately measure the analyte. The "ground truth" during this development phase would be established by reference methods or gravimetric/volumetric preparations of known concentrations, similar to how the validation ground truth is established.

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