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The intended use for the N-ASSAY CPK-L Reagent is for the quantitative determination of serum creatine phosphokinase (CPK) activity in human serum in the diagnosis and treatment of myocardial infarction and muscle diseases such as muscular dystrophy.

The N-ASSAY CPK-L reagent is based on an optimized CPK kinetic method as recommended by the Japan Society of Clinical Chemistry, shows good correlation with similar CPK reagents, practically no interference by coexistent substances, high sensitivity with good reproducibility, wide assay range, and is convenient ready-to-use liquid type reagent. The N-ASSAY CPK-L reagent utilizes an enzymatic method. In this procedure, creatine phosphate is dephosphorylated by creatine phosphokinase (CPK) in the presence of adenosine disphosphate (ADP) to produce creatine and adenosine triphosphate (ATP). ATP is dephosphorylated by hexokinase in the presence of D-glucose to produce glucose-6-phosphate (G-6-P) and adenosine diphosphate. Glucose-6-phosphate dehydrogenase specifically oxidizes G-6-P to 6-phosphogluconate with the concurrent reduction of nicotinamide adenine dinucleotide phosphate (NADP) to nicotinamide adenine dinucleotide phosphate reduced (NADPH). The NADPH produced absorbs light at 340 nm (main) and 405 (sub) and can be detected spectrophotometrically. The increase per minute in absorbance measured at 340 nm (main) and 405 (sub), due to the formation of NADPH, is directly proportional to CPK activity in the sample.

Here's an analysis of the provided text regarding the acceptance criteria and study for the CRESTAT N-ASSAY CPK-L Reagent:

Acceptance Criteria and Device Performance

The provided document describes the safety and effectiveness of the N-ASSAY CPK-L Reagent in relation to a predicate device, the Medical Analysis Systems CK liquid reagent (K781719). The acceptance criteria for this type of medical device are generally framed around demonstrating substantial equivalence to a legally marketed predicate device.

Table of Acceptance Criteria and Reported Device Performance

Study Details

The information provided describes a comparison study to demonstrate substantial equivalence to a predicate device.

1. Sample size used for the test set and the data provenance:

   • Sample Size: The document mentions "serum samples" but does not specify the exact number of samples used in the comparison study.
   • Data Provenance: The document does not specify the country of origin of the data. It does not explicitly state if the study was retrospective or prospective, but comparison studies for K510 submissions often involve collecting prospective samples or using banked samples.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • This type of study (comparing a new in-vitro diagnostic reagent against a predicate reagent) does not typically involve human expert adjudication for image interpretation. The "ground truth" is established by the performance of the predicate device. Therefore, no information is provided on experts or their qualifications for establishing ground truth in this context.

3. Adjudication method for the test set:

   • Not applicable as this is a comparison study between two in-vitro diagnostic reagents, not an interpretation task requiring expert adjudication.

4. 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:

   • No. This is not an AI-assisted diagnostic device, nor does it involve human readers interpreting cases. It is an in-vitro diagnostic reagent.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Yes, implicitly. The performance metrics (correlation, regression, minimum detectable level, linearity, precision) are all derived from the performance of the reagent itself, a "standalone algorithm" in the context of an in-vitro diagnostic. There is no human-in-the-loop component for the measurement itself; the human only performs the assay.

6. The type of ground truth used:

   • The "ground truth" in this context is the results obtained from the predicate device (Medical Analysis Systems CK liquid reagent, K781719). The study seeks to show that the new device's results are substantially equivalent to those of the predicate.

7. The sample size for the training set:

   • The document does not explicitly describe a "training set" in the sense of modern machine learning. For an in-vitro diagnostic reagent, the "training" involves the development and optimization of the reagent formulation and assay parameters based on known chemical principles and experimental trials. The specific sample size for this development phase is not provided.

8. How the ground truth for the training set was established:

   • Not directly applicable in the sense of a medical imaging or AI model "training set." The "ground truth" during the development of this chemical reagent would have been established through well-characterized reference materials, known concentrations of CPK, and established laboratory methods to ensure the reagent's components and reactions are functioning as expected to accurately measure CPK activity.

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