(78 days)
Diazyme Potassium Enzymatic Assay Kit in conjunction with Diazyme Potassium Low and High Calibrators, are intended for the quantitative determination of Potassium (K) in serum.
Potassium is determined spectrophotometrically through a kinetic coupling assay system using potassium dependent urea amidolyase (UAL). NADH generated in a coupling enzymatic reaction reduces a water soluble colorless tetrazolium salt, WST-1 in the presence of an electron mediator, 1-methoxy-5-methyl-phenazinium methyl sulfate (PMS), to form a water soluble formazan dye, which has a maximum absorbance at 450 nm. The corresponding increase of optical density at 450 nm is proportional to the potassium concentration in the serum. Diazyme's Potassium Enzymatic Assay is a two reagent (R1 and R2) based kinetic assay system. The results are obtained in 15 min by measuring absorbance at 450 nm. No off line pretreatment is needed. The assay has a wide measuring range from 2 to 8 mmol/L of serum potassium.
Here's an analysis of the acceptance criteria and study detailed in the provided 510(k) submission, formatted as requested:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implicitly derived from the comparison with the predicate device and the general understanding of what constitutes a "good correlation," "excellent precision," and "little interference" for an in vitro diagnostic device of this type. Specific numerical targets for correlation or precision are not explicitly stated as "acceptance criteria" but are demonstrated through the study results.
| Performance Metric | Acceptance Criteria (Implicit/Demonstrated) | Reported Device Performance |
|---|---|---|
| Correlation | Good correlation with predicate device | Correlation coefficient of 0.96 with Synchron LX I 725 Clinical System |
| Analytical Recovery | Expected recovery for spiked samples | 104% and 97% for potassium added to two different sera |
| Precision | Excellent precision | Data presented in an unreadable table, preventing extractable numerical values. |
| Interference | Little interference from common substances | Little interference at specified concentrations for NH4Cl, NaPi, CaCl2, NaCl, CuCl2, ZnCl2, FeCl3, Ascorbic Acid, Glucose, Bilirubin |
2. Sample Size for the Test Set and Data Provenance
- Test Set Sample Size: The document mentions "clinical patient serum samples" were used for comparison analysis but does not specify the exact number of samples in the test set.
- Data Provenance: The document does not explicitly state the country of origin of the data. It implies retrospective data as it refers to comparing results with a legally marketed predicate device on patient samples, but does not explicitly state if it was retrospective or prospective.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
This information is not provided in the document. For in vitro diagnostic assays measuring an analyte like potassium, the "ground truth" is typically established by the results from a recognized reference method or a legally marketed predicate device, as opposed to expert human interpretation.
4. Adjudication Method for the Test Set
This information is not applicable and therefore not provided. As explained in point 3, the "ground truth" for this type of device is an objective measurement rather than a subjective interpretation requiring adjudication among experts.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
An MRMC comparative effectiveness study was not conducted and is not applicable for this type of in vitro diagnostic device. This study design is typically used for imaging or diagnostic devices where human readers interpret results, and the AI assists in that interpretation. This device is an automated enzymatic assay.
6. Standalone Performance Study
Yes, a standalone performance study was done. The document describes several performance characteristics of the Diazyme Potassium Enzymatic Assay itself, including:
- Precision: Stated as "excellent precision" with a table (though unreadable).
- Measuring Range: 2 to 8 mmol/L.
- Analytical Recovery: Demonstrated with spiked samples.
- Interference Study: Tested against various common substances.
- Correlation: Compared to the predicate Synchron LX I 725 Clinical System using clinical patient serum samples.
This comprehensive characterization of the Diazyme device's performance, independently and in comparison to a predicate, constitutes a standalone performance study.
7. Type of Ground Truth Used
The ground truth for the test set (clinical patient serum samples) was established by comparison with a legally marketed predicate device (Synchron LX I 725 Clinical System), which itself would have been validated against established reference methods or clinical outcomes. The document also refers to a "comparison analysis" with the predicate, indicating the predicate's results served as the reference for evaluating the new device's accuracy.
8. Sample Size for the Training Set
The document does not provide information about a separate "training set" or its sample size. This is typical for an enzymatic assay, where the assay reagents and parameters are developed and optimized through laboratory work and internal validation rather than machine learning on a distinct training dataset.
9. How the Ground Truth for the Training Set Was Established
Since no distinct "training set" for an algorithm is mentioned or implied, the concept of establishing ground truth for a training set is not applicable. The "ground truth" in the development of such assays refers to the accurate measurement of potassium in known samples (e.g., calibrators, controls, or reference materials) that are used to develop and optimize the assay's chemical and enzymatic reactions and calibration curves.
§ 862.1600 Potassium test system.
(a)
Identification. A potassium test system is a device intended to measure potassium in serum, plasma, and urine. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels.(b)
Classification. Class II.