(56 days)
Diazyme Sodium Enzymatic Assay Kit in conjunction with Diazyme Sodium Low and High Calibrators, are intended for the quantitative determination of sodium (NA) in serum.
Diazyme's Sodium Enzymatic assay is proven to be equivalent to ISE method but more user friendly in automated analyzers. Sodium is determined enzymatically via sodium dependent ß-galactosidase activity with ONPG as substrate. The absorbance at 405 nm of the product O-nitrophenyl is proportional to the sodium concentration.
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Acceptance Criteria and Study Details for Diazyme Sodium Enzymatic Assay
This submission focuses on establishing substantial equivalence to a predicate device rather than defining specific performance acceptance criteria against a clinical gold standard. The criteria are largely based on analytical performance compared to an established method.
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Correlation with Predicate Method (ISE) | High correlation coefficient (e.g., >0.95 or similar to predicate) | 0.96 |
| Precision (CV%) | Low coefficient of variation (indicating reproducibility) | Within Precision: 144mM Na+: 3.2%; 164mM Na+: 3.0% |
| Total Precision: 144mM Na+: 5.3%; 164mM Na+: 3.3% | ||
| Analytical Recovery | Recoveries close to 100% (indicating accuracy) | 104% and 97% (for sodium added to two different sera) |
| Interference | Minimal or no significant interference from common substances | Little interference found at indicated concentrations for various substances (NH4Cl, NaPi, CaCl2, NaCl, etc.) |
| Measuring Range | Broad enough for clinical utility | 80 to 180 mmol/L |
2. Sample Size Used for the Test Set and Data Provenance
The document explicitly states that the correlation study was performed with "clinical patient serum samples". However, it does not specify the exact sample size used for this comparison. The provenance of the data is not explicitly mentioned but is implied to be clinical samples relevant to sodium measurement. The study design is retrospective in the sense that it evaluates the performance of the new assay against an existing method on collected samples, but it doesn't specify if these were newly collected prospective samples or existing archived samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of information is not applicable to this submission. The "ground truth" for sodium concentration measurements in this context is the result obtained by a legally marketed and accepted method (Ion-Selective Electrode, ISE), not a subjective assessment by human experts.
4. Adjudication Method for the Test Set
Not applicable. There was no human adjudication process involved as the "ground truth" was established by a reference analytical method (ISE).
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
Not applicable. This submission is for an in-vitro diagnostic (IVD) assay that directly measures a biomarker (sodium concentration). It is not an AI-assisted diagnostic imaging or classification tool that would involve human readers or an MRMC study.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
The device itself is a "standalone" enzymatic assay in the sense that its results are generated by the chemical reaction and photometric measurement, not requiring direct human interpretation in the same way an imaging algorithm might. The performance described (precision, correlation, etc.) represents the intrinsic performance of the assay system.
7. The Type of Ground Truth Used
The ground truth used for comparison and validation was the results obtained from a legally marketed predicate device using the Ion-Selective Electrode (ISE) method. This represents a well-established and accepted analytical method for measuring sodium.
8. The Sample Size for the Training Set
Not applicable. This submission is for an enzymatic assay, not a machine learning or AI algorithm that requires a "training set" in the conventional sense. The assay's chemical and enzymatic principles are fixed, not learned from a large dataset.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no "training set" for this type of device. The assay development would have involved optimizing reaction conditions, reagent concentrations, and measurement parameters based on established biochemical principles and laboratory testing, not by training on a labeled dataset.
§ 862.1665 Sodium test system.
(a)
Identification. A sodium test system is a device intended to measure sodium in serum, plasma, and urine. Measurements obtained by this device are used in the diagnosis and treatment of aldosteronism (excessive secretion of the hormone aldosterone), diabetes insipidus (chronic excretion of large amounts of dilute urine, accompanied by extreme thirst), adrenal hypertension, Addison's disease (caused by destruction of the adrenal glands), dehydration, inappropriate antidiuretic hormone secretion, or other diseases involving electrolyte imbalance.(b)
Classification. Class II.