(60 days)
The Ammonia assay is used for the quantitation of ammonia in human plasma. Ammonia measurements are used in the diagnosis and treatment of severe liver disorders, such as cirrhosis, hepatitis, and Reye's syndrome.
Ammonia is an in vitro diagnostic assay for the quantitative determination of ammonia in human plasma. The Ammonia assay is a clinical chemistry assay which utilizes the amination of x-ketoglutarate by ammonia (NH3) along with the concomitant oxidation of NH2DPH. These reactions, catalyzed by glutamate dehydrogenase (GLDH), produce glutamate and NHzDP*. The oxidation of NHzDPH produces a decrease in absorbance at 340 nm which is directly proportional to the concentration of ammonia in the sample.
- Table of Acceptance Criteria and Reported Device Performance:
| Performance Characteristic | Acceptance Criteria (implied by predicate) | Reported Device Performance (Ammonia assay) |
|---|---|---|
| Correlation with Predicate | "Similar Performance Characteristics" to Roche Cobas Mira Plus | Correlation coefficient = 0.9969 |
| Slope (Method Comparison) | Close to 1.0 | 1.044 |
| Y-intercept (Method Comparison) | Close to 0 (or within acceptable clinical limits) | 12.020 umol/L |
| Precision (Total %CV - Level 1) | Acceptable for clinical use (implied by predicate) | 13.8% |
| Precision (Total %CV - Level 2) | Acceptable for clinical use (implied by predicate) | 5.2% |
| Precision (Total %CV - Level 3) | Acceptable for clinical use (implied by predicate) | 3.0% |
| Linearity | Up to the predicate's range (implied by predicate) | Up to 630 µmol/L |
| Limit of Quantitation (Sensitivity) | Comparable to predicate (implied by predicate) | 19 µmol/L |
| Assay Range | Similar to predicate | "minor difference" from predicate |
Note: The acceptance criteria are largely implied by the claim of substantial equivalence to the Roche Cobas Mira Plus Automated Chemistry System Ammonia assay (K914750). The FDA's clearance of K914750 would have established acceptable performance limits. The Ammonia assay demonstrates comparable and statistically similar performance to that predicate.
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Sample Size Used for the Test Set and Data Provenance:
- Sample Size: The document does not explicitly state the sample size used for the comparative performance studies (method comparison and precision studies). It mentions "three levels of control material" for precision studies. For the method comparison, it refers to "comparative performance studies" which likely involved patient samples, but the number is not specified.
- Data Provenance: Not explicitly stated, but clinical chemistry assays typically use human plasma. The document does not specify the country of origin, or if the study was retrospective or prospective.
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Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts:
- This information is not applicable to this submission. The Ammonia assay is an in vitro diagnostic (IVD) clinical chemistry assay where the "ground truth" is established by a reference method (the predicate device) or by measuring known concentrations in control materials. It does not involve human interpretation of images or other subjective data that would require expert consensus.
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Adjudication Method for the Test Set:
- This information is not applicable. As an IVD clinical chemistry assay, there is no need for an adjudication method for a test set in the way it's used for image-based diagnostics. The performance is assessed by direct comparison of numerical results.
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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:
- This information is not applicable. This is an in vitro diagnostic assay and does not involve human readers interpreting images or data, nor does it incorporate AI.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- This is a standalone device in the sense that the assay measures ammonia in a sample without direct human intervention in the result generation once the sample is loaded and the assay begins on the ALCYON™ Analyzer. The performance characteristics described (correlation, precision, linearity, sensitivity) are all "algorithm only" or "device only" performance.
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The Type of Ground Truth Used:
- The primary "ground truth" for the comparative performance studies was the Roche Cobas Mira Plus Automated Chemistry System Ammonia assay (K914750), which served as the legally marketed predicate device. For precision, the ground truth was implied by the known concentrations in the three levels of control material.
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The Sample Size for the Training Set:
- This information is not applicable for this type of device. The Ammonia assay is a chemical reaction-based in vitro diagnostic assay, not a machine learning or AI algorithm that requires a "training set" in the conventional sense. The assay's parameters are derived from scientific principles and optimized through experimental design, not statistical training on a large dataset.
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How the Ground Truth for the Training Set was Established:
- This information is not applicable for the reasons stated above (point 8). There is no "training set" for this chemical assay.
§ 862.1065 Ammonia test system.
(a)
Identification. An ammonia test system is a device intended to measure ammonia levels in blood, serum, and plasma, Ammonia measurements are used in the diagnosis and treatment of severe liver disorders, such as cirrhosis, hepatitis, and Reye's syndrome.(b)
Classification. Class I.