(30 days)
The ISE module of the Roche / Hitachi systems is intended for the quantitative determination of sodium, potassium, and chloride in serum, plasma, or urine using ion-selective electrodes.
Sodium measurements 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.
Potassium measurements are used to monitor electrolyte balance in the diagnosis and treatment of disease conditions characterized by low or high blood potassium levels. Chloride measurements are used in the diagnosis and treatment of electrolyte and metabolic disorders such as cystic fibrosis and diabetic acidosis.
An Ion-Selective Electrode (ISE) makes use of the unique properties of certain membrane materials to develop an electrical potential (electromotive force, EMF) for the measurements of ions in solution. The electrode has a selective membrane in contact with both the test solution and an internal filling solution. The internal filling solution contains the test ion at a fixed concentration. Because of the particular nature of the membrane, the test ions will closely associate with the membrane on each side. The membrane EMF is determined by the difference in concentration of the test ion in the test solution and the internal filling solution. The EMF develops according to the Nernst equation for a specific ion is solution (see package insert for further explanation).
The complete measurement system for a particular ion includes the ISE, a reference electrode and electronic circuits to measure and process the EMF to give the test ion concentration. The sodium and potassium electrodes are based on neutral carriers and the chloride electrode is based on an ion exchanger.
This document describes the acceptance criteria and the study performed for the ISE Indirect Na, K, Cl for Gen.2 device.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied by the "Labeled performance characteristics" for the modified device, and the reported performance is directly listed.
| Feature | Analyte | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|---|
| Precision (CV) | Sodium (Plasma) | Low CV (e.g., 0.98) with predicate device | y= 1.000x - 1.300, r = 0.988 (n=58) |
| Potassium (Plasma) | High correlation (e.g., >0.99) with predicate device | y= 1.000x - 0.070, r = 0.999 (n=58) | |
| Chloride (Plasma) | High correlation (e.g., >0.99) with predicate device | y= 0.993x - 0.664, r = 0.994 (n=58) | |
| Endogenous Interferences | Hemolysis | No significant interference up to 1000 mg/dL hemoglobin (Na, Cl) | Confirmed for Sodium and Chloride. Potassium showed interference >100 mg/dL. |
| Icterus | No significant interference up to 60 mg/dL bilirubin | Confirmed for conjugated and unconjugated bilirubin. | |
| Lipemia | No significant interference up to 2000 mg/dL | Confirmed. |
2. Sample Size Used for the Test Set and Data Provenance
- Precision (Test Set):
- Plasma (Na, K, Cl): n=21 for between-day imprecision.
- Urine (Na, K, Cl): n=21 for between-day imprecision.
- Method Comparison (Test Set):
- Plasma (Na, K, Cl): n=58 for comparison against the predicate device (Hitachi 911 reagents).
- Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. It is implied to be prospective testing conducted by Roche Diagnostics.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
Not applicable. This device is an in vitro diagnostic (IVD) for quantitative measurements of analytes (Na, K, Cl). Ground truth is established by reference methods or predicate devices, not by expert interpretation of images or clinical assessments.
4. Adjudication Method for the Test Set
Not applicable. Ground truth for quantitative IVD devices typically involves comparisons to established reference methods or predicate devices, not adjudicated expert consensus.
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 device is an in vitro diagnostic (IVD) for quantitative measurements. It is not an AI-assisted diagnostic tool that involves human readers.
6. If a Standalone (i.e. algorithm only without human-in-the loop performance) was done
This is a standalone in vitro diagnostic device. Its performance is evaluated based on its ability to accurately measure electrolyte concentrations without direct human interpretation beyond specimen handling and instrument operation. The studies described (precision, linearity, method comparison) reflect its standalone performance.
7. The Type of Ground Truth Used
- Precision and Linearity: The term "ground truth" for these studies refers to the expected or actual concentration values of the analytes in the control or linearity samples used. These are typically prepared using either gravimetric/volumetric methods with high-purity standards or by using certified reference materials.
- Method Comparison: The predicate device (original ISE Na, K, Cl, K953239, specifically the Hitachi 911 reagent) serving on the "x method" acts as the reference or "ground truth" for evaluating the modified device's agreement. The document also mentions "Flame Photometry, Coulometry with NIST reference material" as traceability for the modified device, implying these highly accurate methods serve as the ultimate ground truth for the measurements.
8. The Sample Size for the Training Set
Not applicable. This device is an Ion-Selective Electrode (ISE) based system, not an AI/ML algorithm that requires a "training set" in the conventional sense. Its performance is based on electrochemical principles and calibration using known standards.
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 device is calibrated using ISE Standard Low (S1) and ISE Standard High (S2) and an ISE Compensator (S3), for which the "ground truth" concentrations are established through methods traceable to NIST reference materials, flame photometry, and coulometry.
§ 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.