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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.

The cobas 6000 analyzer series with an ISE module is an Ion-Selective Electrode (ISE) system for the determination of sodium, potassium, and chloride in serum, plasma, and urine. The cobas 6000 analyzer series, including the cobas c 501 with ISE for Serum, Plasma and Urine sample types was previously cleared in K060373. This premarket notification seeks to obtain FDA review and clearance for the cobas c 501 ISE, Modified Calibration for Serum, Plasma and Urine sample types.

An 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 in solution (see package insert for further explanation).

Aqueous ISE Standards Low and High were cleared in K053165. The modified calibration in this submission included the use of ISE Standards Low (S1) and High (S2) for 2-point calibration and the Standard High for compensation (S3). Previously, a serum-based ISE compensator was used for S3 compensation. The modification is switching from serum-based ISE compensator for S3 to ISE Standard High. In the new calibration scheme, the ISE Standard High will be used for both S2 and S3.

The provided text describes a 510(k) summary for the cobas c 501 ISE, Modified Calibration for Sodium, Potassium, and Chloride assays. It focuses on demonstrating substantial equivalence to a predicate device rather than presenting a study for meeting acceptance criteria in the typical AI/ML context. However, I can extract and structure the information into the requested format by interpreting "acceptance criteria" as the performance parameters considered for substantial equivalence and "reported device performance" as the data provided for the modified device.

Here's the breakdown:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly derived from the performance of the predicate device and the new device showing comparable or improved performance for various metrics. The study aims to demonstrate that the modified calibration maintains or improves performance.

2. Sample Size Used for the Test Set and Data Provenance

The "test set" here refers to the samples used for method comparison studies.

• Sodium (Serum/Plasma): N = 52 (Plasma, Modified), N = 51 (Serum, Modified). N = 51 (Plasma, Predicate).
• Sodium (Urine): N = 100 (Modified). N = 51 (Predicate).
• Potassium (Serum/Plasma): N = 52 (Plasma, Modified), N = 54 (Serum, Modified). N = 51 (Plasma, Predicate).
• Potassium (Urine): N = 105 (Modified). N = 51 (Predicate).
• Chloride (Serum/Plasma): N = 52 (Plasma, Modified), N = 53 (Serum, Modified). N = 51 (Plasma, Predicate).
• Chloride (Urine): N = 105 (Modified). N = 51 (Predicate).

Data Provenance: The document does not specify the country of origin of the data. The studies appear to be prospective, laboratory-based analytical studies designed to test the performance of the modified device against a reference method and the predicate device. They are not clinical studies necessarily involving patient outcomes.

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. This is a submission for an in vitro diagnostic (IVD) device (a measurement instrument and reagents) used to quantify specific analytes (sodium, potassium, chloride) in biological samples. The "ground truth" for the test set is established by recognized reference methods (e.g., Flame Photometry, Coulometry) which are laboratory instruments, not human experts making diagnostic decisions. There were no experts involved in establishing ground truth for these analytical performance studies.

4. Adjudication Method for the Test Set

This is not applicable. As stated above, this is an analytical performance study using objective reference standard measurements, not human interpretation requiring adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

This is not applicable. MRMC studies are typically performed for AI/ML diagnostic interpretation algorithms where human readers' performance is evaluated and compared with and without AI assistance. This submission is for an IVD device where measurements are performed by an automated analyzer, not human "readers" interpreting cases.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done

The study described is inherently a "standalone" or "algorithm only" performance evaluation relative to the context of AI/ML. The device (cobas c 501 ISE with modified calibration) performs the measurement and produces results without human interpretation of raw data in the same way an AI algorithm would. The study directly evaluates the analytical performance of this automated system.

7. The Type of Ground Truth Used

The ground truth for the analytical performance studies was established using:

• Reference Methods:
  • Flame Photometry for Sodium (Plasma, Urine) and Potassium (Plasma, Urine).
  • Coulometry for Chloride (Plasma, Urine).
• Predicate Device Performance: The original cobas c 501 ISE Gen. 2 with serum-based ISE Compensator (K053165) served as a benchmark for comparison to demonstrate substantial equivalence, rather than a "ground truth" per se.

8. The Sample Size for the Training Set

This is not applicable in the context of AI/ML. This device is a chemistry analyzer with a modified calibration process, not a machine learning algorithm that requires a "training set" in the conventional sense. The "training" of the device involves the 2-point calibration and compensation using ISE Standards Low (S1) and High (S2, S3), as described in the submission.

9. How the Ground Truth for the Training Set was Established

This is not applicable in the context of AI/ML. The "ground truth" for the calibration process is established by the known concentrations of the ISE Standards Low (S1) and High (S2, S3). These are manufactured with highly controlled, known concentrations, serving as the basis for the instrument's calibration.

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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.

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.

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