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The ARK™ Lamotrigine Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of lamotrigine in human serum or plasma on automated clinical chemistry analyzers. Lamotrigine concentrations can be used as an aid in management of patients treated with lamotrigine.

The ARKTM Lamotrigine Calibrator is intended for use in calibration of the ARK Lamotrigine Assay.

The ARKTM Lamotrigine Control is intended for use in quality control of the ARK Lamotrigine Assay.

The ARK Lamotrigine Assay is a homogeneous immunoassay based on competition between drug in the specimen and lamotrigine labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly proportional to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenyzme NAD functions only with the bacterial enzyme used in the assay.

The ARK Lamotrigine Assay consists of reagents R1 anti-lamotrigine polyclonal antibody with substrate and R2 lamotrigine labeled with bacterial G6PDH enzyme. The ARK Lamotrigine Calibrator consists of a six-level set to calibrate the assay, and the ARK Lamotrigine Control consists of a three-level set used for quality control of the assay.

The ARK™ Lamotrigine Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of lamotrigine in human serum or plasma. The device performance was evaluated through various studies, including limit of quantitation (LOQ), assay range, recovery, linearity, method comparison, precision, interfering substances, specificity, and anticoagulant studies.

1. Acceptance Criteria and Reported Device Performance:

2. Sample Size and Data Provenance for Test Set:

• Recovery: Not explicitly stated, but "six replicates of each sample" were assayed across various concentrations, implying a total of 48 individual assays. Data provenance is human serum negative for lamotrigine, spiked with concentrated drug.
• Linearity: Not explicitly stated, but dilutions from a 48.00 µg/mL serum sample were made. Data provenance is human serum negative for lamotrigine, spiked with drug.
• Method Comparison (Study 1 - HPLC): 193 samples. Provenance not explicitly stated (e.g., country of origin, retrospective/prospective), but implied to be clinical samples or samples prepared to simulate clinical range.
• Method Comparison (Study 2 - Turbidimetric Immunoassay): 77 samples. Provenance not explicitly stated.
• Precision: Tri-level controls and three human serum pooled specimens. Each level assayed in quadruplicate twice a day for 20 days (160 measurements per control/pool level).
• Interfering Substances: Clinically high concentrations of substances in human serum with known lamotrigine levels (approximately 3 and 15 µg/mL).
• Specificity (Metabolites): Metabolites spiked into two separate samples each containing low (3 µg/mL) and high (15 µg/mL) therapeutic levels of lamotrigine.
• Specificity (Drug Interference): High concentration of each compound spiked into normal human serum with known lamotrigine levels (approximately 3 and 15 µg/mL).
• Anticoagulants: Not explicitly stated but implies a set of serum and plasma samples were tested.
• Sample Stability: Not explicitly stated, but samples were subject to various conditions (frozen, room temp, refrigerated, freeze/thaw cycles).

3. Number of Experts and their Qualifications for Ground Truth:
This type of device (quantitative immunoassay) relies on analytical performance against established reference methods or known concentrations, rather than expert interpretation of images or clinical data. Therefore, the concept of "experts establishing ground truth" as it applies to subjective assessments is not directly applicable here. The ground truth for analytical studies like recovery and linearity are based on gravimetric dilutions/known concentrations, and for method comparisons, the reference methods themselves (HPLC, predicate immunoassay) serve as the comparative standard.

4. Adjudication Method for the Test Set:
Not applicable for this type of analytical device validation. The studies involve quantitative measurements and comparisons to reference methods or known values, not subjective interpretations requiring adjudication.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
No, an MRMC comparative effectiveness study was not done. This type of study is typically performed for diagnostic devices requiring human interpretation of results, such as imaging studies, where the AI's effect on human reader performance is evaluated. This device is an automated immunoassay for quantitative measurement.

6. Standalone (Algorithm Only) Performance:
Yes, the entire submission describes the standalone performance of the ARK™ Lamotrigine Assay. The studies (LOQ, assay range, recovery, linearity, method comparison, precision, interference, specificity, stability) evaluate the device's analytical performance independently. The device operates on automated clinical chemistry analyzers without human intervention for result generation.

7. Type of Ground Truth Used:

• Known Concentrations/Gravimetric Dilutions: For studies such as Limit of Quantitation, Recovery, Linearity, Precision, Interfering Substances, Specificity (Metabolites, Drug Interference), and Anticoagulants, the ground truth is established by preparing samples with known, precise concentrations of lamotrigine or interfering substances through gravimetric dilutions.
• Reference Methods: For method comparison studies, the reference methods are High Performance Liquid Chromatography (HPLC) and a predicate turbidimetric immunoassay (QMS® Lamotrigine, K062966).

8. Sample Size for the Training Set:
Not applicable. This device is a quantitative immunoassay with "wet lab" validation, not an AI/ML algorithm that typically requires a large clinical "training set" to learn patterns. The validation process involves demonstrating analytical performance against known standards and comparative methods.

9. How Ground Truth for the Training Set Was Established:
Not applicable, as there isn't a "training set" in the context of an AI/ML algorithm. The device's analytical characteristics are determined through laboratory experiments using carefully prepared samples with known concentrations or by comparison to reference methods.

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The QMS® Lamotrigine assay is intended for the quantitative determination of lamotrigine in human serum or plasma on automated clinical chemistry analyzers.

Lamotrigine concentrations can be used as an aid in management of patients treated with lamotrigine.

The QMS® Lamotrigine Calibrator set is intended for use in calibration of the QMS Lamotrigine assay.

The QMS® Lamotrigine Control set is intended for use in quality control of the QMS Lamotrigine assay.

The QMS Lamotrigine assay system is a homogeneous assay utilizing particle agglutination technology and is based on the competitive binding principle.

The assay consists of reagents R1: anti-Lamotrigine sheep polyclonal antibody and R2: Lamotriginecoated microparticles. A six-level set of QMS Lamotrigine Calibrators (A through F) is used to calibrate the assay. A three-level set of QMS Lamotrigine Controls (1 thro the assay.

The provided document describes the K062966 QMS® Lamotrigine assay, a homogeneous particle-enhanced turbidimetric immunoassay for the quantitative determination of lamotrigine in human serum or plasma.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a table of "acceptance criteria" with specific pass/fail thresholds for each performance characteristic. Instead, it describes general methods used for testing and states that performance testing verified the device functions as intended and satisfied design specifications. However, we can infer some criteria and the reported performance from the "SUMMARY OF CLINICAL TESTING" section.

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

The document does not specify the exact sample sizes for the test sets used in each study (Accuracy and Linearity, Sensitivity, Method Comparison, Precision, Specificity, Interferences).

• Data Provenance: The document does not explicitly state the country of origin or if the data was retrospective or prospective. However, given it's a clinical chemistry assay for human serum/plasma, it's highly likely the samples were human biological specimens.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

This information is not provided in the document. For an in vitro diagnostic (IVD) assay like this, "ground truth" is typically established by reference methods or validated techniques, not necessarily by "experts" in the same way it would be for imaging diagnostics requiring interpretation.

4. Adjudication Method (e.g., 2+1, 3+1, none) for the Test Set

This information is not applicable and therefore not provided. Adjudication methods are typically relevant for studies involving human interpretation of results (e.g., in imaging or pathology where multiple readers might disagree). For a quantitative chemical assay, the "truth" is determined by the output of a reference instrument or method.

5. Multi Reader Multi Case (MRMC) Comparative Effectiveness Study

A Multi Reader Multi Case (MRMC) comparative effectiveness study was not performed or described. This type of study is relevant for evaluating the performance of human readers, often aided by AI, in complex diagnostic tasks (e.g., radiology). This device is a quantitative immunoassay, not an AI-assisted diagnostic imaging tool.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

This device is a standalone assay kit that performs a quantitative measurement on automated clinical chemistry analyzers. The "algorithm" is the biochemical reaction and measurement process itself, not a separate computational algorithm that assists a human. Therefore, the performance described is the standalone performance of the assay system without human interpretation as a primary component of the diagnostic result. The results (lamotrigine concentrations) are then used by clinicians for patient management.

7. Type of Ground Truth Used

The ground truth for this type of quantitative assay would typically be established by:

• Reference Methods: Highly accurate and precise analytical methods (e.g., Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Mass Spectrometry (LC-MS)) for determining the true concentration of lamotrigine in samples.
• Spiked Samples: Known concentrations of lamotrigine added to a matrix (e.g., human serum or plasma that is negative for lamotrigine) to assess accuracy and linearity.
• Patient Samples: Used for method comparison against a legally marketed predicate device or a well-established reference method.

The document implicitly refers to these by mentioning "Accuracy and linearity were determined..." and "Correlation studies were conducted using patient samples..." indicating that the "ground truth" for those studies would have been the results from a reference method or the assigned values from spiked samples.

8. Sample Size for the Training Set

The document does not mention a training set because this is a traditional immunoassay, not a machine learning or AI-based device that requires "training." The "training" of such a system involves developing the reagents and optimizing the assay conditions.

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

As there is no "training set" in the context of machine learning, this question is not applicable. The development of the assay's reagents and protocols is based on extensive biochemical research and optimization studies rather than "ground truth" established for a training dataset.

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