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The i-STAT cTnl test is an in vitro diagnostic test for the quantitative measurement of cardiac troponin I in heparinized whole blood or plasma samples. Cardiac troponin I measurements can be used as an aid in the diagnosis and treatment of myocardial infarction and in the risk stratification of patients with acute coronary syndromes with respect to their relative risk of mortality.

The cartridge is to be used with the i-STAT 1 Analyzer, but not with the i-STAT Portable Clinical Analyzer or the Philips Medical Systems (formerly Agilent Technologies) Blood Analysis Module (BAM). As part of the i-STAT System, the cTnl test is to be used by trained health care professionals in accordance with a facility's policies and procedures.

The i-STAT cTnl test is contained in a single test cartridge. In use, the user scans a barcode and then places approximately 16 microliters of fresh whole blood in the cartridge is inserted into the thermally controlled i-STAT 1 Analyzer, and all analytical steps are performed automatically. Patient and user information may be entered into the analyzer via a keypad during the automated analysis cycle.

As the analyzer performs several quality checks and controls the temperature of the sensors via resistive heating to the underside of the sensor chips, the substrate/wash fluid is released into a conduit within the cartridge and a metered volume of the sample over the sensor chips. The enzyme-linked antibody conjugate dissolves into the sample and the sample incubates for a controlled time. The sample is then pushed into a waste chamber and the substrate/wash solution is brought over the sensors. The alkaline phosphatase captured on the cTnl sensor cleaves the substrate present in the substrate/wash fluid, giving rise to an amperometric signal which is measured.

The cTnl test cartridge is assembled from plastic components that provide the conduits for fluid handling and house the sensor chips. The test is identified to the user through the name and color code on the cartridge label and by the analyzer through features integral to the cartridge.

Here's a breakdown of the acceptance criteria and study information for the i-STAT cTnI Test, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state formal "acceptance criteria" in a numerical or pass/fail format for clinical performance as might be seen for a new device. Instead, it demonstrates "substantial equivalence" to a predicate device. The performance metrics presented are comparative.

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

• Test Set Sample Size:
  • i-STAT whole blood vs. Stratus CS plasma: 189 patient samples (all), 112 samples ([cTnI] < 3.0 ng/mL)
  • i-STAT plasma vs. i-STAT whole blood: 188 patient samples (all), 118 samples ([cTnI] < 3.0 ng/mL)
• Data Provenance: The studies were conducted at "three external clinical sites." The country of origin is not explicitly stated, but given the manufacturer's location (East Windsor, NJ) and the FDA submission, it is highly likely to be the United States. The data appears to be prospective or collected for the purpose of the study, as it involved "samples from patients who presented to the hospital with acute, severe, and prolonged chest pain" and analyses were performed by both the i-STAT system and the predicate.

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 and therefore not provided in this document. The "ground truth" for this device is established by quantitative measurement and comparison to a legally marketed predicate device (Dade Behring Stratus CS Cardiac Troponin I TestPak), which itself is established as a reliable diagnostic tool. The performance is assessed by comparing quantitative results, not by expert interpretation of images or clinical cases.

4. Adjudication Method for the Test Set

Not applicable. The study compares quantitative measurements of cardiac troponin I from two different laboratory methods, not subjective interpretations requiring adjudication.

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 is not an AI-based diagnostic device where human readers interact with AI. It's an in vitro diagnostic test for measuring a biomarker.

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

Yes, in a way that is relevant to IVD devices. The "standalone" performance for this device is represented by its analytical performance characteristics (like LLD, imprecision, insensitivity to hematocrit, isoform detection, drug interference) and its agreement with the predicate device when testing patient samples without human intervention in the result generation itself. The i-STAT 1 Analyzer performs all analytical steps automatically after sample insertion.

7. The Type of Ground Truth Used

The ground truth is established by the quantitative measurement of cardiac troponin I by a legally marketed predicate device (Dade Behring Stratus CS Cardiac Troponin I TestPak). The study seeks to show substantial equivalence of the i-STAT device's measurements to those of the predicate device. For analytical characteristics, the "ground truth" is based on controlled laboratory experiments (e.g., known hematocrit levels, spiked samples with isoforms or drugs) and established reference methods for LLD and imprecision calculations.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning or AI models. For an IVD device like this, method development and optimization would typically involve numerous internal R&D experiments rather than a distinct "training set" like in AI. Therefore, this information is not provided and not directly applicable in the AI sense.

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

As no specific "training set" for an AI model is described, this information is not provided and not applicable in the AI sense. The development of an IVD typically involves extensive analytical testing using reference materials, spiked samples, and clinical samples to optimize reagents, assay parameters, and ensure accurate and precise measurements.

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