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The VerifyNow-P2Y12 Assay is a whole blood assay used in the laboratory or point of care setting to measure the level of platelet P2Y12 receptor blockade.

The VerifyNow System is a turbidimetric based optical detection system, which measures platelet induced aggregation as an increase in light transmittance. The system consists of a stand-alone instrument and disposable assay device with reagents based on microbead agglutination technology. The quality control system includes an electronic control, an assay device internal control, and two levels of liquid control. The instrument controls assay sequencing, establishes the assay temperature, controls the reagent-sample mixing for the required duration, determines the degree of platelet function, displays the results and status information to the user, and performs self-diagnostics.

The assay device contains a lyophilized preparation of human fibrinogen coated beads. adenosine-5-diphosphate (ADP), a peptide, a fatty acid, buffer, and preservative. The patient sample is citrated whole blood, which is automatically dispensed from the blood collection tube into the assay device by the instrument, with no blood handling required by the user.

Fibrinogen-coated microparticles are used in the VerifyNow-P2Y12 assay device to bind activated platelet GP IIb/Illa receptors. ADP is incorporated into the assay to activate platelets, and the reagent is formulated to specifically measure P2Y12 - mediated platelet aggregation.

When the activated platelets are exposed to the fibrinogen-coated microparticles, aggregation occurs in proportion to the number of activated platelet receptors. The VerifyNow-P2Y12 Assay reports results in P2Y12 Reaction Units (PRU).

Here's a breakdown of the acceptance criteria and study information for the Accumetrics VerifyNow P2Y12 Assay, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state pre-defined acceptance criteria for the VerifyNow P2Y12 Assay. Instead, it presents performance characteristics and demonstrates its ability to measure changes in P2Y12 receptor blockade in response to clopidogrel and its specificity compared to Light Transmittance Aggregometry (LTA).

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

• Sample Size for Main Performance Study: 147 subjects.
• Sample Size for Specificity Study: 10 individuals/blood donors.
• Data Provenance: The studies were performed in "clinical studies at 4 centers". The country of origin is not explicitly stated, but given the FDA 510(k) submission, it is highly likely to be within the United States. The studies appear to be prospective, as they involve "patients treated with clopidogrel" and include "before and after clopidogrel administration" measurements. The specificity study also involved drawing blood and adding inhibitors, indicating a prospective experimental design.

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

The submission does not rely on expert opinion to establish ground truth in the traditional sense for diagnostic image analysis or clinical endpoint assessment. Instead, the "ground truth" is established by:

• Pharmacological Intervention: The known effect of clopidogrel (a drug specifically designed to block the P2Y12 ADP receptor) is used as a reference for assessing the device's ability to measure P2Y12 receptor blockade.
• Predicate Device Comparison: The CHRONO-LOG Optical Aggregometer (Light Transmittance Aggregometry - LTA) with 5 uM ADP as the agonist serves as the comparative method. LTA is a well-established method for measuring platelet aggregation.
• Known Inhibitors: In the specificity study, a known specific P2Y12 inhibitor, 2-methylthio-AMP (2MeSAMP), was added to blood samples to establish the "ground truth" for maximal P2Y12 inhibition.

Therefore, no external "experts" were explicitly used to interpret data for ground truth establishment; rather, established biochemical and pharmacological principles and comparative methods were employed.

4. Adjudication Method for the Test Set

Not applicable. As described above, the ground truth is established through pharmacological means and comparison to a predicate device, not through expert consensus on interpretations that would require adjudication.

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

No. This is an in-vitro diagnostic (IVD) device for measuring a biological marker (platelet P2Y12 receptor blockade). MRMC studies are typically applicable to medical imaging devices where human readers interpret images, and the AI's role is to assist or replace that interpretation. This submission describes standalone device performance.

6. Standalone (i.e., algorithm only without human-in-the-loop performance) Study

Yes, the studies described are standalone performance evaluations of the VerifyNow P2Y12 Assay. The device measures in vitro platelet function automatically and provides a quantitative result (PRU). There is no human interpretation of an algorithm's output or human-in-the-loop component described in the performance evaluation.

7. Type of Ground Truth Used

The ground truth used is a combination of:

• Pharmacological Effect: The known and expected biological response to a specific drug (clopidogrel) that targets the P2Y12 receptor.
• Comparative Reference Method: Light Transmittance Aggregometry (LTA) using 5 uM ADP as an agonist, which is a recognized method for assessing platelet aggregation.
• Known Biochemical Inhibition: The use of a specific chemical inhibitor (2MeSAMP) to induce a known level of P2Y12 inhibition.

8. Sample Size for the Training Set

The document does not explicitly mention a separate "training set" or "validation set" in the context of machine learning model development. This is a traditional IVD device, not an AI/ML-driven device that typically requires distinct training and test sets for model development and evaluation. The described studies are performance evaluations of a pre-defined assay.

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

Not applicable, as a distinct training set for an AI/ML model is not described or implied in this 510(k) summary. The device's underlying principles (turbidimetric optical detection, fibrinogen-coated beads, ADP, specific additives) are based on established biochemical and biophysical mechanisms, not data-driven machine learning.

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