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The AxSYM Cyclosporine assay is a Fluorescence Polarization Immunoassay (FPIA) in vitro reagent system for the quantitative measurement of cyclosporine (cyclosporine A) in human whole blood as an aid in the management of cardiac, liver, and renal transplant patients.

The AxSYM Cyclosporine assay requires the use of the AxSYM System, a random and continuous access immunoassay analyzer performs all sample and reagent transfers, incubations, and data processing, and completes the assay with a printed report. Samples (calibrators, controls, and specimens) are pretreated to minimize interference from endogenous protein-bound fluorescent compounds. Sample pretreatment consists of lysing the erythrocytes in the whole blood with Solubilization Reagent and precipitating protein with Precipitation Reagent. Cyclopsorine is dissolved into the liquid phase. The mixture is centrifuged to generate a clarified extract. The AxSYM Cyclopsorine assay is performed on the clarified extract. The AxSYM Cyclosporine Reagents and pretreated sample are pipetted in the following sequence:

• Pretreated sample, Cyclosporine Antibody, Cyclosporine Pretreatment and Solution 4 (Line Diluent) required for one test are pipetted by the Sample Probe into one well of a Reaction Vesssel (RV) to form a Sample Solution,
• Cyclosporine Fluorescein Tracer is added to a second well of the RV.
• The RV is immediately transferred into the Processing Center. Further pipetting is done in the Processing Center by the Processing Probe.
• Aliquots of Solution 4 and Sample Solution are dispensed into the RV curvette.
• The polarized fluorescent background is measured by the FPIA optical assembly.
• Second aliquots of Solution 4 and Sample Solution, and an aliquot of . Cyclosporine Fluorescein Tracer are dispensed into the same RV curvette.
• The intensity of polarized fluorescent light is measured by the FPIA optical assembly.

The Abbott AxSYM® Cyclosporine assay is a new device, and its performance was evaluated by comparing it to a predicate device, the Abbott TDx®/TDxFLx® Cyclosporine Monoclonal Whole Blood assay.

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state pre-defined acceptance criteria (e.g., minimum correlation coefficient, slope range, intercept range). Instead, it presents the results of a comparison study and concludes that the device is "substantially equivalent" to the predicate. The performance is reported in terms of a linear regression analysis.

2. Sample Size and Data Provenance

• Test Set Sample Size: 754 specimens.
  • Heart transplant patients: 194
  • Kidney transplant patients: 330
  • Liver transplant patients: 230
• Data Provenance: Not explicitly stated regarding country of origin. The study appears to be retrospective, comparing the new device against the existing predicate device on collected samples.

3. Number of Experts and Qualifications for Ground Truth

This study compares a new quantitative assay (Abbott AxSYM Cyclosporine) against an existing, legally marketed quantitative assay (Abbott TDx/TDxFLx Cyclosporine Monoclonal Whole Blood). In such analytical performance studies for quantitative in vitro diagnostic devices, the "ground truth" is established by the reference method (the predicate device in this case) or a highly accurate laboratory method, rather than through expert human interpretation. Therefore, experts in the traditional sense (e.g., radiologists interpreting images) are not typically involved in establishing ground truth for this type of test.

4. Adjudication Method

Not applicable. As described above, this is an analytical comparison of two quantitative assays. Adjudication methods (like 2+1 or 3+1) are typically used when human interpretation of complex data (e.g., medical images) is involved to establish a consensus ground truth.

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

Not applicable. This is an analytical performance study of an in vitro diagnostic device, not a study involving human readers interpreting cases. Therefore, there is no discussion of how human readers improve with or without AI assistance.

6. Standalone Performance

Yes, a standalone performance study was done in the sense that the AxSYM Cyclosporine assay was run independently on the test samples, and its results were then compared to those generated by the predicate device. The performance metrics (correlation, slope, intercept) describe this standalone algorithm's (the AxSYM assay's) agreement with the predicate device.

7. Type of Ground Truth Used

The "ground truth" for comparison was the measurements obtained from the predicate device, the Abbott TDx®/TDxFLx® Cyclosporine Monoclonal Whole Blood assay. This is a common approach for demonstrating substantial equivalence for new in vitro diagnostic devices to existing, legally marketed ones.

8. Sample Size for the Training Set

The document does not provide details about a specific "training set" for the AxSYM Cyclosporine assay. Immunoassays like this are developed using established chemical and immunological principles, and calibration (using calibrators provided with the kit) is a standard part of their operation, not a "training set" in the machine learning sense. The linearity and operating range of the assay would typically be established during the development phase using various concentrations of cyclosporine.

9. How Ground Truth for the Training Set was Established

Not applicable in the machine learning context. For an immunoassay, the "ground truth" for calibrators (which function somewhat analogously to training data by defining the response curve) is established by precise preparations of known concentrations of the analyte (cyclosporine) using highly accurate methods, often traceable to international standards. The document mentions a calibrator range of 0 ng/mL to 800 ng/mL for the AxSYM Cyclosporine.

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