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The Chiron Diagnostics ACS:Centaur PSA2 Immunoassay is for the quantitative determination of prostate specific antigen in serum to aid in the management of cancer patients in whom changing concentrations of PSA are observed using the Chiron Diagnostics ACS:Centaur Automated Chemiluminescence Systems.

Prostate-specific antigen (PSA) is a single-chain glycoprotein normally found in the cytoplasm of the epithelial cells lining the acini and ducts of the prostate gland. PSA is a neutral serine protease of 240 amino acids involved in the lysis of seminal coagulum.

PSA is detected in the serum of males with normal, benign hypertrophic, and malignant prostate tissue. PSA is not detected in the serum of males without prostate tissue (because of radical prostatectomy or cystoprostatectomy) or in the serum of most females. The fact that PSA is unique to prostate tissue makes it a suitable marker for monitoring men with cancer of the prostate. PSA is also useful for determining possible recurrence after therapy when used in conjunction with other diagnostic indices.

The Chiron Diaqnostics ACS:Centaur PSA2 immunoassay is a two-site immunoassay using direct chemiluminometric technology, which uses constant amounts of two antibodies. The first antibody, in the Lite Reagent, is a purified polyclonal sheep anti-PSA antibody labeled with acridinium ester. The second antibody, in the Solid Phase, is a monoclonal mouse anti-PSA antibody covalently coupled to paramagnetic particles. A direct relationship exists between the amount of PSA present in the patient sample and the amount of relative light units (RLU's) detected by the system.

Acceptance Criteria and Device Performance for Chiron Diagnostics ACS:Centaur PSA2 Immunoassay (K981839)

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state numerical acceptance criteria in a dedicated section. The "Performance Data" section details the device's capabilities, and the high correlation with the predicate device (r = 0.99) strongly implies that this level of agreement was the acceptance criteria for accuracy to demonstrate substantial equivalence. The minimum detectable concentration demonstrates the lower limit of reliable measurement, implying an acceptance of this level of analytical sensitivity.

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

• Sample Size: 287 samples were used for the accuracy study comparing the ACS:Centaur PSA2 with the ACS:180 PSA2.
• Data Provenance: The document does not specify the country of origin of the data. It is a retrospective analysis comparing the performance of the new device against the predicate device using existing samples.

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

This device is an immunoassay for quantitative determination of PSA levels. The "ground truth" in this context is the quantitative measurement of PSA itself. Therefore, human experts are not directly involved in establishing the ground truth for individual samples in the same way they would be for image interpretation.

The ground truth for the comparison was established by the predicate device, the ACS:180 PSA2 Immunoassay. The performance of this predicate device would have been validated previously, likely involving method comparison studies with established reference methods or clinical samples.

4. Adjudication Method for the Test Set

The concept of an adjudication method (e.g., 2+1, 3+1) is not applicable here as the test set involves quantitative measurements from an immunoassay, not subjective interpretations requiring expert consensus. The comparison is a direct numerical correlation between the new device and the predicate device.

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

No MRMC comparative effectiveness study was conducted or is applicable for this type of device. This device is an automated immunoassay, meaning there are no human "readers" in the diagnostic process to compare or improve.

6. Standalone Performance Study

Yes, a standalone performance study was conducted. The "Performance Data" section describes the sensitivity and accuracy of the ACS:Centaur PSA2 Immunoassay as a standalone device, as it measures PSA concentration independently and then compares its output to the predicate device. The correlation study directly assesses the performance of the algorithm (the immunoassay technology) without human intervention in the measurement process.

7. Type of Ground Truth Used

The ground truth used for the comparison was measurements from a legally marketed predicate device (ACS:180 PSA2 Immunoassay). This is a form of comparative ground truth, where the performance of the new device is validated against an existing, accepted method. While not pathology or outcomes data directly, the predicate device's measurements are considered the established "truth" for this comparison of analytical performance. The clinical utility of PSA measurements (which pathology and outcomes data would inform) is assumed to be established by the predicate device's history and the broader medical literature.

8. Sample Size for the Training Set

The document does not specify a training set or its sample size. Immunoassays are generally developed and optimized through extensive experimentation and reagent optimization, rather than a "training set" in the machine learning sense. The performance data presented are for the validated, final device.

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

As no explicit training set is mentioned in the context of the immunoassay, the concept of establishing ground truth for it as per AI/ML terminology is not applicable. The development of the immunoassay involves chemical and biological engineering principles, with validation steps along the way, not a "ground truth" derived from expert consensus on a training dataset. The established "truth" for such systems typically comes from meticulously prepared reference materials, calibrators, and robust analytical methods.

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