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The B.R.A.H.M.S PCT sensitive KRYPTOR® is designed for automated detection of PCT (procalcitonin) in human serum or plasma (EDTA, heparin) samples by the immunofluorescent B·R·A·H·M·S PCT sensitive KRYPTOR® assay.

The B·R·A·H·M·S PCT sensitive KRYPTOR® is intended for use in conjunction with other laboratory findings and clinical assessments to aid in the risk assessment of critically ill patients on their first day of ICU admission for progression to severe sepsis and septic shock.

The B-R-A-H-M-S PCT sensitive KRYPTOR® assay is a homogeneous sandwich immunoassay for detection of PCT in human serum or plasma. The BrR.A.H.M.S KRYPTOR® analyzer is a fully automated system. The B·R·A·H·M·S KRYPTOR® analyzer is a closed system and can only operate utilizing special reagents provided by B.R.A.H.M.S Aktiengesellschaft. The measuring principle is based on Time-Resolved Amplified Cryptate Emission (TRACE®) technology, which measures the signal that is emitted from an immunocomplex with time delay.

The basis of the TRACE® technology is a non-radiative energy transfer from a donor [a cage-like structure with a europium ion in the center (cryptate)] to an acceptor (XL 665). The proximity of donor (cryptate) and acceptor (XL 665) in a formed immunocomplex and the spectral overlap between donor emission and acceptor absorption spectra on the one hand intensifies the fluorescent signal and on the other hand extends the life span of the acceptor signal, allowing for the measurement of temporally delayed fluorescence.

After the sample to be measured has been excited with a nitrogen laser at 337 nm, the donor (cryptate) emits a long-life fluorescent signal in the milli-second range at 620 nm, while the acceptor (XL 665) generates a short-life signal in the range of nanoseconds at 665 nm. When both components are bound in an immunocomplex, both the signal amplification and the prolonged life span of the acceptor signal occur at 665 nm, and the life is in the microsecond range. This delayed acceptor signal is proportional to the concentration of the analyte to be measured.

The specific fluorescence which is proportional to the antigen concentration is obtained through a double selection: spectral (separation depending on wave-length) and temporal (time resolved measurement). This enables an exclusive measurement of the signal emitted by the immunological complex and the ratio between the two wave-lengths (665/620) allows a real-time correction of the variations in optic transmission from the medium.

Here's a summary of the acceptance criteria and the study details for the B·R·A·H·M·S PCT sensitive KRYPTOR® Test System, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Sample Size (Method Comparison): 184 samples.
• Data Provenance: The samples were collected from three (3) sites. The country of origin is not specified, but the applicant is based in Germany with a US contact. The mention of "patients" and "clinical situations" suggests these were clinical samples. The study involved a comparison between a new device and a marketed predicate, indicating it was likely a retrospective analysis of previously collected samples or prospectively collected samples analyzed by both methods.

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

• Not Applicable / Not Provided: For this type of in vitro diagnostic device (immunoassay), the "ground truth" for the test set (method comparison) is the measurement result from the predicate device (B·R·A·H·M·S PCT LIA). Clinical "ground truth" for disease progression to severe sepsis/septic shock is based on consensus criteria (American College of Chest Physicians/Society of Critical Care Medicine), not individual expert adjudication of assay results. The device itself provides a quantitative measurement.

4. Adjudication Method for the Test Set

• Not Applicable: As this is an in vitro diagnostic device providing quantitative measurements, there is no direct expert adjudication method applied to the test results in the way it would be for image analysis or subjective clinical assessments. The comparison is between two quantitative assays.

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

• No: This is an in vitro diagnostic assay, not a medical imaging device or a diagnostic requiring human interpretation of complex data (beyond reading a number). Therefore, an MRMC study is not relevant or performed. The device provides a standalone quantitative result.

6. Standalone Performance Study (Algorithm only without human-in-the-loop performance)

• Yes, this is a standalone performance study. The B·R·A·H·M·S PCT sensitive KRYPTOR® is a fully automated system that measures PCT concentrations in human serum or plasma. Its performance for analytical sensitivity, functional assay sensitivity, precision, high dose hook effect, interference, and method comparison are all intrinsic to the device and assay reagents themselves, without human intervention in the measurement process. The "Interpretation of Results" section provides guidance on how clinicians should use the standalone PCT results in conjunction with other laboratory findings and clinical assessments.

7. Type of Ground Truth Used

• Method Comparison: The "ground truth" for the method comparison study was the measurements obtained from the legally marketed predicate device, the B·R·A·H·M·S PCT LIA assay. This is a comparative "truth" to an established method.
• Clinical Relevance: The interpretation of results (e.g., PCT > 2 ng/ml indicates high risk) implicitly relies on established clinical consensus criteria for severe sepsis and septic shock (American College of Chest Physicians/Society of Critical Care Medicine) as the clinical ground truth against which the PCT values are correlated to assess risk.

8. Sample Size for the Training Set

• Not explicitly provided/applicable in the same way: For in vitro diagnostic assays, especially those based on established immunofluorescence technology like TRACE®, the concept of a "training set" for an algorithm in the machine learning sense is not directly applicable. The assay formulation, antibody selection, and calibration are developed through R&D, not typically "trained" on a large dataset in the way an AI algorithm would be. The document describes the device's components and underlying technology rather than a data-driven training process.

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

• Not explicitly provided/applicable: As mentioned above, the assay's development isn't described in terms of a "training set" and "ground truth" in an AI/machine learning context. The "ground truth" in assay development is typically established through rigorous analytical verification and validation against known standards, spiked samples, and comparison with reference methods or clinically characterized samples during the research and development phases of the assay itself. The given document focuses on the validation of the finalized device.

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