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The AFP method is an in vitro diagnostic test for the quantitative measurement of alpha-fetoprotein in human serum on the Dimension Vista® system. Measurements of alpha-fetoprotein are used as an aid in managing non-seminomatous testicular cancer when used in conjunction with physical examination, histology/pathology, and other clinical evaluation procedures.

For the calibration of the Alpha-Fetoprotein (AFP) method on the Dimension Vista® System.

Method: The AFP method is a homogeneous, sandwich chemiluminescent immunoassay based on LOCI™ technology. The LOCT™ reagents include two synthetic bead reagents and a biotinylated anti-AFP monoclonal antibody fragment. The first bead reagent (Chemibeads) is coated with an anti-AFP monoclonal antibody and contains chemiluminescent dye. The second bead reagent (Sensibeads) is coated with streptavidin and contains a photosensitizer dve. Sample is incubated with biotinylated antibody and Chemibeads to form bead-AFP-biotinylated antibody sandwiches. Sensibeads are added and bind to the biotin to form bead-pair immunocomplexes. Illumination of the complex at 680 nm generates singlet oxygen from Sensibeads which diffuses into the Chemibeads, triggering a chemiluminescent reaction. The resulting signal is measured at 612 nm and is a direct function of the AFP concentration in the sample.

Calibrator: The LOCI 5 Calibrator is a liquid multi-analyte product containing AFP from human cord serum. An additional analyte (CEA from human tissue culture) is contained in the product and will be included in the submission to FDA with its respective method. The kit consists of ten vials, two each of five levels containing 2 mL per vial. Description of the manufacturing, value assignment and stability testing processes are provided.

For the Siemens Healthcare Diagnostics Inc. Dimension Vista® AFP reagent cartridge and LOCI 5 calibrator (K071597):

1. Table of Acceptance Criteria and Reported Device Performance

   The document does not explicitly state acceptance criteria in a quantitative format (e.g., a specific threshold for correlation coefficient or slope). Instead, it presents performance data and concludes "good analytical and clinical agreement." The substantial equivalence claim is based on this agreement with the predicate device.

   Performance Metric (Device: Dade Behring Dimension Vista® AFP Method)	Reported Device Performance (vs. Predicate Abbott AxSYM® AFP Method)
   Slope (Passing-Bablok linear regression)	0.93
   Intercept (ng/mL)	0.1
   Correlation Coefficient	0.995

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

   • Sample Size for Test Set: 317 patient samples.
   • Data Provenance: Not specifically mentioned, but the study is a "split sample method comparison," implying prospective collection of human serum samples for comparison against a predicate device. The country of origin is not specified.

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

   This study describes a method comparison for an in vitro diagnostic test measuring AFP levels in serum. The "ground truth" in this context is the quantitative result provided by the predicate device (Abbott AxSYM® AFP method). This is not a study requiring expert readers to establish ground truth from images or clinical assessments.

4. Adjudication Method for the Test Set

   Not applicable. This is a quantitative method comparison study against a predicate device, not a study involving expert adjudication of interpretations.

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

   No. This document describes a method comparison study for an in vitro diagnostic device, not a comparative effectiveness study involving human readers and AI assistance for interpretation.

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

   Yes, in essence. The study evaluates the performance of the Dimension Vista® AFP method (the "algorithm/device") by directly comparing its quantitative results to those of a predicate device using patient samples. This is a standalone performance evaluation of the assay itself.

7. Type of Ground Truth Used

   The "ground truth" for this method comparison study is the quantitative Alpha-Fetoprotein (AFP) concentration obtained from the predicate device (Abbott AxSYM® AFP method) for each human serum sample.

8. Sample Size for the Training Set

   The document does not provide information about a separate "training set" for the Dimension Vista® AFP method itself. This is a performance validation of a finished assay and calibrator. The development and internal validation of the assay (e.g., defining reagent concentrations, detection parameters) likely involved numerous experiments and historical data, but these are not disclosed as a distinct "training set" in a machine learning sense. Clinical validation studies for IVDs typically focus on demonstrating performance against established methods or clinical outcomes.

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

   As noted in point 8, a "training set" in the context of a machine learning algorithm is not explicitly described. For the development of the assay, the "ground truth" for calibrating and establishing the assay's performance characteristics would involve using certified reference materials (e.g., traceable to WHO Reference preparation for human AFP (72/225)) and well-characterized human samples. The document states that the device is "Traceable to the World Health Organization (WHO) Reference preparation for human AFP (72/225)," indicating the standard used for establishing accuracy and calibration.

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