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Reagents: ST AIA-PACK Homocysteine is designed for IN VITRO DIAGNOSTIC USE ONLY for the quantitative measurement of homocysteine in human serum, heparinized plasma or EDTA plasma using a Tosoh AlA System Analyzer. Homocysteine measurements are used in the diagnosis and treatment of hyperhomocysteinemia or homocystinuria. Calibrators: ST AIA-PACK Homocysteine Calibrator Set is intended for IN VITRO DIAGNOSTIC USE ONLY for the callbration of the ST AIA PACK Homocysteine assay using a Tosoh AIA System Analyzer. Controls: The AIA-PACK Homocysteine Control Set is intended for IN VITRO DIAGNOSTIC USE ONLY for performing quality control procedures with the ST AIA-PACK Homocysteine Assay.

Device Description

The ST AIA-PACK Homocysteine is a competitive enzyme immunoassay which, after sample pretreatment, is performed entirely in the ST AIA-PACK Homocysteine test cups. Oxidized homocysteine is reduced by tris (2-carboxyethyl) phosphine (TCEP) to the free form and converted to S-adenosyl-L-homocysteine (SAH) by the SAH hydrolase and excess adenosine prior to the immunoassay. SAH present in the pretreated sample competes with immobilized SAH on magnetic beads for binding sites of the enzyme-labeled anti-SAH mouse monoclonal antibody. The magnetic beads are washed to remove unbound anti-SAH mouse monoclonal antibody and are then incubated with a fluorogenic substrate, 4-methylumbelliferyl phosphate (4MUP). The rate of fluorescence produced by the enzyme reaction indicates the amount of enzyme-labeled anti-SAH mouse monoclonal antibody. The amount of antibody that binds to the beads is inversely proportional to the homocysteine concentration in the test sample. A standard curve is constructed, and unknown sample concentrations are calculated using this curve.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the ST AIA-PACK Homocysteine device, based on the provided text:

Acceptance Criteria and Device Performance

Acceptance Criteria Category	Specific Criteria/Study Goal	Reported Device Performance
Precision	Within-run (Intra-assay): To demonstrate consistency of results within a single run.	Coefficient of Variation (CV) ranged from 3.1% to 4.3% across various sample types (EDTA Plasma, HEP Plasma, Serum) and homocysteine concentrations.
	Total Precision (Inter-assay): To demonstrate consistency of results across multiple runs and days.	Coefficient of Variation (CV) ranged from 3.6% to 5.0% across various sample types (EDTA Plasma, HEP Plasma, Serum) and homocysteine concentrations.
Linearity/Reportable Range	To demonstrate that the assay accurately measures homocysteine concentrations across a specified range.	Demonstrated to be linear from 0.5 to 50.0 µmol/L.
Detection Limit	To determine the lowest concentration of homocysteine that can be reliably detected.	Limit of Detection (LoD) estimated at 0.334 µmol/L.
Interference	To ensure that common endogenous and exogenous substances do not significantly affect assay results (recovery within 100 +/- 10%).	No interference observed from: Hemoglobin (up to 1445 mg/dL), free bilirubin (up to 18 mg/dL), conjugated bilirubin (up to 18 mg/dL), Lipemia (up to 1667 mg/dL triglyceride), Added protein (up to 50 mg/ml human g-globulin), Ascorbic acid (up to 20 mg/dL), EDTA-2K (up to 5.0 mg/mL), Heparin (up to 100 U/mL).
Specificity (Cross-reactivity)	To determine the extent to which other compounds similar to homocysteine are incorrectly identified as homocysteine.	Cross-reactivity: < 1% for Adenosine, L-Cystathionine, L-Cysteine, L-Glutathione, L-Methionine. < 7% (6.99%) for DL-Homocysteine thiolactone. S-Adenosyl-L-methionine showed 1.26% cross-reactivity.
Method Comparison	To demonstrate agreement between the new device and an existing legally marketed device (predicate device).	Correlation Coefficient (R): 0.984 against an alternate method for 138 EDTA plasma specimens. Deming regression: Slope = 1.079, Intercept = 0.193. Regular regression: Slope = 1.061, Intercept = 0.499.
Matrix Comparison	To demonstrate comparable results across different specimen types (EDTA plasma vs. heparinized plasma, EDTA plasma vs. serum).	EDTA plasma vs. Heparinized plasma (N=98): Corr Coef (R) = 0.991; Deming Slope = 1.007, Intercept = -0.235. EDTA plasma vs. Serum (N=98): Corr Coef (R) = 0.991; Deming Slope = 1.007, Intercept = -0.235.
Reference Range	To establish the expected range of homocysteine values in a healthy population.	Established reference interval: 6.6 - 17.8 µmol/L (central 95% of 130 apparently healthy individuals).
Stability	To determine the shelf life and in-use stability of the reagents and components.	Shelf life: 12 months (all components at 2-8°C). In-use stability: Test cups (40 hrs at 18-25°C, 30 days at 2-8°C), Calibrator Set (1 day at 2-8°C), Sample Diluting Solution (9 days semi-automated at 18-25°C, 90 days manual at 2-8°C), Pretreatment Reagent (20 hrs at 18-25°C, 1 day manual at 2-8°C), Control Set (14 days at 2-8°C, 1 day at 18-25°C).

Study Details:

Sample Size Used for the Test Set and the Data Provenance:
- Precision (Within-run & Total): 9 pooled samples (3 each of EDTA plasma, heparinized plasma, and serum). Undisclosed country of origin, prospective (presumably created and tested for the study).
- Linearity: Not specified as a separate test set, but determined as part of the method validation.
- Limit of Detection: 60 replicates of a blank sample and 10 replicates each of 6 low-level samples. Undisclosed country of origin, prospective.
- Interference: Human specimens (number not specified) for EDTA plasma, heparinized plasma, and serum. Undisclosed country of origin, prospective.
- Specificity (Cross-reactivity): Unspecified number of formulations with various compounds. Undisclosed country of origin, prospective.
- Method Comparison: 138 unaltered EDTA plasma specimens. Undisclosed country of origin. The term "patient samples" suggests retrospective clinical samples.
- Matrix Comparison: 98 unaltered specimens for EDTA plasma vs. heparinized plasma; 98 unaltered specimens for EDTA plasma vs. serum. Undisclosed country of origin. The term "unaltered specimens" suggests retrospective clinical samples.
- Reference Range: 130 apparently healthy individuals. Undisclosed country of origin, prospective.
Number of Experts Used to Establish the Ground Truth for the Test Set and the Qualifications of Those Experts:
- This is an in vitro diagnostic (IVD) device, specifically an immunoassay for measuring homocysteine levels in biological samples. The "ground truth" for such devices is typically established through a combination of:
  - Reference Methods/Materials: For quantitative measurements, there isn't a "ground truth" derived from expert consensus in the same way as an imaging device. Instead, accuracy is assessed against highly characterized reference materials (like NIST SRM 1955 mentioned for traceability) or established reference methods.
  - Predicate Device Comparison: The study also compares the device's results to a legally marketed predicate device (Siemens IMMULITE 2000 Homocysteine Immunoassay), which serves as a clinical benchmark.
- Therefore, the concept of "experts" establishing a diagnostic ground truth for individual cases, as would be common in imaging or pathology studies, does not directly apply in this context. The methodologies (CLSI protocols) define the acceptance criteria for analytical performance.
Adjudication Method for the Test Set:
- Not Applicable. As mentioned above, this is an IVD device measuring a biomarker. The performance is assessed against analytical standards (precision, linearity, detection limit) and agreement with reference methods/predicate devices, not through a diagnostic adjudication process by experts.
If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- Not Applicable. This is an automated in vitro diagnostic test. It does not involve human readers or AI assistance in interpreting diagnostic images or clinical cases.
If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done:
- Yes, this is an entirely standalone algorithm/device performance. The ST AIA-PACK Homocysteine assay is a competitive enzyme immunoassay performed on a TOSOH AIA System Analyzer. The result is a quantitative measurement of homocysteine, directly reported by the instrument based on its internal algorithms and calibration. There is no human intervention in the result generation or interpretation beyond operating the analyzer and reviewing the numerical output.
The Type of Ground Truth Used:
- Analytical Ground Truth / Reference Standards / Clinical Correlation.
  - For traceability, the calibrators are referred to NIST Standard Reference Material 1955, which represents a highly characterized and accurate reference for homocysteine.
  - For method comparison, the "ground truth" is effectively the results obtained from the predicate device (alternate method), as per clinical practice.
  - For other analytical performance characteristics (precision, linearity, LoD, interference), the "ground truth" is based on the expected behavior of known concentrations of analytes and interferents, often prepared in a laboratory setting or derived from well-characterized clinical samples according to CLSI guidelines.
  - For the reference range, the "ground truth" is the statistical distribution of homocysteine levels in a healthy population, determined by measuring 130 apparently healthy individuals.
The Sample Size for the Training Set:
- Not applicable / Not explicitly stated for a typical "training set." As an immunoassay, this device's "training" involves the development and optimization of reagents, antibodies, and the assay protocol itself, along with the establishment of calibration curves. These are informed by biochemical principles and extensive in-house R&D, rather than a discrete "training set" of labeled data in the context of machine learning or AI. The provided text describes analytical performance verification and validation.
How the Ground Truth for the Training Set Was Established:
- Not applicable in the context of explicit machine learning training sets. The "ground truth" for the development of the assay (analogous to training) would derive from fundamental chemistry and immunology principles, combined with the use of purified homocysteine standards and knowledge of biological matrices. The process involves iterative optimization and validation against known concentrations and established analytical performance metrics, guided by international standards like CLSI.

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