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Immunoassay for the in vitro quantitative determination of total thyroxine in human serum and plasma.

The Elecsys® test principle is based on competition principle. Total duration of assay: 18 minutes (37°C).
• 1st incubation (9 minutes): Sample (15 µL) and a specific anti-T4 antibody labeled with a ruthenium complex (75 uL).
• 2nd incubation (9 minutes): After addition of biotinylated T4 (75 uL) and streptavidin-coated microparticles (35 uL), the still-free binding sites of the labeled antibody become occupied, with formation of an antibody-hapten complex. The entire complex is bound to the solid phase via interaction of biotin and streptavidin.
•The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier (0.4 second read frame).
•Results are determined via a calibration curve which is instrument-specifically generated by 2-point calibration and a master curve provided via the reagent bar code.

The provided document is a 510(k) summary for the Elecsys® T4 Assay, an in vitro diagnostic device for the quantitative determination of total thyroxine in human serum and plasma. This type of document is used to demonstrate substantial equivalence to a predicate device, not necessarily to set and meet acceptance criteria in the same way a clinical study for a novel therapeutic might.

However, we can infer "acceptance criteria" from the comparative performance tables against the predicate device, the Enzymun T4 Assay (K901346). The study aims to show that the Elecsys® T4 Assay performs comparably or better than the predicate device across various metrics.

Here's an attempt to structure the information based on your request, using the available data:

Acceptance Criteria and Device Performance Study for Elecsys® T4 Assay

The study presented in the 510(k) summary compares the performance of the Elecsys® T4 Assay to its predicate device, the Enzymun T4 Assay (K901346). The "acceptance criteria" are implied by the performance characteristics of the predicate device, with the new device aiming to demonstrate comparable or improved performance.

1. Table of Acceptance Criteria (Implied) and Reported Device Performance

Analysis of Performance vs. Implied Criteria:

• Precision: The Elecsys® T4 Assay achieved identical %CVs for both Within-Run and Total precision at comparable control levels as the predicate device.
• Lower Detection Limit: The Elecsys® T4 Assay demonstrated a significantly lower detection limit (0.23 µg/dL) compared to the predicate (0.6 µg/dL), indicating improved sensitivity.
• Linearity: The Elecsys® T4 Assay showed a comparable linear range, slightly wider at the lower end, with the same ±10% deviation tolerance.
• Method Comparison: While both devices were compared against the Enzymun-Test® T4, the Elecsys® T4 had a correlation coefficient (r=0.947) against the predicate from a larger sample size (N=196), which is lower than the predicate's own correlation (r=0.996) against the same Enzymun-Test® T4 from a smaller sample size (N=78). This suggests the predicate had very high agreement with itself when tested, while the Elecsys® T4, though showing good correlation, was not as tightly correlated with the predicate as the predicate was with itself.
• Interfering Substances: For most interfering substances, the Elecsys® T4 showed comparable or slightly different non-interference concentrations. Notably, it showed lower tolerance for Bilirubin and Biotin compared to the predicate, but higher tolerance for Lipemia.
• Specificity (% Cross-reactivity): The Elecsys® T4 showed similar cross-reactivity for L-T4 and D-T4. It demonstrated lower cross-reactivity for L-T3, D-T3, 3-iodo-L-tyrosine, and 3,5-diiodo-L-tyrosine, indicating improved specificity for T4 over these related compounds. However, it had a higher cross-reactivity for tetraiodo-thyroacetic acid.

2. Sample Size and Data Provenance

• Precision:
  • For the Elecsys® T4 Assay: N=60 for Control 1 and Control 2 at different levels.
  • For the Enzymun T4 Assay: N=120 for Low and Mid levels, N=118 for High level.
• Method Comparison:
  • Elecsys® T4 Assay: N=196 samples.
  • Enzymun T4 Assay (predicate's self-comparison): N=78 samples.
• Data Provenance: Not explicitly stated. Given it's a 510(k) submission by Boehringer Mannheim Corporation, the data would likely originate from internal studies or contract research organizations involved in the device's development and validation, likely in the US or Europe. It's a retrospective analysis of collected samples for performance evaluation.

3. Number of Experts and Qualifications for Ground Truth

Not applicable for this type of in vitro diagnostic device study. The "ground truth" for quantitative assays is typically established by reference methods or validated comparative assays, not by expert consensus on interpretations.

4. Adjudication Method for the Test Set

Not applicable. This is a quantitative assay comparison, not an imaging or clinical decision-making study requiring adjudication of interpretations.

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

Not applicable. This is an in vitro diagnostic device evaluating analytical performance, not a study involving human readers' interpretation (with or without AI assistance) of diagnostic cases.

6. Standalone Performance Study

Yes, the data provided for the "Elecsys® T4" column represents the standalone performance of the algorithm (analytical assay) in determining total thyroxine levels. The comparison made to the "Enzymun T4" column establishes its performance relative to a predicate device, which is a form of standalone evaluation against an accepted standard.

7. Type of Ground Truth Used

The "ground truth" for analytical performance studies like this is established by:

• Reference Methods: For assay standardization, "GC/MS Gas Chromatography/Mass Spectrometry" is mentioned for both devices, indicating a high-accuracy reference method.
• Comparative Assay: The predicate device itself (Enzymun T4 Assay) serves as a comparative "ground truth" for demonstrating substantial equivalence, meaning the new device's results align closely with an established and legally marketed device. The "Enzymun-Test® T4" mentioned in method comparison is likely the predicate or a closely related assay used as the comparative standard.

8. Sample Size for the Training Set

No specific "training set" is mentioned in the context of machine learning or AI models, as this device is a traditional immunoassay. The development and optimization of the assay would involve various experiments and optimizations, but not a distinct "training set" in the AI sense.

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

Not applicable, as there isn't a "training set" in the context of an AI/ML model for this device. The assay development would rely on chemical principles, reagent optimization, and calibration against known standards (e.g., those standardized by GC/MS).

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