(28 days)
The ARCHITECT Free T4 (FT4) assay is a Chemiluminescent Microparticle Immunoassay (CMIA) for the quantitative determination of free thyroxine (Free T4) in human serum and plasma.
ARCHITECT Free T4 (FT4) assay is to be used as an aid in the assessment of thyroid status.
The ARCHITECT Free T4 assay is a two-step immunoassay for the quantitative determination of free thyroxine (Free T4) in human serum and plasma using CMIA technology with flexible assay protocols, referred to as Chemiflex.
In the first step, sample and anti-T4 coated paramagnetic microparticles are combined. Free T4 (unbound) present in the sample binds to the anti-T4 coated microparticles. After washing, Ts acridinium-labeled conjugate is added to create a reaction mixture. Following another wash cycle, pre-trigger and trigger solutions are added to the reaction mixture. The resulting chemiluminescent reaction is measured as relative light units (RLUs). An inverse relationship exists between the amount of Free T4 in the sample and the RLUs detected by the ARCHITECT i System optics.
The provided text describes a 510(k) premarket notification for a modification to the ARCHITECT Free T4 assay, not a study proving device meets acceptance criteria in the context of AI/ML or comparative effectiveness. The device is an in-vitro diagnostic (IVD) test, and the information requested about AI/ML models, human readers, and ground truth types (pathology, outcomes data) is not applicable to this type of device or documentation.
However, I can extract the acceptance criteria and performance data related to the nonclinical performance verification for the modified ARCHITECT Free T4 assay, as presented in the document.
Acceptance Criteria and Reported Device Performance
The device under review is an in-vitro diagnostic (IVD) assay, not an AI/ML device. Therefore, acceptance criteria and performance are based on analytical performance studies. The document states that the "device passed all of the tests based on pre-determined acceptance criteria." While the specific numerical acceptance criteria are not detailed in this summary, the types of tests performed and the general outcome are reported.
| Acceptance Criteria Category | Reported Device Performance |
|---|---|
| Limit of Blank/Detection/Quantitation | Device passed based on pre-determined acceptance criteria. |
| Precision (20-Day) | Device passed based on pre-determined acceptance criteria. |
| Precision at Limits of Measuring Interval | Device passed based on pre-determined acceptance criteria. |
| Accuracy by Correlation | Device passed based on pre-determined acceptance criteria. |
| Accelerated Life Testing (ALT) Stability | Device passed based on pre-determined acceptance criteria. |
| Reagent On Board Stability | Device passed based on pre-determined acceptance criteria. |
| Linearity | Device passed based on pre-determined acceptance criteria. |
1. Sample sized used for the test set and the data provenance:
The document does not specify the exact sample sizes used for each individual nonclinical performance study (Limit of Blank/Detection/Quantitation, Precision, Accuracy, Stability, Linearity). It also does not explicitly state the country of origin of the samples or if they were retrospective or prospective, though for IVD analytical performance, these would typically be control samples and patient samples collected for various analytical evaluations to represent the intended use population.
2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
Not applicable. For an immunoassay, the "ground truth" for analytical performance studies is established by the assay's ability to accurately and precisely measure the analyte (Free T4) in samples against known concentrations or reference methods, not by expert interpretation of images or clinical data.
3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:
Not applicable. Adjudication methods like 2+1 are used for expert consensus on subjective interpretations (e.g., radiology reads), which is not relevant for an IVD analytical performance study.
4. 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 IVD assay, not an AI/ML diagnostic tool involving human readers.
5. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
Not applicable. This is an IVD immunoassay, not an algorithm or AI model. Its performance is inherent to the assay chemistry and instrument.
6. The type of ground truth used:
For the analytical performance studies, the "ground truth" is established through:
- Known concentrations: For studies like linearity, limits, and precision, samples with known concentrations of Free T4 would be used.
- Reference methods/comparative methods: For accuracy by correlation, the results of the ARCHITECT Free T4 assay would be compared against a legally marketed predicate device (as referenced, K123379) or a recognized reference method.
7. The sample size for the training set:
Not applicable. This is an immunoassay, not an AI/ML model, so there is no "training set" in the computational sense. The development of the assay reagents and protocols is based on chemical and biological research and optimization.
8. How the ground truth for the training set was established:
Not applicable, as there is no "training set" in the context of an AI/ML model. The development of the assay components (reagents, microparticles, conjugate) and the associated manufacturing process enhancement (reduced microparticle percent solids) are validated through the nonclinical performance studies listed.
§ 862.1695 Free thyroxine test system.
(a)
Identification. A free thyroxine test system is a device intended to measure free (not protein bound) thyroxine (thyroid hormone) in serum or plasma. Levels of free thyroxine in plasma are thought to reflect the amount of thyroxine hormone available to the cells and may therefore determine the clinical metabolic status of thyroxine. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases.(b)
Classification. Class II.