(74 days)
The Dimension Vista™ Free Thyroxine Flex® reagent cartridge (FT4) is an in-vitro diagnostic test for the quantitative measurement of Free thyroxine in human serum and plasma.
The Dimension Vista™ LOCI I Calibrator is an in-vitro diagnostic product intended for the calibration of Thyroid Stimulating Hormone (TSH), Free Triodothyronine (FT3), and Free Thyroxine (FT4).
The Dimension Vista™ Free Thyroxine Flex® reagent cartridge (FT4) is a device intended to measure Free (not protein bound) thyroxine (thyroid hormone) in serum and 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 disease.
The Dimension Vista™ LOCI I Calibrator is a device intended for medical purposes for use in a the Dithenston + Iba - Dints of reference that are used in the determination of values in the test are creating of Free Thyroxine (FT4), Free Triiodothyronine (FT3), and Thyroid Stimulating Hormone (TSH) in human specimens.
The FT4 method is a homogenous, sequential, chemiluminescent immunoassay based on Luminescent Oxygen Channeling Immunoassay (LOCI™) technology. The LOCI™ reagents include two latex bead reagents and a biotinylated anti-T4 mouse monoclonal antibody. The first bead reagent (Chemibeads) is coated with triiodothyronine (T3), a naturally occurring, weaker binding analog of T4. and contains chemiluminescent dye. The second bead reagent (Sensibeads) is coated with streptavidin and contains a photosensitizer dye. In a first step, sample is incubated with biotinylated antibody which allows T4 from the sample to saturate a fraction of the biotinylated antibody that is directly related to the free T4 concentration. In a second step, T3 chemibeads are added and form bead/ biotinylated antibody immunocomplexes with the non-saturated fraction of the biotinylated antibody. Sensibeads are then added and bind to the biotin to form bead pair immunocomplexes. When illuminated by light at 680 nm, sensibeads convert dissolved oxygen in the reaction solution into the singlet oxygen form ('O2). In the bead pairs, the singlet oxygen diffuses ("channels") into chemibeads, triggering a chemiluminescent reaction. The resulting chemiluminescent signal is measured at 612 nm and is an inverse function of the concentration of free T4 in the sample.
The Dimension Vista™ LOCI I Calibrator is a three level, liguid, multi-analyte product. This product's matrix is bovine serum albumin and it contains buffer, stabilizer and preservatives. Level A is a zero level, while levels B and C contain human thyroxine, triodothyronine and thyroid stimulating hormone. Values are assigned to the calibrator from a masterpool that is traceable through a patient correlation study to an existing comparative method for FT3 and FT4. The TSH value is referenced to the WHO standard, 2nd IRP 80/588, and confirmed with the 3rd IS 81/565.
Here's an analysis of the provided text to extract the requested information about the acceptance criteria and the supporting study for the Dimension Vista™ Free Thyroxine Flex® reagent cartridge (FT4) and Dimension Vista™ LOCI 1 Calibrator:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implicit) | Reported Device Performance (Dimension Vista™ FT4 vs. ADVIA Centaur FrT4) |
|---|---|
| Strong linear correlation | Correlation Coefficient (r) = 0.983 |
| Slope close to 1 | Slope = 1.03 |
| Intercept close to 0 | Intercept = 0.02 |
Note on Acceptance Criteria: The document does not explicitly state quantitative acceptance criteria (e.g., "r must be > X", "slope must be within Y", etc.). The acceptance is implicitly based on achieving "substantial equivalence" through method comparison that demonstrates a strong clinical correlation to the predicate device. The presented correlation statistics (slope, intercept, correlation coefficient) are the reported performance that met this implicit acceptance of substantial equivalence.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: 108 clinical patient samples.
- Data Provenance: The data refers to "clinical patient samples," implying human samples. The country of origin is not specified but is almost certainly the USA, given that the submission is to the FDA from a US-based company (Dade Behring Inc., Newark, DE). The study is retrospective in the sense that the samples were already collected and then analyzed by both methods.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This information is not provided in the document. For in-vitro diagnostic (IVD) devices like this, the "ground truth" for method comparison is typically the measurement obtained by the predicate device (ADVIA Centaur FrT4 assay), which is itself a legally marketed and presumably validated device. Therefore, expert consensus on individual patient results isn't typically established in the same way as for, say, an imaging AI product diagnosing disease. The predicate device's measurement serves as the standard.
4. Adjudication Method for the Test Set
This information is not applicable/provided for this type of IVD method comparison study. Adjudication methods (like 2+1, 3+1) are typically used in studies where human experts are making subjective assessments that need to be reconciled to establish a consensus ground truth, such as in imaging studies. For a quantitative measurement comparison between two devices, the "ground truth" is typically the measurement from the established predicate method, and no human adjudication of individual results against a "true" disease state is described.
5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size
No, a Multi Reader Multi Case (MRMC) comparative effectiveness study was not done. This type of study assesses how AI assistance impacts human reader performance (e.g., radiologists interpreting images). The study described here is a direct comparison of the new device's quantitative output (Free Thyroxine levels) against a predicate device's quantitative output, not an assessment of human interpretation with or without AI.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, a standalone performance evaluation was done. The study directly compares the performance of the Dimension Vista™ Free Thyroxine Flex® reagent cartridge (the "algorithm/device only") to the predicate device (ADVIA Centaur FrT4 assay). This is a direct measurement of the device's output, without human intervention in the result generation or interpretation that would typically define "human-in-the-loop" for device performance. The device produces a quantitative measurement, and its accuracy is assessed against the predicate's measurement.
7. The Type of Ground Truth Used
The ground truth used for the comparison study was the measurements obtained from the predicate device (ADVIA Centaur FrT4 assay). The study aimed to show "substantial equivalence" of the new device's measurements to those of an already legally marketed, established method.
8. The Sample Size for the Training Set
The document does not provide information on the sample size used for the training set. This is a 510(k) submission focused on the analytical performance for equivalence, not a detailed description of the device's internal development and training (if any 'machine learning' type training were involved, which is unlikely for this type of traditional immunoassay).
9. How the Ground Truth for the Training Set Was Established
The document does not provide information on how the ground truth for a training set was established, as details about a training set are not mentioned. For the calibrator, the document states: "Values are assigned to the calibrator from a masterpool that is traceable through a patient correlation study to an existing comparative method for FT3 and FT4." This describes the calibration process, which uses reference materials traceable to comparative methods, rather than a "training set" for an AI algorithm.
§ 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.