(14 days)
The ACCESS® Total T3 Assay is a paramagnetic particle, chemiluminescent immunoassay for the quantitative determination of triiodothyronine levels in human serum, using the ACCESS® Immunoassay System. The clinical importance of total serum T3 determination is in the diagnosis of thyroid disorders. Elevated concentrations of T3 can be found in Grave's disease, and most other classical causes of hyperthyroidism. Decreased concentrations occur in primary hypothyroid diseases such as Hashimoto's thyroiditis and neonatal hypothyroidism or secondary hypothyroidism due to defects at the hypothalamo-hypophyseal level.
The ACCESS® Total T3 reagents and the ACCESS® Immunoassay Analyzer comprise the ACCESS® Immunoassay System for the quantitative determination of triiodothyronine in human serum.
Here's an analysis of the provided text, focusing on the acceptance criteria and the study that proves the device meets them:
Acceptance Criteria and Device Performance for ACCESS® Total T3 Assay
This submission describes the ACCESS® Total T3 assay, an in vitro diagnostic device for the quantitative determination of triiodothyronine (T3) levels in human serum. The studies presented demonstrate analytical performance, proving substantial equivalence to a predicate device.
1. Table of Acceptance Criteria and Reported Device Performance
The documentation does not explicitly state pre-defined acceptance criteria in terms of numerical thresholds for precision, accuracy, or correlation. Instead, it presents the results of studies and implies that these results are considered acceptable for demonstrating substantial equivalence to the predicate device. For the purpose of this analysis, the reported statistical results from the "Summary of Studies" section are presented as the "reported device performance." The implied acceptance is that these values demonstrate performance comparable to or adequate for the intended use and are similar to a legally marketed predicate device.
| Performance Metric | Reported Device Performance | Implied Acceptance Criteria (Based on Substantial Equivalence) |
|---|---|---|
| Precision | ||
| Within-run CV | 3.22% CV (high control) to 5.22% CV (low control) | Clinically acceptable variability for T3 measurement; comparable to predicate. |
| Total Imprecision CV | 4.74% CV (high control) to 9.12% CV (low control) | Clinically acceptable variability for T3 measurement over time; comparable to predicate. |
| Accuracy (Recovery) | ||
| Dilution Recovery | 85.6% to 107.7% recovery | Within a clinically acceptable range (e.g., 80-120% or 90-110%) for T3 assays. |
| Spiking Recovery | 87.7% to 112.1% recovery | Within a clinically acceptable range (e.g., 80-120% or 90-110%) for T3 assays. |
| Correlation | r = 0.978, y = 1.020x + 0.077 (vs. Ciba Corning ACS™ T3) | Strong correlation (r > 0.95) and minimal bias / proportional error (slope near 1, intercept near 0) with a predicate device. |
| Analytical Sensitivity | 0.1 ng/ml (lowest detectable level distinguishable from zero with 95% confidence) | Clinically relevant lower limit of detection for T3, allowing for diagnosis of low T3 states. |
2. Sample Size Used for the Test Set and Data Provenance
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Sample Size for Test Set:
- Precision Studies: Not explicitly stated for each level (low, mid, high control), but typically involves replicates over several runs/days.
- Accuracy (Recovery) Studies: "two patient samples" for dilution recovery and "two patient samples" for spiking recovery. This is a very small sample size for these studies.
- Correlation Study: 153 samples.
- Analytical Sensitivity: Not explicitly stated but usually involves multiple measurements of zero calibrator and low-level samples.
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Data Provenance: The document does not specify the country of origin for the patient samples. It also does not explicitly state whether the studies were retrospective or prospective, though performance studies for a 510(k) submission are typically prospective, conducted under controlled conditions to evaluate the new device's analytical capabilities.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
N/A. This device is an in vitro diagnostic assay for a quantitative analyte (Total T3). The "ground truth" for the test set is established by the reference measurement method (the predicate device for correlation) or by the inherent properties of the controls and spiked/diluted samples. There are no human experts involved in establishing a "ground truth" in the way one would for image interpretation or disease diagnosis.
4. Adjudication Method for the Test Set
N/A. No adjudication method is applicable as this is not a subjective interpretation task requiring expert consensus.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not done. This type of study is relevant for diagnostic devices that involve human interpretation (e.g., radiologists reading images) and would assess the impact of an AI tool on reader performance. The ACCESS® Total T3 assay is an automated quantitative immunoassay.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, the studies presented are essentially "standalone" performance evaluations. The device (ACCESS® Immunoassay System and reagents) outputs a quantitative T3 value, and the performance metrics (precision, accuracy, correlation, sensitivity) are evaluated based on these automated outputs. There is no human-in-the-loop component for interpreting the result itself, though human operators are involved in running the assay.
7. The Type of Ground Truth Used
- Precision: Statistical variability of repeated measurements on control materials or patient samples. The "ground truth" is the inherent stability and reproducibility of the assay.
- Accuracy:
- Dilution/Spiking Recovery: The "ground truth" is the expected concentration based on the known dilution factor or amount spiked.
- Correlation: The "ground truth" is the measurement obtained from the legally marketed predicate device (Ciba Corning ACS™ T3 assay).
- Analytical Sensitivity: The "ground truth" is typically defined by statistical methods (e.g., 95% confidence interval of zero calibrator measurements).
8. The Sample Size for the Training Set
N/A. The ACCESS® Total T3 assay is a biochemical immunoassay, not a machine learning or AI-based algorithm that requires a "training set" in the conventional sense. The assay's performance characteristics are inherent to its chemical and biological components and the instrument's design.
9. How the Ground Truth for the Training Set Was Established
N/A. As there is no "training set" for this type of device, this question is not applicable.
§ 862.1710 Total triiodothyronine test system.
(a)
Identification. A total triiodothyronine test system is a device intended to measure the hormone triiodothyronine in serum and plasma. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases such as hyperthyroidism.(b)
Classification. Class II. This device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 862.9.