(49 days)
For the in vitro quantitative determination of total triiodothyronine (T3) in human serum and plasma.
The Elecsys® T3 employs a competitive test principle with polyclonal antibodies directed against T3 and with streptavidin microparticles and electrochemiluminescence detection. Total duration of assay: 18 minutes.
• 1st Incubation: Sample (30 µl) and specific anti-T3 antibodies labeled with a ruthenium complex together with ANS to release T3 from serum.
• 2nd Incubation: After the addition of streptavidin-coated microparticles and biotinylated T3, 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.
• 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.
Here's a summary of the acceptance criteria and study information for the Elecsys T3 device, based on the provided 510(k) summary:
The document does not explicitly state "acceptance criteria" in a pass/fail format, but rather presents performance characteristics of the new device (Elecsys T3) and compares them to a predicate device (Enzymun-Test® T3). The implicit acceptance criteria appear to be substantial equivalence, demonstrated by similar performance characteristics.
1. Table of Acceptance Criteria and Reported Device Performance
| Feature | Elementys T3 Performance (New Device) | Predicate Device (Enzymun-Test® T3) Performance | Implicit Acceptance Criteria (Demonstrates Substantial Equivalence if similar) |
|---|---|---|---|
| Precision | |||
| Within-run % CV | PC U1: 4.1%, PC U2: 3.5%, HS1: 3.6%, HS2: 4.2%, HS3: 5.3% | 1: 2.9%, 2: 1.6%, 3: 1.7% | Similar or better precision (lower % CV) across different sample concentrations. While some Elecsys T3 values are higher, they are generally in the same range, suggesting acceptable performance. |
| Total run % CV | PC U1: 4.8%, PC U2: 4.1%, HS1: 5.4%, HS2: 4.7%, HS3: 5.4% | 1: 4.7%, 2: 2.2%, 3: 2.8% | Similar or better precision (lower % CV) across different sample concentrations. |
| Sensitivity | Lower Detection Limit: 0.3 nmol/l (0.19 ng/ml) | Lower Detection Limit: 0.46 nmol/l (0.3 ng/ml) | Sensitivity should be comparable or better. Elecsys T3 demonstrates better (lower) detection limit. |
| Assay Range | 0.3 - 10.00 nmol/l (0.19 - 6.51 ng/ml) | 0.46 - 9.22 nmol/l (0.3 - 6.0 ng/ml) | Assay range should be comparable. Elecsys T3 offers a slightly broader range at the upper end and a lower detection limit. |
| Method Comparison | vs. Enzymun-Test T3 (Cat. # 1360868): | ||
| Least Squares: N = 300, y = -0.35 + 1.18x, r = 0.957 | |||
| Passing/Bablok: N = 300, y = -0.56 + 1.26x, r = 0.957 |
vs. Enzymun-Test T3 (Cat. # 1135287):
Least Squares: N = 55, y = 1.13x + 0.02, r = 0.994 | (This section compares the new device to the predicate, so the predicate itself isn't a comparison target here, but the data it generated is used for comparison) | Correlation coefficients (r) close to 1, and slope (x) close to 1 with intercept (y) close to 0, indicating strong agreement between the new device and the predicate. The reported 'r' values of 0.957 and 0.994 suggest very good correlation. |
| Interfering Substances | Hemoglobin: 1 g/dl
Lipemia: 1500 mg/dl
Bilirubin: 25 mg/dl
Biotin: 20 ng/ml | Hemoglobin: 1 g/dl
Lipemia: 1250 mg/dl
Bilirubin: 65 mg/dl
Biotin: 50 ng/ml | Acceptable levels of interference for common substances. Elecsys T3 shows comparable or improved tolerance for some interferents (e.g., lipemia) and slightly lower tolerance for others (bilirubin, biotin), but within a clinically acceptable range as demonstrated by the predicate. |
| Specificity (% cross-reaction) | D-T3: 98.9%, L-T4: 0.115%, D-T4: 0.115%, L-rT3: 0.007%, L-T2: 0.998%, 3,3',5-tri-iodothyroacetic acid: 106.4%, 3,3',5,5'-tetra-iodothyroacetic acid: 0.007% | D-T3: 100%, L-T4: 0.16%, D-T4: 0.07%, L-rT3: 0.04%, L-T2: 1.0%, 3,3',5-tri-iodothyroacetic acid: 7.5%, 3,3',5,5'-tetra-iodothyroacetic acid: 0.01% | High specificity for T3 and low cross-reactivity with related substances, comparable to the predicate. The values are very close, indicating similar performance. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly define a "test set" in the context of an AI/algorithm-driven device. Instead, it describes performance characteristics determined through various studies.
- Precision Studies (NCCLS modified EP5-T2 for Elecsys T3, Modified NCCLS "Midi" EP3-T for Enzymun-Test T3):
- Elecsys T3 Sample Size (N): 60 for each of the 5 samples (PC U1, PC U2, HS1, HS2, HS3). This suggests 60 replicates or measurements per sample, likely conducted over multiple runs/days as indicated by "total run % CV".
- Enzymun-Test® T3 Sample Size (N): 118, 120, 117 for 3 different samples.
- Method Comparison Studies:
- Elecsys T3 vs. Enzymun-Test T3 (Cat. # 1360868): N = 300
- Elecsys T3 vs. Enzymun-Test T3 (Cat. # 1135287): N = 55
- Data Provenance: Not explicitly stated, but clinical studies for such devices typically involve human serum and plasma samples. The specific country of origin or whether the data was retrospective or prospective is not provided. It's common for these types of studies to be prospective, collecting samples specifically for the validation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This device is an in vitro diagnostic (IVD) assay for quantitative determination of a hormone, not an imaging or diagnostic algorithm that relies on expert interpretation for ground truth. Therefore, there were no "experts" establishing ground truth in the traditional sense for a test set typically associated with AI/ML devices. The "ground truth" for quantitative assays is established by the reference method or by comparing against a well-established predicate device, which is what was done here.
4. Adjudication Method for the Test Set
Not applicable. As described above, this is a quantitative assay, and ground truth is based on measurements and comparison to a predicate device, not expert adjudication of cases.
5. 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 device is an in vitro diagnostic analyzer (an automated assay), not an AI-powered image analysis or diagnostic aid requiring human readers for interpretation. Therefore, an MRMC study or assessment of human reader improvement with AI assistance is not relevant.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
The device itself is a standalone algorithm/assay in its operation. The Elecsys T3 system performs the measurement and provides a quantitative result. There is no human "in the loop" during the primary measurement process beyond loading samples and reagents, and interpreting the final quantitative value. The performance characteristics described (precision, sensitivity, assay range, method comparison, interfering substances, specificity) are all measures of its standalone analytical performance.
7. The Type of Ground Truth Used
The ground truth used for performance evaluation is primarily:
- Reference measurements/Predicate Device Comparison: The performance of the Elecsys T3 was compared directly against a legally marketed predicate device, the Enzymun-Test® T3. This comparison (method comparison studies) serves as the primary ground truth for demonstrating substantial equivalence.
- Defined concentrations/standards: For precision, sensitivity, and assay range, the "ground truth" comes from precisely prepared samples with known concentrations (e.g., control samples, diluted samples).
- Interfering substances/specificity panels: For these studies, the ground truth is the presence of known interfering substances or related compounds at specific concentrations, allowing the device's response to be assessed.
8. The Sample Size for the Training Set
The document does not mention a "training set" in the context of machine learning or AI. This is a traditional IVD device, not an AI/ML diagnostic. The development of such assays involves extensive R&D and optimization, but not typically a "training set" like in deep learning.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no "training set" in the AI/ML sense for this traditional IVD device. The development process would rely on biochemical principles, empirical optimization, and validation against established reference methods or predicate devices.
§ 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.