(98 days)
The LIAISON® Testosterone xt is a direct, competitive, chemiluminescence immunoassay (CLIA) intended for the quantitative determination of testosterone in human serum and EDTA plasma on the LIAISON® XL Analyzer. The assay is intended for in vitro diagnostic use.
Measurement of testosterone is used in the diagnosis and treatment of disorders involving the male sex hormones (androgens), including primary and secondary hypogonadism, delayed or precocious puberty, impotence in males and, in females hirsutism (excessive hair) and virilization (masculinization) due to tumors, polycystic ovaries, and adrenogenital syndromes.
The test has to be performed on the LIAISON® XL Analyzer.
The LIAISON® Testosterone xt assay's method for quantitative determination of testosterone is a direct, competitive, chemiluminescence immunoassay (CLIA). Specific antibody to testosterone is bound to magnetic particles (solid phase) and testosterone is linked to an isoluminol derivative. During the incubation, testosterone is dissociated from its binding protein and competes with labeled testosterone for binding sites on the antibody. After the incubation, the unbound material is removed with a wash cycle. Subsequently, the starter reagents are added and a flash chemiluminescent reaction is initiated. The light signal is measured by a photomultiplier as relative light units (RLU) and is inversely proportional to the concentration of testosterone present in calibrators, controls, or samples.
The LIAISON® Testosterone xt is an in vitro diagnostic device consisting of reagents provided in individual compartments within a plastic container called the Reagent Integral. The components provided in the unitized Reagent Integral include: PMP (paramagnetic particles), conjugate and assay buffer. All reagents in the integral are supplied ready to use. The assay configuration for the LIAISON® Testosterone xt allows for the performance of 100 tests.
The two-point calibrators are provided in the same kit box, but separate from the Reagent Integral. The two-point calibrators are supplied ready to use.
The LIAISON® Testosterone xt assay is performed on the LIAISON® XL Analyzer (Model 10050; originally FDA cleared under K103529), a fully automated system with continuous loading combining the chemiluminescence technology with magnetic microparticles as the solid phase.
Here's a breakdown of the acceptance criteria and study information for the LIAISON® Testosterone xt device, extracted from the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Characteristic | Acceptance Criteria (Predicate Device) | Reported Device Performance (LIAISON® Testosterone xt) |
|---|---|---|
| Assay Measuring Range | 0.16 - 15.0 ng/mL | Extended: 0.024 – 15.0 ng/mL |
| Limit of Blank (LoB) | ≤ 0.031 ng/mL | Improved: ≤ 0.005 ng/mL |
| Limit of Detection (LoD) | 0.098 ng/mL | Improved: 0.010 ng/mL |
| Limit of Quantitation (LoQ) | 0.160 ng/mL | Improved: 0.024 ng/mL |
| Method Comparison | y = 0.9390x – 0.1002 (vs. commercially available immunoassay) | |
| 95% CI for slope: 0.92 to 0.96 | ||
| 95% CI for intercept: -1.88 to 1.80 ng/dL | y = 0.99x – 1.77 ng/dL (vs. CDC HoSt Testosterone RMP ID-LC-MS/MS values) | |
| 95% CI for slope: 0.97 to 1.02 | ||
| 95% CI for intercept: -3.22 to -0.35 ng/dL | ||
| Precision (Total/Across Lots %CV) | 7.9% – 14.0% | Improved: 3.5% – 7.9 % |
| Linearity (Serum) | Observed Analyte = 0.9942x – 16.062; R² = 0.9959 | Observed Analyte = 0.995x + 0.0346; R² = 0.9928 |
| Linearity (SST Serum) | Observed Analyte = 1.0188x - 14.531; R² = 0.9965 | Observed Analyte = 1.0225x - 57.853; R² = 0.9914 |
| Linearity (EDTA plasma) | Observed Analyte = 1.0057x - 13.029; R² = 0.9913 | Observed Analyte = 1.0337x - 31.889; R² = 0.9955 |
| Recovery (Mean %) | 97% | 99% |
| Recovery (Range %) | 91% - 105% | 93% - 105% |
| Open Use Stability: Reagent Integral | 4 weeks | Extended: 8 weeks |
| Open Use Stability: Calibrators | 4 weeks | Extended: 8 weeks |
| Calibration Curve Stability | 7 days | Extended: 28 days |
2. Sample Size for the Test Set and Data Provenance
The provided document does not explicitly state the sample sizes used for each specific test (e.g., method comparison, precision, linearity, recovery). It only summarizes the results in "Table 6-2: Comparison to Predicate Device" and refers to "verification and validation activities" without detailing the exact number of samples for each.
The data provenance is not specified in terms of country of origin. The studies appear to be retrospective analyses of device performance characteristics, as they involve testing the LIAISON® Testosterone xt against existing methods or conditions to demonstrate equivalence and improved performance over the predicate device.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
This information is not explicitly provided in the document. For the "Method Comparison," it refers to "commercially available immunoassay" and "CDC HoSt Testosterone RMP ID-LC-MS/MS values." The latter, CDC HoSt Testosterone RMP ID-LC-MS/MS, likely represents a highly accurate and standardized reference method, which serves as a widely accepted ground truth in laboratory medicine, rather than relying on individual expert consensus for each measurement. No human experts are mentioned for ground truth establishment.
4. Adjudication Method for the Test Set
No explicit adjudication method is mentioned. The studies focus on direct quantitative analytical performance comparisons rather than subjective human interpretation.
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
This is not applicable. The LIAISON® Testosterone xt is an in vitro diagnostic device, specifically a chemiluminescence immunoassay (CLIA), for the quantitative determination of testosterone. It is an automated laboratory test, not an AI-assisted diagnostic imaging or interpretation tool that involves human readers. Therefore, an MRMC comparative effectiveness study involving human readers and AI is not relevant to this device.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, this is effectively a standalone device performance study. The LIAISON® Testosterone xt is an automated system where the measurement of testosterone is performed by the analyzer (LIAISON® XL Analyzer) without human intervention in the analytical process itself. The performance metrics (LoB, LoD, LoQ, precision, linearity, recovery) are all measures of the algorithm's and instrument's direct analytical capability.
7. The Type of Ground Truth Used
The ground truth used for method comparison was:
- For the predicate device: A "commercially available immunoassay."
- For the LIAISON® Testosterone xt: "CDC HoSt Testosterone RMP ID-LC-MS/MS values." This is a highly accurate, reference method-based measurement, representing the gold standard for testosterone quantification. Other ground truths were established by controlled experiments for limits (e.g., dilution series for LoB, LoD, LoQ), spiked samples for recovery, and replicated measurements for precision.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning or AI. This device is an immunoassay, not an AI model that requires a distinct training phase with a labeled dataset in the typical sense. Its development would involve analytical validation using various samples to optimize reagent formulation, assay parameters, and calibration, but not as a machine learning training set.
9. How the Ground Truth for the Training Set was Established
As explained above, there is no "training set" in the machine learning sense for this immunoassay. The development and validation of an immunoassay involve:
- Reference materials: Use of certified reference materials or reference methods (like ID-LC-MS/MS) to establish accurate values for calibrators and controls.
- Spiked samples: Samples with known concentrations of testosterone added.
- Clinical samples: Testing a range of patient samples representing the intended use population, comparing results to established methods.
- Statistical analysis: Extensive statistical methods are used during development and validation to ensure accuracy, precision, linearity, and other performance characteristics.
§ 862.1680 Testosterone test system.
(a)
Identification. A testosterone test system is a device intended to measure testosterone (a male sex hormone) in serum, plasma, and urine. Measurement of testosterone are used in the diagnosis and treatment of disorders involving the male sex hormones (androgens), including primary and secondary hypogonadism, delayed or precocious puberty, impotence in males and, in females hirsutism (excessive hair) and virilization (masculinization) due to tumors, polycystic ovaries, and adrenogenital syndromes.(b)
Classification. Class I.