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510(k) Data Aggregation
(72 days)
Enzygnost F1+2 (monoclonal) is an enzyme immunoassay for the quantitative determination of human prothrombin F1+2 in plasma. Measurement of F1+2 is used as an aid in the diagnosis, monitoring, and evaluation of acquired or hereditary blood coagulation disorders. It is indicated as an aid in assessing risk of thrombosis and in monitoring efficacy of anticoagulant therapy.
The Enzygnost™ F1+2 Test Kit is an enzyme immunoassay based on the sandwich principle in microtiter format utilizing monoclonal mouse antibodies. During the first incubation, the F1+2 antigen in the sample binds to F1+2 antibodies attached to the microtiter plate. After washing, peroxidase-conjugated antibodies to human prothrombin are bound to a free F1+2 determinant in a second reaction. The excess enzyme-conjugated antibodies are removed by washing; the bound enzyme activity is then determined. The enzymatic reaction between hydrogen peroxide and chromogen is terminated by the addition of dilute sulfuric acid. The color intensity, which is proportional to the concentration of F1+2, is determined photometrically and quantified by means of a calibration curve based on the standards included in the kit.
Here's an analysis of the provided information, structured to answer your questions about acceptance criteria and the supporting study for the Enzygnost™ F1+2 (monoclonal) device:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Correlation to Predicate Device | High correlation coefficient (target usually > 0.9) | 0.96 |
| Slope (vs. predicate) | Slope close to 1 | 0.265 (This indicates a significant difference in scale or measurement between the two devices and is not close to 1. However, the FDA found substantial equivalence, suggesting this difference was acceptable in the context of the device's function or that a conversion factor is implied. It's important to note the discrepancy if interpreting solely on a "close to 1" metric.) |
| Intercept (vs. predicate) | Intercept close to 0 | -29.378 (Similar to the slope, this indicates a bias between the two devices. The FDA's acceptance suggests this was deemed acceptable.) |
| Within-Run Precision (CV) | Low coefficient of variation (typical <= 10%) | 3.6% - 5.5% |
| Day-to-Day Precision (CV) | Low coefficient of variation (typical <= 15%) | 4.4% - 11.2% |
Note on Acceptance Criteria: The provided document does not explicitly state numerical acceptance criteria for correlation, slope, or intercept. These are inferred based on typical industry expectations for substantial equivalence studies comparing new devices to predicate devices. The FDA's clearance (K042687) indicates that the presented performance met their criteria for substantial equivalence to the predicate device despite the slope and intercept values.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: 190 patient samples.
- Data Provenance: The document does not specify the country of origin. The study was retrospective, as it involved "patient samples spanning the range of assay," implying pre-collected samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of information is generally not applicable to an in vitro diagnostic (IVD) device like the Enzygnost™ F1+2. The "ground truth" for this device is based on the quantitative measurement of a specific analyte (prothrombin fragment F1+2) using a laboratory method. The predicate device's results serve as the reference standard, rather than expert interpretation of images or clinical data. There are no "experts" establishing a ground truth in the way described for imaging or clinical decision support AI.
4. Adjudication Method for the Test Set
Not applicable. As described above, this is a quantitative measurement device, not one requiring expert adjudication of results. The comparison is statistical against a predicate device.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No. An MRMC study is relevant for devices that involve human interpretation, often in imaging. This device (Enzygnost™ F1+2) is an in vitro diagnostic test that provides a quantitative numerical output, not something a human "reads" in a subjective sense that would be improved by AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, in the context of an IVD. The performance metrics presented (correlation, precision) are for the device (the "algorithm") performing its function independently on samples. There is no human "in-the-loop" once the sample is loaded and the assay runs. The results are generated solely by the device.
7. The Type of Ground Truth Used
The "ground truth" for the test set was the results obtained from the predicate device, Enzygnost™ F1+2 micro test kit (K922934). This is a form of comparative reference standard or established assay performance.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" like one would describe for an AI/ML model. For an IVD like this, calibration curves are established using standards provided within the kit. The document mentions "a calibration curve based on the standards included in the kit." The number of samples used to establish these internal calibration standards is not specified but would be part of the manufacturer's internal validation, not typically detailed in 510(k) summaries unless specifically relevant to a new method of calibration.
9. How the Ground Truth for the Training Set Was Established
For IVD devices, the "ground truth" for training (i.e., calibration) is typically established using:
- Certified Reference Materials: Substances with a precisely known concentration of the analyte.
- Primary Calibrators: Highly pure substances with accurately assigned values.
- Traceability to Reference Measurement Procedures: Ensuring the calibration is linked to higher-order reference methods.
The document states, "quantified by means of a calibration cure based on the standards included in the kit," implying that the ground truth for calibration is based on these manufacturer-supplied, value-assigned standards, which are themselves derived from rigorous analytical methods. This is an internal manufacturing and quality control process rather than an external expert consensus panel.
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