(29 days)
HemosIL von Willebrand Factor Activity is an automated latex enhanced immunoassay intended for the in vitro diagnostic quantitative determination of von Willebrand Factor Activity (VWF Activity) in human citrated plasma on IL Coagulation Systems.
The VWF Activity kit is a latex particle enhanced immunoturbidimetric assay to quantify VWF Activity in plasma. The activity of VWF is determined by measuring the increase of turbidity produced by the agglutination of the latex reagent. A specific anti-VWF monoclonal antibody adsorbed onto the latex reagent, directed against the platelet binding site of VWF (Glycoprotein Ib receptor), reacts with the VWF of patient plasma. The degree of agglutination is directly proportional to the activity of VWF in the sample and is determined by measuring the decrease of transmitted light caused by the aggregates.
Here's a summary of the acceptance criteria and study details for the HemosIL von Willebrand Factor Activity device, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The submission does not explicitly state pre-defined acceptance criteria in terms of specific thresholds for correlation coefficients or precision values. Instead, it presents performance data and asserts substantial equivalence to a predicate device. We can infer that the reported performance values were considered acceptable for demonstrating substantial equivalence.
| Performance Metric | Acceptance Criteria (Inferred) | Reported Device Performance |
|---|---|---|
| Method Comparison (vs. Predicate Device) | Strong correlation (high 'r' value), slope near 1, intercept near 0 | ACL 9000: |
| Slope: 0.832 | ||
| Intercept: 4.782 | ||
| r: 0.972 | ||
| Precision (Within-run CV%) | Low variability | ACL 9000: |
| Normal Control: 2.7% | ||
| Special Test Controls Level 1: 4.6% | ||
| Special Test Controls Level 2: 7.5% | ||
| Precision (Total CV%) | Low variability | ACL 9000: |
| Normal Control: 4.9% | ||
| Special Test Controls Level 1: 9.0% | ||
| Special Test Controls Level 2: 8.7% |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size (Method Comparison): 108 citrated plasma samples.
- Sample Size (Precision): Not explicitly stated how many individual samples composed the "three levels of control plasma," but a single sample generated data over "multiple runs."
- Data Provenance: Not explicitly stated (e.g., country of origin). The data appears to be from a prospective study conducted for the submission since it's presented as "Method Comparison studies on an ACL 9000" and "Precision... assessed over multiple runs." No indication of retrospective data.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
- Not Applicable. This device is an in-vitro diagnostic test for quantitative determination of a biomarker, not an imaging device or one requiring expert interpretation of results to establish ground truth in the traditional sense. The "ground truth" for the method comparison was the result obtained from the predicate device. For precision, the ground truth was the mean value determined by the device itself.
4. Adjudication Method for the Test Set
- Not Applicable. As explained above, this type of device does not involve expert adjudication for its performance evaluation in this context. The comparison is against an established method and the device's own internal consistency.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, and its effect size
- No. An MRMC study is not relevant for this type of in-vitro diagnostic device. These studies typically compare human reader performance with and without AI assistance for tasks like image interpretation.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
- The performance data presented (method comparison and precision) is inherently standalone performance of the device (automated latex enhanced immunoassay) on an IL Coagulation System. There is no human-in-the-loop aspect to the VWF Activity measurement itself for interpretation or modification of results, beyond the operator loading samples and running the instrument.
7. The Type of Ground Truth Used
- Method Comparison: The results obtained from the predicate device (Shield Von Willebrand Factor Activity ELISA) served as the comparative 'ground truth' or reference for assessing the new device's performance.
- Precision: The mean value of the device's own measurements for control plasmas was used to assess precision (variability around that mean).
8. The Sample Size for the Training Set
- Not Applicable. This device is described as an "automated latex enhanced immunoassay" which uses specific monoclonal antibodies. It is a biochemical assay and does not appear to involve machine learning or AI algorithms that require a separate "training set" of data in the typical sense. Its performance is based on the chemical reactions and optical detection, not an algorithm trained on a dataset.
9. How the Ground Truth for the Training Set was Established
- Not Applicable. As explained above, there is no indication of a training set as would be found in AI/ML applications. The device's operational characteristics are intrinsic to its chemical and optical design.
§ 864.7290 Factor deficiency test.
(a)
Identification. A factor deficiency test is a device used to diagnose specific coagulation defects, to monitor certain types of therapy, to detect coagulation inhibitors, and to detect a carrier state (a person carrying both a recessive gene for a coagulation factor deficiency such as hemophilia and the corresponding normal gene).(b)
Classification. Class II (performance standards).