(105 days)
The Phosphoplastin RL Prothrombin Time reagent is a liquid PT reagent containing thromboplastin derived from rabbit brain and calcium ions for use in the determination of Prothrombin Time (PT) and related coagulation procedures. The PT test is a one-stage test used in routine patient screening for disorders in the extrinsic pathway of coagulation and for monitoring patients undergoing Oral Anti-Coagulant (OAC) therapy. Phosphoplastin RL should only be used in an appropriate clinical laboratory by qualified laboratory personnel and is provided ready-to-use.
Phosphoplastin RL PT reagent is a liquid, ready-to-use reagent containing thromboplastin derived from rabbit brain, calcium ions, buffers, stabilizers and preservatives. Phosphoplastin RL is intended for use in a one-stage prothrombin time (PT) test on citrated human plasma.
Here's an analysis of the provided text, focusing on the acceptance criteria and study information for the R2 Diagnostics Phosphoplastin RL device:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for the Phosphoplastin RL device are not explicitly stated in a dedicated section with specific numerical thresholds. Instead, the document compares its performance to a predicate device (Phosphoplastin R) to demonstrate substantial equivalence. The implied acceptance criteria revolve around achieving similar performance characteristics.
| Performance Metric | Acceptance Criteria (Implied by Predicate) | Reported Device Performance (Phosphoplastin RL) |
|---|---|---|
| Correlation with Predicate (INR data) | High correlation (e.g., r² approaching 1) and reasonable slope to the predicate device. | Site 1 (Photo-optical): r² = 0.986, slope = 0.882 |
| Site 2 (Mechanical): r² = 0.915, slope = 1.162 | ||
| Within-run Precision (CV) | CVs less than 3% (based on predicate device's reported performance in manufacturer's insert). | CVs less than 3% |
| Between-run Precision (CV) | CVs less than 3% (based on predicate device's reported performance in manufacturer's insert). | CVs less than 3% |
| Sensitivity | Ability to detect deficiencies in factors II, V, VII, and X (PT and PT-based factor assays) and sensitivity to oral anticoagulants. | Formulated to detect deficiencies in factors II, V, VII, and X (PT and PT-based factor assays). Sensitive to oral anticoagulants. (Stated as similar to predicate) |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: The document states that "normal and abnormal patient plasma, as well as plasma samples from patients undergoing oral anticoagulant therapy, were tested." However, the specific number of samples for the test set is not provided.
- Data Provenance: The correlation studies were conducted at "two sites." The information does not specify the country of origin, but given the applicant's address (South Bend, IN, USA) and the FDA submission, it's highly likely the studies were conducted in the USA. The studies appear to be retrospective in nature, using existing plasma samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
There is no mention of experts being used to establish a ground truth for the test set. The study compares the performance of the new device against an existing, legally marketed predicate device (Phosphoplastin R), which itself would have established its own reference values during its development. For in-vitro diagnostics like this, the "ground truth" is typically the result obtained from the predicate device or a recognized reference method.
4. Adjudication Method for the Test Set
There is no mention of an adjudication method. As noted above, the study is a comparison against a predicate device, rather than an assessment needing expert interpretation of novel data to establish ground truth.
5. If a Multi-reader Multi-case (MRMC) Comparative Effectiveness Study Was Done
No, a Multi-reader Multi-case (MRMC) comparative effectiveness study was not done. This type of study is more common for imaging or diagnostic devices where human readers interpret results, and the AI's role is to assist or replace that interpretation. This device is an in-vitro diagnostic reagent, where the output is typically a numerical value (PT/INR), rather than an image or complex data requiring reader interpretation.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done
This is an in-vitro diagnostic reagent, not an algorithm in the typical sense of AI/ML. The "device" itself is the reagent. The performance described is inherently "standalone" in that it's the reagent's performance in generating a PT/INR value when exposed to plasma, independent of human interpretive intervention after the test is run. However, the test is performed in a clinical laboratory by “qualified laboratory personnel,” meaning it's always used with human involvement in its application and result interpretation within a broader clinical context.
7. The Type of Ground Truth Used
The "ground truth" here is the results obtained from the legally marketed predicate device, Phosphoplastin R. The new device's performance is validated by its ability to produce results that are highly correlated and similar to those produced by the predicate device on the same plasma samples.
8. The Sample Size for the Training Set
There is no mention of a training set sample size. This type of device is a chemical reagent, not an AI/ML algorithm that requires a training set. Its formulation is based on biochemical principles, not data-driven learning.
9. How the Ground Truth for the Training Set Was Established
As there is no training set for this type of device, this question is not applicable.
§ 864.7750 Prothrombin time test.
(a)
Identification. A prothrombin time test is a device used as a general screening procedure for the detection of possible clotting factor deficiencies in the extrinsic coagulation pathway, which involves the reaction between coagulation factors III and VII, and to monitor patients receiving coumarin therapy (the administration of one of the coumarin anticoagulants in the treatment of venous thrombosis or pulmonary embolism).(b)
Classification. Class II (performance standards).