(92 days)
PF4 Enhanced assay is designed as a solid phase enzyme linked immunosorbent assay (ELISA). The product is intended to be used as an in vitro diagnostic kit by hematology, coagulation, or other pathology laboratories to assist in screening patient samples, 3.2% sodium citrate (plasma) or without anticoagulant (serum), for the presence of heparin associated commonly found in patients with heparin induced thrombocytopenia (HIT) or thrombosis.
PF4 Enhanced Assay is an Enzyme Linked Immunosorbent Assay (ELISA). The PF4 Enhanced ELISA is intended to detect antibodies in human serum or plasma that react with Platelet Factor 4 (PF4) when it is complexed to heparin or other polyanionic compounds. The PF4 Enhanced kit contains all of the reagents necessary to perform the assay.
Here's a breakdown of the acceptance criteria and supporting studies for the Immucor PF4 Enhanced assay, based on the provided FDA 510(k) summary:
1. Table of Acceptance Criteria and Reported Device Performance
| Feature/Metric | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Positive Serum Control | Average OD value ≥ 1.800 OD for each vial tested. Duplicate test well OD values ≤ 20% of the mean of the two values. | All acceptance criteria were met for three validation batches, consistently delivering product meeting established acceptance criteria. |
| Comparison of Serum & Plasma | Acceptable percent agreement between qualitative results using serum or plasma. Positive agreement in OD values with a slope > 0.9 (up to 4.0 OD). | 94.8% agreement (164/173) observed initially, increasing to 95.4% (164/172) after investigating and removing one incorrect fresh serum result. Comparison of OD values showed positive agreement with a slope > 0.9. |
| Stopping Solution Lot-to-Lot | New Stopping Solution (ESS) performs equivalently to the predicate Stopping Solution (3M NaOH). | All acceptance criteria were met, demonstrating the new ESS is acceptable. |
| Stopping Solution Process Validation | All well-to-well variations meet acceptance criteria. All finished product QC panel samples (21 positive, 24 negative) yield expected qualitative results with the new ESS. All assays meet IFU QC requirements. | All wells met acceptance criteria for well-to-well variation. All 21 positive and 24 negative samples met their expected qualitative result across three lots of new ESS and one lot of 3M NaOH. All assays met the QC requirements in the IFU. |
| Shelf Life | Stability data supports a 24-month shelf life. | All acceptance criteria for stability studies were met, supporting a 24-month shelf life. |
2. Sample Sizes Used for the Test Set and Data Provenance
- Positive Serum Control Raw Material Change: 30 vials tested (total number of samples from 3 validation batches is not explicitly stated beyond this).
- Comparison of Serum and Plasma Sample Types: 174 paired (serum vs. plasma) fresh samples.
- Data Provenance for Serum/Plasma Comparison: Florida Hospital conducted the study. The data was retrospective as Genetic Testing Institute (the prior company) used the transcribed raw data for analysis. The country of origin is implicitly the U.S.
- Stopping Solution Lot-to-Lot Comparison: 3 lots of new Stopping Solution (ESS) and 3M NaOH (predicate). Number of actual test samples per lot not specified beyond implied sufficient testing to meet acceptance criteria.
- Stopping Solution Process Validation: 3 lots of new Stopping Solution (ESS) and 1 lot of 3M NaOH (predicate). Tested with a finished product QC panel of 21 positive and 24 negative samples (total 45 samples per lot/solution type).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not explicitly state the number of experts or their qualifications for establishing ground truth. For the Comparison of Serum and Plasma Sample Types, it mentions "Florida Hospital conducted a study" and "Genetic Testing Institute used the transcribed raw data to perform the analysis." This suggests clinical outcomes or internal lab testing might have served as ground truth, rather than expert consensus on individual cases. For other studies, "established acceptance criteria" and "expected qualitative result" imply pre-defined truths based on known characteristics of control materials or validated samples.
4. Adjudication Method for the Test Set
The document does not mention an explicit adjudication method (e.g., 2+1, 3+1). For the Comparison of Serum and Plasma Sample Types, it notes an "investigation of the ninth discrepant sample," where "additional testing for the plasma and serum sample both matched that of the fresh plasma sample," suggesting a form of re-evaluation or retesting for discrepant results.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, an MRMC comparative effectiveness study was not done. The device is an in vitro diagnostic (ELISA) kit.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, the studies presented are all standalone performance evaluations of the assay components and the assay as a whole, without human-in-the-loop performance being a specific metric. The device itself is an assay kit.
7. The Type of Ground Truth Used
- Positive Serum Control Raw Material Change: Ground truth was based on pre-defined expected optical density (OD) values and variation limits for the control material.
- Comparison of Serum and Plasma Sample Types: Ground truth for sample positivity/negativity would have been established by the clinical laboratory (Florida Hospital) using the predicate device or a clinical diagnosis, which the new method was compared against. It's implied this was based on the "qualitative results obtained."
- Stopping Solution Lot-to-Lot Comparison: Ground truth was based on the performance of the predicate Stopping Solution (3M NaOH) and established qualitative results for known samples.
- Stopping Solution Process Validation: Ground truth was based on the expected positive/negative qualitative results of a "finished product QC panel" and the performance of the predicate 3M NaOH Stopping Solution.
8. The Sample Size for the Training Set
The document does not specify a training set for algorithm development, as the device is an ELISA kit and not an AI/ML algorithm that typically requires a separate training set. The studies described are validation and performance testing of the kit's components and overall function.
9. How the Ground Truth for the Training Set was Established
Not applicable, as there is no mention of an algorithm training set.
§ 864.7695 Platelet factor 4 radioimmunoassay.
(a)
Identification. A platelet factor 4 radioimmunoassay is a device used to measure the level of platelet factor 4, a protein released during platelet activation by radioimmunoassay. This device measures platelet activiation, which may indicate a coagulation disorder, such as myocardial infarction or coronary artery disease.(b)
Classification. Class II (performance standards).