(106 days)
BD FACSCount CD4 reagents are used to enumerate the absolute counts of CD4 T lymphocytes and determine the percentage of lymphocytes that are CD4 T lymphocytes in unlysed whole blood (CD4 count and CD4 percentage). The reagents are for in vitro diagnostic use on a BD FACSCount instrument.
BD FACSCount CD4 reagents are intended for use in enumerating the absolute counts of CD4 T lymphocytes and the percentage of lymphocytes that are CD4 T lymphocytes in unlysed whole blood using the BD FACSCount instrument system. The product offers a single test that requires one convenient, ready-to-use reagent tube labeled CD4. It is intended for use on a BD FACSCount instrument. The reagent kit consists of the following components: 50 reagent tubes of CD4 PE/CD14 PE-Cy5/CD15 PE-Cy5/fluorescent nuclear dye and counting reference beads, 65 reagent tube caps, One 5-mL vial of 5% formaldehyde in phosphate-buffered saline (PBS), used as fixative solution.
Here's a breakdown of the acceptance criteria and the study results for the BD FACSCount™ CD4 Reagents, based on the provided 510(k) summary:
This device is a reagent kit for an automated differential cell counter, not an AI/ML powered device. Therefore, several of the requested categories related to AI/ML or expert adjudication in medical imaging are not applicable and will be marked as such.
Acceptance Criteria and Device Performance for BD FACSCount™ CD4 Reagents
1. Table of Acceptance Criteria and Reported Device Performance
The provided document does not explicitly state pre-defined "acceptance criteria" with numerical targets for metrics like R-squared, slope, intercept, or CV. Instead, it presents the results of equivalency studies (method comparison, precision, linearity, stability) to demonstrate that the new device performs comparably to the predicate device and within expected performance ranges for such assays.
Here's how we can infer "met acceptance criteria" based on the reported results, assuming the FDA reviewed these results and granted substantial equivalence:
| Performance Metric | Acceptance Criteria (Inferred from granted clearance) | Reported Device Performance | Device Meets Criteria? |
|---|---|---|---|
| Method Comparison: | |||
| CD4 Absolute Count (R²) | Demonstrated strong correlation (R² close to 1) with the predicate device. | 0.981 | Yes |
| CD4 Absolute Count (Slope) | Demonstrated good agreement (slope close to 1) with the predicate device. | 0.971 | Yes |
| CD4 Absolute Count (Intercept) | Demonstrated minimal bias (intercept close to 0) compared to the predicate device. | 12.695 | Yes |
| CD4 Percentage (R²) | Demonstrated strong correlation (R² close to 1) with the predicate device. | 0.99 | Yes |
| CD4 Percentage (Slope) | Demonstrated good agreement (slope close to 1) with the predicate device. | 0.999 | Yes |
| CD4 Percentage (Intercept) | Demonstrated minimal bias (intercept close to 0) compared to the predicate device. | -0.391 | Yes |
| Precision: | |||
| CD4 Abs Count (Low Control CV) (Within Device/Run) | Acceptable within-device and within-run variability for low control. (Typically below 5-10% for flow cytometry) | Within Device: 4.82% | |
| Within Run: 4.04% | Yes | ||
| CD4 Abs Count (Normal Control CV) (Within Device/Run) | Acceptable within-device and within-run variability for normal control. (Typically below 5-10% for flow cytometry) | Within Device: 4.28% | |
| Within Run: 3.46% | Yes | ||
| CD4 Percentage (Low Control CV) (Within Device/Run) | Acceptable within-device and within-run variability for low control. | Within Device: 0.38% | |
| Within Run: 0.35% | Yes | ||
| CD4 Percentage (Normal Control CV) (Within Device/Run) | Acceptable within-device and within-run variability for normal control. | Within Device: 1.28% | |
| Within Run: 1.15% | Yes | ||
| Linearity | Demonstrated linearity across the specified reportable range. | Assessed and observed to be linear within 50 - 5000 cells/ulCD4+ absolute count range. | Yes |
| Stain Stability | Demonstrated stability for stained samples up to a certain time. | Stable up to 48 hours of age of stain. | Yes |
| Reagent Stability | Demonstrated shelf-life stability for the reagents. | Stable up to 15 months. | Yes |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- Method Comparison:
- CD4 Absolute Count: n = 101 samples
- CD4 Percentage: n = 99 samples
- Precision: Not explicitly stated as a number of individual patient samples, but rather as results from "low control" and "normal control" measurements across multiple runs/devices.
- Linearity, Stain Stability, Reagent Stability: Specific sample sizes (e.g., number of replicates or distinct samples used for dilution series) are not provided.
- Method Comparison:
- Data Provenance: Not explicitly stated in the summary document. It's common for such studies to be conducted internally by the manufacturer or through clinical sites, but specific country of origin or whether it was retrospective/prospective is not detailed here. Given the nature of a 510(k) submission, it's generally assumed to be prospective data collection, but this is not confirmed.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Not applicable (N/A) for this type of device. This device is an in vitro diagnostic reagent kit for automated cell counting. The "ground truth" for comparison is typically established by the predicate device and/or reference methods, not by human experts adjudicating images or clinical findings.
4. Adjudication Method for the Test Set
- Not applicable (N/A). As explained above, for laboratory assays, "adjudication" in the sense of multiple experts reviewing and reaching consensus on findings is not a typical methodology. Performance is assessed against a predicate device or established reference methods.
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
- No, an MRMC comparative effectiveness study was not done. This device is an in vitro diagnostic reagent kit designed for automated analysis, not an AI system assisting human readers. Therefore, the concept of human readers improving with or without AI assistance is not relevant here.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Yes, in spirit, a standalone performance was done for the device system. The BD FACSCount™ CD4 Reagents are used with the BD FACSCount instrument, which performs automated analysis. The "algorithm" in this context is the instrument's automated processing and counting of labeled cells. The performance data presented (method comparison, precision, linearity, etc.) reflects the standalone performance of this integrated system (reagents + instrument) in enumerating CD4 cells. There is no human "in-the-loop" decision-making for the actual cell counting process with this automated system.
7. The Type of Ground Truth Used
- Comparison to a Predicate Device: The primary "ground truth" or reference for demonstrating substantial equivalence was the performance of the BD Tritest CD3/CD4/CD45 with and without BD Trucount absolute count tubes on a BD FACSCalibur instrument (the predicate device).
- Reference Intervals/Expected Performance: For precision and linearity, the "ground truth" is implied by expected biological ranges, established control values, and the design of dilution series to assess assay performance across its claimed dynamic range.
8. The Sample Size for the Training Set
- Not applicable (N/A) in the context of AI/ML training. This device is a reagent kit for a traditional analytical instrument. There is no "training set" in the sense of data used to train an AI/ML algorithm. The "training" of the system (instrument and reagents) would involve internal development and optimization processes by the manufacturer, but not in the AI/ML paradigm.
9. How the Ground Truth for the Training Set Was Established
- Not applicable (N/A). As there is no AI/ML training set, the establishment of ground truth for such a set is irrelevant. The "ground truth" reference for the general development and calibration of such assays would derive from established laboratory techniques, reference materials, and predicate device performance during the product development lifecycle.
§ 864.5220 Automated differential cell counter.
(a)
Identification. An automated differential cell counter is a device used to identify one or more of the formed elements of the blood. The device may also have the capability to flag, count, or classify immature or abnormal hematopoietic cells of the blood, bone marrow, or other body fluids. These devices may combine an electronic particle counting method, optical method, or a flow cytometric method utilizing monoclonal CD (cluster designation) markers. The device includes accessory CD markers.(b)
Classification. Class II (special controls). The special control for this device is the FDA document entitled “Class II Special Controls Guidance Document: Premarket Notifications for Automated Differential Cell Counters for Immature or Abnormal Blood Cells; Final Guidance for Industry and FDA.”