(458 days)
Ortho-mune OK-COMBO CD4-FITC/CD8-PE is intended for use in identification and enumeration of CD4+ and CD8+ human T lymphocytes in whole blood by flow cvtometry. The intended use is the same as the intended use of the predicate device. Simultest CD4/CD8 (Leu-3a/2a) commercially distributed by Becton Dickinson Immunocytometry Systems.
Ortho-mune OK-COMBO CD4-FITC/CD8-PE (OKT4A/OKT8) Monoclonal Antibody (Murine) is a blend of the individual purified monoclonal antibodies OKT4A and OKT8 conjugated to the fluorochromes fluorescein isothiocyanate and phycoerythrin respectively.
1. Table of Acceptance Criteria and Reported Device Performance
| Test Type | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Equivalence | Demonstrate equivalence to the predicate device (Simultest CD4/CD8) in identification and enumeration of CD4+ and CD8+ human T lymphocytes in whole blood. | Regression Analysis: |
- CD4+: Y = 1.886 + 1.08500 (Ortho-mune) vs. Predicate. Correlation coefficient R = 0.971.
- CD8+: Y = 0.112 + 0.84400 (Ortho-mune) vs. Predicate. Correlation coefficient R = 0.955.
Mean % Positive Stained Cells (Normal Donors, N=190):
- CD4+: Ortho-mune: 47.5% (Range: 11.6-70.8); Predicate: 44.1% (Range: 13.1-61.2)
- CD8+: Ortho-mune: 27.8% (Range: 10.9-72.8); Predicate: 29.5% (Range: 12.5-69.1)
Mean % Positive Stained Cells (AIDS/ARC Patients, N=83):
- CD4+: Ortho-mune: 18.2% (Range: 0.1-60.4); Predicate: 15.8% (Range: 0.2-50.4)
- CD8+: Ortho-mune: 56.1% (Range: 12.6-81.9); Predicate: 58.9% (Range: 22.5-88.4)
Conclusion: Performance shown to be equivalent to the predicate device. |
| Reproducibility| Acceptable within and between laboratory reproducibility for determining total CD4+ and CD8+ lymphocyte percentages. | Within Laboratory Reproducibility (N=11 donors, 3 sites):
- CD4+ Low (mean 11.232%): CVs from 6.701% to 8.268%
- CD4+ Normal (mean 49.455%): CVs from 2.443% to 3.118%
- CD4+ High (mean 67.528%): CVs from 2.093% to 3.360%
- CD8+ Low (mean 7.521%): CVs from 7.186% to 15.735%
- CD8+ Normal (mean 32.782%): CVs from 3.102% to 4.244%
- CD8+ High (mean 56.234%): CVs from 2.462% to 3.392%
Between Laboratory Reproducibility (N=11 donors, 3 sites):
- CD4+ Low: CV 5.496%
- CD4+ Normal: CV 1.189%
- CD4+ High: CV 1.729%
- CD8+ Low: CV 5.453%
- CD8+ Normal: CV 0.427%
- CD8+ High: CV 1.354%
Conclusion: Acceptable within and between laboratory reproducibility demonstrated. |
| Linearity | Demonstrate linear performance for both total CD4+ and CD8+ lymphocyte subsets across a range of lymphocyte counts. | Linear performance demonstrated for both total CD4+ and CD8+ lymphocyte subsets across a lymphocyte count range of 20 cells/ul to 18,676 cells/ul. Slopes were indistinguishable from 1 and R values were 1.000. |
2. Sample Sizes Used for the Test Set and Data Provenance
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Test Set for Equivalence (Comparison with Predicate Device):
- Sample Size: 190 normal donors and 83 AIDS/ARC patients (total 273 specimens).
- Data Provenance: The study was conducted at "three external, geographically distinct sites." The countries of origin are not specified, but the use of "normal donors" and "AIDS/ARC patients" suggests clinical samples. The data is prospective, collected specifically for this study.
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Test Set for Reproducibility:
- Sample Size: 11 normal donors. Samples from these donors were processed to create low, normal, and high relative percent CD4+ and CD8+ cells. Each sample was stained in replicates of 10.
- Data Provenance: Not explicitly stated, but samples were processed and analyzed at "three independent laboratories." This implies the samples were real human whole blood specimens. The data is prospective.
-
Test Set for Linearity:
- Sample Size: 4 normal donors. Specimens were processed to produce samples with low, normal, and high numbers of lymphocyte subsets. Each sample was stained in triplicate.
- Data Provenance: Not explicitly stated, but implies real human whole blood specimens. The data is prospective.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
Not applicable. This device is an in vitro diagnostic reagent for flow cytometry, which measures cell populations. The "ground truth" for this type of device is the measurement obtained from the predicate device and the internal consistency/characteristics (reproducibility, linearity) of the new device itself. There are no human expert adjudicators for establishing a "ground truth" in the way one would for diagnostic imaging. The comparison is against an established method and assessed by statistical measures.
4. Adjudication Method for the Test Set
Not applicable. As described above, this is a quantitative measurement device, not an imaging or qualitative diagnostic device requiring expert adjudication. The comparison with the predicate device was based on statistical regression analysis and direct comparison of mean percentages and ranges.
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
Not applicable. This is not an AI/imaging device that involves human readers or interpretation of complex cases. It is an in vitro diagnostic reagent that identifies and enumerates specific cell populations using flow cytometry.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done
Yes, in a sense. The "device" (reagent) is evaluated in a standalone manner by comparing its output (percentage of positive stained cells) directly against that of a predicate device and by assessing its intrinsic performance characteristics (reproducibility, linearity). The analysis is performed by a flow cytometer, and the interpretation of the results from the flow cytometer (i.e., the percentages) is then compared between the new reagent and the predicate reagent. There is no "human-in-the-loop performance" that would alter the quantitative output of the reagent and cytometer system itself.
7. The Type of Ground Truth Used
- For Equivalence Study: The "ground truth" was established by the predicate device's measurements (Simultest CD4/CD8). The study aimed to show that the new device's measurements were statistically equivalent to the predicate device's measurements.
- For Reproducibility and Linearity Studies: The "ground truth" was established based on internal consistency and expected biological behavior. For reproducibility, the ground truth is that repeated measurements of the same sample should yield similar results (low variance). For linearity, the ground truth is that the measured cell counts should scale proportionally with dilution.
8. The Sample Size for the Training Set
Not applicable. This device is a monoclonal antibody reagent used in flow cytometry, not a machine learning or AI model. Therefore, there is no "training set" in the context of algorithm development. Its performance is based on the inherent specificity and binding characteristics of the antibodies.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no training set for this type of device.
§ 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.”