Search Results

The EZCD4 Assay is intended to be performed on a Guava PCA System with CytoSoft 2.3 version software which includes three modules; EZCD4, Guava Check and Clean and Shutdown. The system is intended to identify and quantify the absolute counts of CD4 T-Lymphocytes in EDTA whole blood. The GuavaEZCD4 system is intended for the ongoing monitoring of patients with documented diagnosis of an immunodeficiency disease. The Guava EZCD4 system is intended for use only by trained laboratory professionals.

The Guava EZCD4 System is an optimized cell analysis system consisting of the Guava PCA instrument, EZCD4 software for data acquisition and analysis and an EZCD4 Reagent Kit consisting of optimized reagents and protocols. The Guava EZCD4 Reagent Kit is a two-color direct immunofluorescence kit used for the enumeration of mature CD4 T lymphocytes in human blood. It consists of a monoclonal anti-human CD3 antibody conjugated to the tandem dye, phycoerythrin (PE)-Cy5 (PECy5) and a monoclonal anti-human CD4 antibody conjugated to PE. Guava 1X Lysing Solution and Guava Fixative are available in separate packaging and are added, after staining, to lyse erythrocytes and to preserve cells respectively. The Guava PCA instrument includes a laptop computer. The Guava PCA incorporates a new technology termed micro capillary cytometry. The device is a 3-parameter flow cytometer that utilizes a solid state 532 nm green laser, a fixed optical & fluidic system, a self-aligning flow cell and a micro capillary delivery system to perform cell analysis. The micro-syringe stepper pump allows the use of small sample volumes and volumetric measurements for the determination of absolute counts per microliter. The Guava PCA optic system detects forward scatter and two different wavelengths of fluorescence, 580/20 nm and 675/20 nm. It has a small foot print, 21.6 cm x 32 cm x 36.3 cm and is equipped with a network ready laptop computer with a 10GB hard drive and Windows 2000 operating system. The software is application specific with onscreen messaging enabling ease of use and facilitates short, effective training programs. Data is readily analyzed immediately after acquisition and is stored as electronic files on the hard drive.

{
  "acceptance_criteria_and_performance_table": {
    "title": "Summary of Guava EZCD4 System Performance Studies",
    "headers": [
      "Study Type",
      "Acceptance Criteria",
      "Reported Device Performance"
    ],
    "rows": [
      [
        "Correlation Study (vs. Predicate Devices)",
        "Not explicitly stated as numerical acceptance criteria, but implied demonstration of substantial equivalence via linear regression (R-squared, Slope, Intercept).",
        "**Site 2:** N=92, R-squared=0.95, Slope=+1.00, Intercept=18.64, Range=13-1465\n**Site 3:** N=91, R-squared=0.93, Slope=+0.96, Intercept=35.51, Range=17-1175\n**Site 4:** N=88, R-squared=0.98, Slope=+1.17, Intercept=18.46, Range=47-1439\n**Site 5:** N=94, R-squared=0.98, Slope=+0.95, Intercept=13.29, Range=8-1076\n(Conclusion: Results are substantially equivalent)"
      ],
      [
        "Linearity and Sensitivity Study",
        "Not explicitly stated as numerical acceptance criteria, but implied demonstration of linearity across a wide range of CD4+ T cell counts.",
        "Linear regression equation: y = 1.0118x - 45.237\nR-squared = 0.9866\n(Graph shows strong linearity from 0 to >2000 CD4+ T cells/µL)"
      ],
      [
        "Intra-Laboratory Reproducibility",
        "Not explicitly stated as numerical acceptance criteria (e.g., max CV%), but implied low variability across sites and ranges.",
        "**Site 2:** Low CV=13.50%, Mid CV=8.06%, High CV=4.75%\n**Site 3:** Low CV=10.45%, Mid CV=7.20%, High CV=4.92%\n**Site 4:** Low CV=11.05%, Mid CV=3.87%, High CV=3.56%\n**Site 5:** Low CV=4.69%, Mid CV=3.69%, High CV=3.23%"
      ],
      [
        "Carryover Study",
        "Absence of significant sample carryover, as determined by statistical comparison.",
        "Wilcoxon-Mann-Whitney test 1-sided p-value = 0.1474 (Conclusion: No significant sample carryover demonstrated)"
      ],
      [
        "Specificity Study (Guava anti-CD3)",
        "Expected specificity for peripheral blood lymphocytes.",
        "Mean % positive in Lymphocytes: 47.80%\nMean % positive in Monocytes: 3.52%\nMean % positive in Granulocytes: 1.52%\n(Conclusion: Expected specificity for lymphocytes)"
      ],
      [
        "Specificity Study (Guava anti-CD4)",
        "Expected specificity for peripheral blood lymphocytes, allowing for known weak positive staining of monocytes.",
        "Mean % positive in Lymphocytes: 23.58%\nMean % positive in Monocytes: 81.58%\nMean % positive in Granulocytes: 4.39%\n(Conclusion: Expected specificity for lymphocytes, with known weak positive for monocytes)"
      ],
      [
        "Blood Sample Aging (Pre-Staining)",
        "Storage of unstained EDTA whole blood for specific periods without significant impact on results.",
        "Unstained EDTA anti-coagulated whole blood specimens may be stored for periods up to and including 72 hours (at 18-25°C) prior to staining and analysis."
      ],
      [
        "Blood Sample Aging (Post-Staining)",
        "Storage of stained and fixed EDTA whole blood for specific periods without significant impact on results.",
        "Stained EDTA anti-coagulated whole blood specimens may be stored for periods up to and including 24 hours (at 18-25°C or 2-8°C) prior to analysis."
      ]
    ]
  },
  "study_details": {
    "test_set_sample_size": {
      "correlation_study": "365 abnormal whole blood samples (approximately 90 per site) from three CD4+ absolute count ranges (0-200, 201-500, 501-2000).",
      "linearity_sensitivity": "22 aliquots (11 pairs) prepared from bulk blood samples.",
      "intra_laboratory_reproducibility": "10 replicate whole blood samples from each of three abnormal donors (low, mid, high ranges) per site, across 4 sites. Total 120 samples (3 donors x 10 replicates x 4 sites).",
      "carryover_study": "21 low range sample replicates and 18 high range sample replicates in a specific alternating sequence.",
      "specificity_study": "5 healthy subjects, EDTA anti-coagulated whole blood samples, analyzed for 15,000 events per blood component for each donor.",
      "blood_sample_aging": "Pre-Staining: 5 healthy normal donors, 5 blood specimens each (total 25 specimens). Post-Staining: 5 healthy normal donors, 7 stained samples per blood sample, pooled (total 35 samples for 18-25°C and 35 for 2-8°C)."
    },
    "data_provenance": {
      "correlation_study": "Prospective, collected at four clinical trial sites in the US.",
      "specificity_study": "Prospective, collected from healthy subjects.",
      "blood_sample_aging": "Prospective, collected from healthy normal donors."
    },
    "number_of_experts_ground_truth_test_set": "Not applicable, as these studies primarily assessed device performance against predicate devices or expected biological/analytical characteristics rather than expert-derived ground truth.",
    "qualifications_of_experts": "Not applicable.",
    "adjudication_method": "Not applicable.",
    "mrmc_comparative_effectiveness_study": "No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly described, as this is a device for quantifying CD4+ T cells, not for image interpretation by human readers. The correlation study compared the device's output to predicate flow cytometry systems.",
    "standalone_performance_done": "Yes, various standalone performance metrics were evaluated, including linearity, reproducibility (intra-laboratory precision), carryover, and specificity. The correlation study also assessed its performance against predicate devices.",
    "type_of_ground_truth_test_set": {
      "correlation_study": "Reference measurements from predicate flow cytometry systems (Becton Dickinson FACSCalibur with MultiTest or TriTest reagents).",
      "linearity_sensitivity": "Known 'Expected values' derived from gravimetric preparation of blood cell aliquots with known high and low CD4+ T cell counts.",
      "intra_laboratory_reproducibility": "The device's own measurements across replicates and sites, assessing internal consistency; no external 'ground truth' in the context of diagnostic accuracy.",
      "carryover_study": "The device's own measurements of alternating low and high concentration samples, showing lack of influence.",
      "specificity_study": "The characteristic immunological staining patterns of known cell populations (lymphocytes, monocytes, granulocytes) as observed on a reference flow cytometer (FACSCalibur) with the study reagents.",
      "blood_sample_aging": "The device's own measurements at different time points, comparing to the initial (0 hour) measurement value as a reference for stability."
    },
    "training_set_sample_size": "Not specified. As this is a flow cytometer system with reagents and software for quantitative measurements, it's unlikely to have a 'training set' in the machine learning sense. The software's algorithms would likely be based on established flow cytometry principles and calibrated/validated during development.",
    "how_ground_truth_training_set_established": "Not applicable. The system's operation and algorithms for data acquisition and analysis are based on established principles of flow cytometry and are likely calibrated and validated through internal development and testing, rather than an external 'ground truth' for a machine learning training set."
  }
}

Ask a specific question about this device

TRUCOUNT Absoluce Count Tubes are intended for use as an accessory to TriTEST in vitro diagnostics, such as that described in K965053 (CD3/CD4/CD45), to allow computation of positive cells per known volume of blood, using flow cytometty.

The TRUCOUNT Counting Control Beads are provided in three levels, and are intended to provide a means to check the reproducibility and accuracy of volumeric pipetting of blood samples. They are an accessory to TriTEST reagens, when used with TRUCOUNT Absolute Count Tubes to obtain absolute counts of positive cells using flow cytomerry.

Indications for Use:

• For erythrocyte lysed whole blood .
• For use with FACS Loader ●
• For use with IVD immunophenotyping reagents .
• For use on flow cytometers with designated detection ranges ●
• For use to obtain absolute counts by flow cytometry ◆

TRUCOUNT Absolute Count Tubes are fluorescent particles supplied as a peller in a rube. The peller contains a known number of beads. A blood sample of known volume is added to the rube. Then the appropriate reagent is added to the mixture. By comparing the number of positive cell events to the number of bead events in the flow cytomerry data ourpur, posicive cells per unit volume of blood sample can be computed.

TRUCOUNT Counting Control Beads are fluorescent particles supplied as suspensions in three bead concentrations, High, Medium and Low. The fluorescence of these beads is similar to that of the Absolute Count Tube in FL1 and FL3, but is different in FL2, so that both beads may be run in the same sample, and distinguished from one another. Control beads are added to samples of normal blood prepared with TriTEST reagents and Absolute Count Tubes. The Concrol Bead count is obtained by comparison to the count of the Absolute Count Tubes. These experimental counts are compared to the expected count on the Control Bead label, to check the accuracy of pipetting.

The provided document, K970836, is a 510(k) submission for the TRUCOUNT Absolute Count Tubes and TRUCOUNT Counting Control Beads by Becton Dickinson Immunocytometry Systems, cleared in 1997. It describes the device, its intended use, comparison to predicate devices, and performance data. However, the document does not present a typical "acceptance criteria and study that proves the device meets the acceptance criteria" in the format commonly seen for contemporary medical devices. Instead, it describes performance testing completed to support the device's claims for substantial equivalence.

Here's an analysis of the provided information within the requested framework, highlighting where information is not explicitly stated or is inferred from the context of an older 510(k) submission.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a table of "acceptance criteria" with quantitative targets. Instead, it describes performance characteristics that were assessed and found "acceptable" to support the device's claims. The reported performance is qualitative for stability and accuracy.

• TRUCOUNT Counting Control Beads: Found acceptable to support a six-month shelf life.
• Absolute Count Tubes: Remain stable after foil pouch opened if stored closed at room temperature with blue desiccant. |
  | Accuracy/Reproducibility | Support ranges for acceptable performance cited in the Package Insert. | - Counting Control Beads: Determined and found acceptable to support the ranges for acceptable performance cited in the Package Insert. |
  | Functionality (with FACS Loader) | Function as expected when used with FACS Loader and manually. | - Absolute Count Tubes and Counting Control Beads: Seen to function as expected when used with the FACS Loader, as well as manually. |

2. Sample Size Used for the Test Set and Data Provenance

The document states: "Performance of the product was established by testing at Becton Dickinson Immunocytometry Systems laboratories in San Jose, California."

• Test Set Sample Size: Not explicitly stated. The document doesn't provide numerical sample sizes for any of the performance tests (stability, accuracy, reproducibility, or functionality).
• Data Provenance:
  • Country of Origin: United States (San Jose, California).
  • Retrospective or Prospective: Not explicitly stated, but the description of "testing at Becton Dickinson Immunocytometry Systems laboratories" suggests prospective internal testing conducted for the submission.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

Not applicable. This device (TRUCOUNT Absolute Count Tubes and Counting Control Beads) is a calibration/control accessory for flow cytometry. Its performance is based on intrinsic physical and chemical properties and its ability to provide a known count of beads for volumetric measurements. Ground truth for its performance would typically be established through manufacturing controls, certified reference materials, and metrological standards, rather than expert consensus on clinical images or interpretations.

4. Adjudication Method for the Test Set

Not applicable. As noted above, the performance assessment is based on quantifiable physical properties and functional checks, not on interpretation by human experts that would require adjudication.

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, and is not applicable for this type of device. An MRMC study is typically used for diagnostic interpretation devices where human readers' performance is being evaluated, especially with and without AI assistance. This device is an accessory that assists in counting cells, not in interpreting diagnostic images or clinical data.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done

Parts of the testing could be considered "standalone" in the sense that the device's intrinsic characteristics (like bead count, fluorescence, stability) are being evaluated. However, the device's ultimate "performance" is as an accessory used with other devices (flow cytometers and reagents) and by human operators. The document mentions "functions as expected when used with the FACS Loader, as well as manually," indicating an evaluation of its performance in conjunction with other components of the workflow, rather than a purely standalone algorithm.

7. The Type of Ground Truth Used

The ground truth for the device's performance is implicitly tied to:

• Manufacturing Specifications / Certified Bead Counts: For the TRUCOUNT Absolute Count Tubes, the "known number of beads" in the tube constitutes a pre-defined ground truth established during manufacturing and rigorously controlled.
• Expected Counts (for Control Beads): For the TRUCOUNT Counting Control Beads, the "expected count on the Control Bead label" serves as the ground truth against which experimental counts are compared to check pipetting accuracy.
• Established Analytical Methods: Stability is assessed against established protocols for degradation (e.g., measuring physical or chemical changes over time).

This is an analytical ground truth based on device design and manufacturing controls, not clinical outcomes, pathology, or expert consensus on a diagnostic finding.

8. The Sample Size for the Training Set

Not applicable. This device is a consumable accessory for flow cytometry, not an AI/ML algorithm that requires a training set. The performance testing described is for product validation, not algorithm training.

9. How the Ground Truth for the Training Set was Established

Not applicable, as there is no training set for this type of device.

Ask a specific question about this device