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CDS LTX-Control Latex Particle Suspension is intended to serve as a calibration standard for the d.c. impedance, r.f. impedance and optical light scatter parameters of the VCS module of Coulter® Models STKS, MAXM and Gen.S Hematology Analyzer systems. Models STKS and MAXM analyzers equipped with 5-part differential capability only require aspiration of the CDS LTX-Control Latex Particle Suspension through the secondary mode aspiration inlet with the analyzer set to function F5S. STKS and Gen. S analyzers equipped with 5-part differential and reticulocyte capability require aspiration of the CDS LTX-Control Latex Particle Suspension through the secondary mode aspiration inlet with the analyzer set to function F57.

The CDS LTX-Control for red cell, white cell, and platelet counting is a device that resembles red cells, white cells, and platelets, and is used to validate the electronic calibration of the volume, conductivity and light scatter parameters on Coulter® MAXM®, STKS® and GEN.S® instruments intended to count red cells, whire cells, and platelets. It is a suspension of uniform particles whose shape, size, and concentration and other characteristics have been precisely and accurately determined.

CDS LTX-Control is supplied as ready-to-use latex particles in a buffered suspension fluid. The particles pass through the flow cell producing characteristic electrical signals that are measured as volume, conductivity and light scatter for quality monitoring of the previously mentioned COULTER instruments.

Matrix base - aqueous, buffered, bacteriostatic and fungistatic medium containing a surfactant.

Constituents - alkali metal salts, detergents, antimicrobial materials and polymer beads of known size.

The document describes the CDS LTX-Control, a latex particle suspension used as a calibrator for hematology analyzers (Coulter MAXM, STKS, and GEN.S). It aims to validate the electronic calibration of volume, conductivity, and light scatter parameters.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance:

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

• Test Set Sample Size: For stability testing and value assignment, 31 cycles are performed repeatedly for the LTX-Control. The first cycle is discarded, and the mean is calculated from the remaining 30 replicates.
  • For the NIST-traceable primary particle standard, it is assayed 11 times, with the first value discarded, and the remaining 10 values used to calculate a mean.
  • For validation of the analyzer system with commercial controls, at least three levels of commercial control materials are assayed for three cycles each.
  • For comparison with normal human blood, "normal human blood specimens" are used, but a specific number / sample size is not stated beyond "mean average of the normal sample results."
  • Data tables (Tables I and II) are presented for two lot numbers of CDS LTX-Control.
  • Table 100 shows the analysis of the NIST-traceable primary particle standard.
• Data Provenance: The document does not explicitly state the country of origin of the data. Given the address of the manufacturer (Clinical Diagnostic Solutions, Inc. in Plantation, FL, USA) and the FDA 510(k) submission, it is highly likely the data was generated in the United States. The stability studies refer to "pilot production material." The studies appear to be prospective as they involve specific testing protocols for stability, value assignment, and comparison studies.

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

• The document does not explicitly mention the use of human experts or radiologists to establish ground truth for the test set.
• The ground truth for the CDS LTX-Control is established through comparison with:
  • Previous values from the same lot (for stability).
  • Reference values assigned by the manufacturer for commercial control materials.
  • A NIST-traceable primary particle standard.
  • Mean averages derived from normal human blood specimens.
  • This implies an objective, quantitative ground truth based on established measurement standards and existing commercial controls, rather than subjective expert consensus.

4. Adjudication Method for the Test Set:

• No human adjudication method (e.g., 2+1, 3+1) is described.
• The determination of acceptance is based on pre-defined quantitative criteria (e.g., ±3% deviation, ±10% deviation) and statistical calculations (mean, standard deviation, coefficient of variation, t-test). If an instrument malfunction affects results, recalibration to known standards is used to correct values.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:

• No, an MRMC comparative effectiveness study was not done. This device is a calibrator for automated hematology analyzers, not an AI diagnostic tool used by human readers. Therefore, the concept of human readers improving with or without AI assistance is not applicable.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study:

• Yes, the studies described are essentially standalone performance evaluations of the CDS LTX-Control itself and its ability to calibrate the specified automated hematology analyzers. The device is a physical standard, and its performance (e.g., consistency, accuracy relative to other standards) is assessed directly through repetitive measurements on the target analyzers. There is no "human-in-the-loop" directly interacting with the calibrator's output in a diagnostic capacity; rather, the calibrator ensures the instrument's algorithm/measurement system is working correctly.

7. Type of Ground Truth Used:

• The ground truth used is primarily objective, quantitative, and traceable to established standards:
  • Manufacturer-assigned reference values for commercial control materials.
  • NIST-traceable primary particle standards (for transferring known particle sizes).
  • Statistical averages/means derived from a large number of replicates and normal human blood specimens, serving as a baseline for expected performance.
  • Instrument calibration standards.

8. Sample Size for the Training Set:

• The document describes a calibration and quality control product, not a machine learning algorithm. Therefore, the concept of a "training set" in the context of AI/ML is not applicable. The device itself is a "standard" or "control" that is used to calibrate or train other instruments, rather than being "trained" itself.

9. How the Ground Truth for the Training Set Was Established:

• As the concept of a "training set" in the AI/ML sense is not applicable, the ground truth for an AI training set was not established.
• Instead, the "ground truth" for the CDS LTX-Control's assigned values is established through rigorous comparative studies as outlined in point 7, involving traceability to NIST standards, comparisons with commercial controls, and assessment against normal human blood values on properly calibrated instruments.

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