(103 days)
Cell-Chex is an assayed control intended for monitoring total cell counts performed manually using a hemocytometer to validate quantitation of red and white blood cells in patient cerebrospinal fluid and body fluid samples including pleural, pericardial, peritoneal and synovial fluid. Level 1 contains monosodium urate crystals which can be used to monitor the presence of crystals in synovial fluid.
Cell-Chex is also intended for monitoring white blood cell differentiation (Mononuclear, Polymorphonuclear: Neutrophils, Eosinophils, Basophils, Lymphocytes and Monocytes) in body fluid samples performed using Cytospin® smears.
Cell-Chex is a stabilized suspension of human red blood cells, human white blood cells and monosodium urate crystals (Level 1 only) in a preservative medium. The product is packaged in glass vials containing 2.0ml. The closures are polypropylene screw caps with polyethylene liners. There are two different levels. Level 1 contains a low cell count and monosodium urate crystals, and Level 2 contains a high cell count and no crystals. The vials will be packaged in a six (6) or twelve (12) welled vacuum formed "clam-shell" container with the package insert / assay sheet. The product must be stored at 2 - 10° C.
The provided text describes the 510(k) submission for "Cell-Chex," a hematology control for body fluids. The device is intended for monitoring total cell counts and white blood cell differentiation using manual methods (hemocytometer and Cytospin® smears). The key change from the predicate device is the addition of monosodium urate crystals in Level 1 for monitoring crystal presence in synovial fluid.
Here's an analysis based on the provided text, addressing your specific questions:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state numerical acceptance criteria for various performance metrics. Instead, it describes the types of studies conducted and their general conclusions. The "reported device performance" is qualitative, indicating the device meets its intended use and is comparable to the predicate.
| Acceptance Criterion (Implicit from Study Types) | Reported Device Performance |
|---|---|
| Closed Vial Stability | Cell-Chex is stable for the shelf life claimed (60 days). |
| Open Vial Stability | Cell-Chex is stable for the open vial stability claimed (30 days). |
| Run-to-Run Reproducibility | Cell-Chex is consistently reproducible. |
| Precision Performance Data | Cell-Chex performs comparably to the predicate product. |
| Crystal Detection (Level 1 only) | Can be used to monitor the presence of crystals in synovial fluid (listed as positive or negative). |
2. Sample Size Used for the Test Set and Data Provenance
The document does not specify the sample size for the test sets used in the Closed Vial Stability, Open Vial Stability, Run-to-Run Reproducibility, or Precision Performance Data studies.
The data provenance is not explicitly stated as retrospective or prospective, nor does it mention the country of origin of the data. Given the nature of a control device, the "data" would likely originate from internal testing conducted by the manufacturer (Streck).
3. Number of Experts Used to Establish Ground Truth and Qualifications
The document does not mention the use of experts to establish ground truth for a test set in the traditional sense of clinical readings. This device is a control product, meaning its performance is evaluated against expected values for cell counts and crystal presence, not against expert interpretations of patient samples.
4. Adjudication Method for the Test Set
Since there were no human readers or expert interpretations of a test set of patient cases, an adjudication method like 2+1 or 3+1 is not applicable and therefore, not mentioned.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was mentioned or performed. This type of study is typically conducted for diagnostic devices where human interpretation directly impacts diagnosis and patient outcomes, and the AI is meant to assist human readers. Cell-Chex is a control used to validate the manual counting procedures, not a diagnostic AI system itself.
6. Standalone (Algorithm Only) Performance Study
No standalone performance study for an algorithm was done. Cell-Chex is a physical control material and does not involve an algorithm with standalone performance. Its purpose is to provide known values for manual counting methods.
7. Type of Ground Truth Used
The "ground truth" for Cell-Chex's performance is established by its known, pre-defined characteristics as a control material. This includes:
- Expected cell counts (red blood cells, white blood cells).
- Expected white blood cell differentiation percentages.
- Presence or absence of monosodium urate crystals (for Level 1).
These values are determined during the manufacturing and characterization of the control product itself, rather than by expert consensus on external patient data or pathology. The studies (stability, reproducibility, precision) then verify that the product consistently maintains these known characteristics over time and across different manufacturing lots.
8. Sample Size for the Training Set
There is no mention of a training set sample size. This device does not involve a machine learning algorithm that requires training data.
9. How Ground Truth for the Training Set was Established
As there is no training set for a machine learning algorithm, this question is not applicable. The "ground truth" for the control material's inherent properties is established through the manufacturing process and quality control measures.
§ 864.8625 Hematology quality control mixture.
(a)
Identification. A hematology quality control mixture is a device used to ascertain the accuracy and precision of manual, semiautomated, and automated determinations of cell parameters such as white cell count (WBC), red cell count (RBC), platelet count (PLT), hemoglobin, hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC).(b)
Classification. Class II (special controls). Except when intended for use in blood components, the device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 864.9.