(106 days)
Cholestech LDX high sensitivity C-Reactive Protein (hs-CRP) is an in vitro diagnostic test for the quantitative determination of CRP in whole blood or serum. Measurement of CRP is useful as an aid in the detection and evaluation of infection, tissue injury, inflammatory disorders and associated diseases.
The Cholestech LDX System combines immunoassay and solid-phase technology to measure CRP. Samples used for testing can be whole blood from a fingerstick (collected in a lithium heparin coated capillary tube), venous whole blood or serum. The sample is applied to a Cholestech LDX hs-CRP cassette. The cassette is then placed into the Cholestech LDX Analyzer where a unique system on the cassette separates the plasma from the blood cells. The resultant color in the reaction is measured by reflectance photometry. A brown magnetic stripe on each cassette contains the calibration information required for the Cholestech LDX Analyzer to convert the reflectance reading to the CRP concentration in mg/L.
Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific Metric | Acceptance Criteria | Reported Device Performance (Cholestech LDX hs-CRP) |
|---|---|---|---|
| Accuracy (vs. Predicate) | Slope (Serum) | Not explicitly stated, implied to be close to 1 | 1.01 |
| Y-intercept (Serum) | Not explicitly stated, implied to be close to 0 | 0.22 | |
| "r" (Serum) | Not explicitly stated, implied to be close to 1 | 0.975 | |
| Slope (Whole Blood) | Not explicitly stated, implied to be close to 1 | 1.06 | |
| Y-intercept (Whole Blood) | Not explicitly stated, implied to be close to 0 | 0.07 | |
| "r" (Whole Blood) | Not explicitly stated, implied to be close to 1 | 0.976 | |
| Slope (Fingersticks) | Not explicitly stated, implied to be close to 1 | 1.08 | |
| Y-intercept (Fingersticks) | Not explicitly stated, implied to be close to 0 | -0.02 | |
| "r" (Fingersticks) | Not explicitly stated, implied to be close to 1 | 0.981 | |
| Assay Range | Range | 0.2 to 10 mg/L | 0.2 to 10 mg/L |
| Hematocrit Tolerance | Tolerance | N/A (implied to be within acceptable limits) | 30-55% |
| Interference | Interference % | Less than 10% | Less than 10% interference |
| Precision | %CV (Low Control) | N/A (implied clinical acceptability) | 14.3% |
| %CV (High Control) | N/A (implied clinical acceptability) | 11.5% | |
| %CV (Serum Sample @ 6.5 mg/L) | N/A (implied clinical acceptability) | 11.4% |
Note on Acceptance Criteria: The document does not explicitly state numerical acceptance criteria for slope, y-intercept, and "r" values. However, for a device claiming substantial equivalence to a predicate, the expectation is that these metrics demonstrate a strong correlation and agreement with the predicate. The reported values of r (correlation coefficient) being close to 1 (0.975, 0.976, 0.981) and slopes being close to 1 (1.01, 1.06, 1.08) with small y-intercepts (-0.02, 0.07, 0.22) indicate good agreement and likely meet the implicit acceptance criteria for substantial equivalence. The assay range and interference criteria are explicitly stated and met. Precision values are reported but no explicit acceptance thresholds are provided.
2. Sample Size and Data Provenance
- Test Set Sample Sizes:
- Accuracy (Serum vs. Predicate): 70 matched serum samples
- Accuracy (Whole Blood vs. Predicate): 76 whole blood samples (both venous and fingerstick)
- Precision: 2 levels of controls (Low and High) and one serum sample (6.5 mg/L). Each control was tested in duplicate, twice a day, over 20 days (total 80 replicates per level).
- Hematocrit Tolerance & Interference: No specific sample sizes provided, but tested with "evaluated levels" of endogenous substances.
- Data Provenance: Not explicitly stated, but clinical studies for such devices typically involve samples from a geographically diverse patient population. The document does not specify country of origin or whether the data was retrospective or prospective. Given the nature of a 510(k) submission for an in vitro diagnostic, it is generally assumed to be prospective clinical study data collected for the purpose of demonstrating device performance.
3. Number of Experts and Qualifications for Ground Truth (Test Set)
- Number of Experts: Not applicable. This study does not involve expert readers assessing images or clinical cases to establish ground truth.
- Qualifications of Experts: Not applicable.
4. Adjudication Method (Test Set)
- Adjudication Method: Not applicable. This study does not involve expert adjudication as it is a quantitative diagnostic test compared to a predicate device. The "ground truth" is established by the predicate device's measurement.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- Was it done? No. This is not an imaging AI device that relies on human interpretation. It's an in vitro diagnostic test that provides a quantitative measurement.
6. Standalone (Algorithm Only) Performance Study
- Was it done? Yes. The entire accuracy study comparing the Cholestech LDX hs-CRP device to the Dade Behring N high sensitivity CRP test is a standalone performance study. The device's output (CRP concentration) is directly compared to the predicate's output. There is no human-in-the-loop component in the measurement itself.
7. Type of Ground Truth Used
- Ground Truth Type: Predicate device measurement. The Dade Behring N High Sensitivity CRP test on the BN100 (K991385) is used as the reference standard to establish the "ground truth" for the accuracy study. This is a common approach for demonstrating substantial equivalence for new in vitro diagnostic devices.
8. Sample Size for the Training Set
- Training Set Sample Size: Not applicable. This device is an in vitro diagnostic immunoassay, not a machine learning or AI algorithm that requires a "training set" in the conventional sense. The device's performance is determined by its inherent chemical and optical properties, and its "calibration information" is encoded on the magnetic stripe of each cassette, not learned from a dataset.
9. How the Ground Truth for the Training Set Was Established
- Ground Truth Establishment (Training Set): Not applicable, as there is no "training set" in the context of this device. The device's calibration is factory-set and encoded on each cassette.
§ 866.5270 C-reactive protein immunological test system.
(a)
Identification. A C-reactive protein immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the C-reactive protein in serum and other body fluids. Measurement of C-reactive protein aids in evaluation of the amount of injury to body tissues.(b)
Classification. Class II (performance standards).