(42 days)
The S-Test Creatine Kinase Reagent is intended for the quantitative determination of Creatine Kinase activity in serum or heparin plasma using the S40 Clinical Analyzer. Measurements of creatine phosphokinase activity are used in the diagnosis and treatment of myocardial infarction and muscle diseases such as progressive, Duchenne-type muscular dystrophy. This test is intended for use in clinical laboratories or physician office laboratories. For in vitro diagnostic use only.
The S-Test Creatine Kinase (CK) reagent cartridge, used with the S40 Clinical Analyzer, is intended for quantitative in vitro diagnostic determination of CK activity in serum or heparin plasma based on a photometric test measuring the formation of NADPH, which absorbs strongly at 340 nm.
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Precision | Consistent and low variability in results (low CV%) for different CK levels. | In-house (22 days): |
- Within-run CV: 1.4% to 2.0% (at three CK levels)
- Total CV: 5.1% to 6.1%
Field (3 POL sites, 5 days):
- Within-run CVs: 0.5% to 3.7%
- Total CVs: 0.8% to 3.7% |
| Accuracy | High correlation with a comparative method (high correlation coefficient, slope near 1, intercept near 0, low standard error). | Correlation Study (95 samples, CK: 32-1181 U/L): - Correlation coefficient (r): 0.998
- Standard error estimate: 14.5
- Confidence interval slope: 1.027 to 1.053
- Confidence interval intercept: -12.5 to -5.2
Patient Correlation Studies (3 POL sites):
- Correlation coefficients (r): 1.00
- Standard error estimates: 5.0 to 8.5
- Confidence interval slopes: 1.006 to 1.059
- Confidence interval intercepts: -10.8 to -3.5 |
| Sensitivity | Ability to detect low levels of CK activity. | The detection limit was 24 U/L. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size:
- Precision:
- In-house: Not explicitly stated, but "three CK levels for 22 days" implies a substantial number of replicates per level.
- Field: Not explicitly stated, but "three separate Physician Office Laboratory (POL) sites and in-house over five days" implies multiple replicates per site and day.
- Accuracy (Correlation Study): 95 samples with CK values ranging from 32 to 1181 U/L.
- Accuracy (Patient Correlation Studies): Not explicitly stated, but performed at "three separate POL sites."
- Sensitivity: Not explicitly stated, but the "detection limit" is a single value derived from testing.
- Precision:
- Data Provenance: The document does not explicitly state the country of origin. The test for precision was conducted both in-house and at three Physician Office Laboratory (POL) sites. The accuracy studies were also conducted in a similar fashion. It is implied to be a prospective study as this is performance data reported for submission.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of device (Clinical Analyzer for Creatine Kinase) does not typically involve human experts establishing a "ground truth" for the test set in the same way an imaging or diagnostic AI device does. The ground truth for such devices is established by a "comparative method" (a reference laboratory method or an established, legally marketed device against which the new device's performance is measured).
Therefore:
- Number of Experts: Not applicable in the context of typical AI device ground truth.
- Qualifications of Experts: Not applicable.
4. Adjudication Method for the Test Set
Not applicable. For a clinical analyzer, the "ground truth" is determined by a comparative laboratory method, not by human expert adjudication of individual case results.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, an MRMC comparative effectiveness study was not done. This type of study is relevant for imaging or diagnostic AI devices where human readers interpret results, and the AI might assist in that interpretation. The S-Test CK is a clinical analyzer for quantitative determination of an analyte, not an AI-assisted diagnostic tool that humans interpret visually.
6. Standalone (i.e., algorithm only without human-in-the-loop performance) Study
Yes, the studies described are standalone performance evaluations of the S-Test CK reagent and S40 Clinical Analyzer system. The device itself performs the quantitative measurement of CK activity. There is no human interpretation "in the loop" that would alter the device's numerical output for the specified performance metrics.
7. Type of Ground Truth Used
The ground truth for the accuracy studies was established by a comparative method. This refers to an established, presumably FDA-cleared or gold-standard laboratory assay for creatine kinase. The document states: "assayed on the S40 Clinical Analyzer using S-Test CK (y) and a comparative method (x)."
8. Sample Size for the Training Set
The document does not provide information about a "training set" in the context of machine learning. This device is a traditional in-vitro diagnostic (IVD) measurement system, not a machine learning or AI-based device that requires a separate training set for algorithm development. The "training" for such devices typically refers to the development and optimization of the chemical reagents and instrument calibration, which is not usually reported with specific sample sizes in this manner.
9. How the Ground Truth for the Training Set Was Established
Not applicable. As explained in point 8, this is not an AI/ML device requiring a training set with established ground truth. The "ground truth" related to the performance of the system would be established through internal R&D and validation processes using reference materials and comparative methods, but this is part of the product development rather than a labeled "training set" for an algorithm.
§ 862.1215 Creatine phosphokinase/creatine kinase or isoenzymes test system.
(a)
Identification. A creatine phosphokinase/creatine kinase or isoenzymes test system is a device intended to measure the activity of the enzyme creatine phosphokinase or its isoenzymes (a group of enzymes with similar biological activity) in plasma and serum. Measurements of creatine phosphokinase and its isoenzymes are used in the diagnosis and treatment of myocardial infarction and muscle diseases such as progressive, Duchenne-type muscular dystrophy.(b)
Classification. Class II.