(67 days)
This in vitro diagnostic procedure is a solid- phase enzyme immunoassay intended for the quantitative determination of CK-MB in human serum or plasma on the Technicon Immuno 1 system. When used in combination with other clinical data such as presenting symptoms and EKG values, measurement of CK-MB aids in the diagnosis of acute myocardial infarction.
The assay is an enzyme label sandwich assay using two monoclonal antibodies. A CK-MB specific antibody is labelled with fluorescein and the Fab' fragment of an antibody specific for the B subunit is labelled with alkaline phosphatase( ALP) The solid phase consists of a suspension of magnetizable particles coated with antibody to fluorescein ( IMP reagent). Sample or calibrator. R1 reagent containing fluorescein - antibody conjugate, R2 reagent containing ALP-antibody conjugate and IMP reagent are mixed and incubated at 37°C. In the presence of CK-MB a fluorescein-conjugate: CK-MB: ALP-conjugate complex is formed and captured by the anti fluorescein antibodies on the magnetic particles. The particles are washed and pNPP (paranitrophenyl phosphate) substrate is added. The ALP in the antibody conjugate reacts with the pNPP to form para-nitrophenoxide and phosphate. Increasing absorbance due to the formation of paranitrophenoxide is monitored at 405 nm and 450 nm. The dose response curve is directly proportional to the concentration of CK-MB in the sample. A quadratic fit through zero is used to construct the dose response curve.
The assay has a range of 0 to 300 ng/ml and calibrators are provided with values of 0, 5, 10, 30, 100 and 300 ng/ml.
All the results reported herein were obtained by using a quadratic fit through zero algorithm to construct the standard curve.
Here's an analysis of the provided text regarding the acceptance criteria and study for the Immuno 1 CK-MB method:
Understanding the Context:
This document describes the performance of the Immuno 1 CK-MB method, an in vitro diagnostic procedure for measuring CK-MB in human serum or plasma. The primary focus of the provided sections is to demonstrate the comparability and stability of results when using plasma samples as opposed to serum, and to establish storage guidelines.
1. Table of Acceptance Criteria and Reported Device Performance
The document doesn't explicitly state formal "acceptance criteria" in a tabulated format with pass/fail thresholds. Instead, it presents performance data (regression analysis, imprecision, and storage stability) and implicitly suggests that the observed performance validates the use of plasma samples under specified conditions.
Based on the provided data and the intent to show plasma is comparable and stable, here's a table reflecting implied acceptance or expected performance:
| Performance Metric | Implied/Observed Acceptance Criteria (for plasma as alternative to serum) | Reported Device Performance (Plasma vs. Serum) | Reported Device Performance (Plasma Imprecision) | Reported Device Performance (Plasma Stability) |
|---|---|---|---|---|
| Comparability (Plasma vs. Serum) | Regression analysis showing a strong correlation (r close to 1), a slope close to 1, and a small intercept, indicating comparable results between serum and plasma samples. | Site 1: N=45, Range 0.34-24.75 ng/mL, Slope=1.06, Intercept=0.23 ng/mL, r=0.984, Sy.x=1.30 ng/mL | ||
| Site 2: N=60, Range 0.30-334.20 ng/mL, Slope=1.06, Intercept=0.70 ng/mL, r=0.999, Sy.x=2.45 ng/mL | ||||
| Site 3: N=55, Range 0.64-202.36 ng/mL, Slope=1.06, Intercept=0.56 ng/mL, r=0.995, Sy.x=4.69 ng/mL | ||||
| (Overall: Strong correlation and slopes close to 1 across sites, supporting comparability) | N/A | N/A | ||
| Imprecision (Plasma) | Within-run and Total CVs for plasma samples expected to be comparable to established serum performance, indicating good analytical reliability. "No significant difference between the imprecision obtained for serum or plasma" is stated. | N/A | Plasma Samples (N=10, 3 replicates each): |
- Plasma 1 (Mean 5.61 ng/mL): Within-run CV 2.6%, Total CV 3.2%
- Plasma 2 (Mean 6.65 ng/mL): Within-run CV 2.1%, Total CV 2.8%
- Plasma 3 (Mean 5.28 ng/mL): Within-run CV 2.9%, Total CV 2.6%
- Plasma 4 (Mean 4.48 ng/mL): Within-run CV 2.1%, Total CV 2.4%
- Plasma 5 (Mean 6.14 ng/mL): Within-run CV 1.9%, Total CV 2.1%
- Plasma 6 (Mean 6.03 ng/mL): Within-run CV 1.4%, Total CV 1.7%
- Plasma 7 (Mean 5.23 ng/mL): Within-run CV 2.3%, Total CV 2.3%
- Plasma 8 (Mean 4.27 ng/mL): Within-run CV 2.1%, Total CV 2.3%
- Plasma 9 (Mean 4.51 ng/mL): Within-run CV 2.3%, Total CV 2.4%
- Plasma 10 (Mean 7.27 ng/mL): Within-run CV 2.3%, Total CV 7.4%
Serum Controls (for comparison): - Serum Control 1 (Mean 3.31 ng/mL): Within-run CV 3.3%, Total CV 3.7%
- Serum Control 2 (Mean 12.75 ng/mL): Within-run CV 1.2%, Total CV 1.2%
(Conclusion: Stated there is no significant difference between imprecision for serum and plasma) | N/A |
| Plasma Sample Stability | Results for refrigerated (2-8°C) and frozen (-20°C) plasma samples should remain consistent with immediate testing over specified periods, demonstrating stability for clinical use. An implied acceptable deviation (e.g., within a certain % or SD) from the baseline. | N/A | N/A | Refrigerated (2-8°C): Samples stable for at least 7 days.
Frozen (-20°C): Samples stable for at least 1 month.
(Individual results for 10 samples provided, showing minimal variation over time, supporting the stated stability conclusions) |
2. Sample Sizes Used for the Test Set and Data Provenance
- Comparability Study (Plasma vs. Serum):
- Sample Size:
- Site 1: 45 samples
- Site 2: 60 samples
- Site 3: 55 samples
- Total: 160 samples
- Data Provenance: Retrospective and prospective. "Specimens submitted for CK-MB analysis from patients with suspected acute myocardial infarction" (implying clinical samples). "Only specimens from patients who had both serum and lithium heparin plasma samples drawn at the same time were used." The study was conducted at "three independent sites." The country of origin is not specified, but the context generally suggests a developed country (e.g., US or Europe) where such diagnostics are common.
- Sample Size:
- Imprecision Study (Plasma):
- Sample Size: 10 volunteer blood donations, from which plasma was spiked and aliquoted. Each aliquot was tested in three replicates. So, 10 samples, with 3 replicates per measurement point.
- Data Provenance: Prospective (samples from volunteers specifically for the study). Country of origin not specified.
- Stability Study (Plasma):
- Sample Size: 10 volunteer blood donations (same as imprecision study).
- Data Provenance: Prospective (samples from volunteers specifically for the study). Country of origin not specified.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of information is not applicable to this study. The "ground truth" here is the actual concentration of CK-MB in a sample, a quantitative value determined by the Immuno 1 system itself (or implied by its calibration). This is a measurement performance study, not an diagnostic interpretation study by human experts. The comparison baseline for plasma is serum results on the same device.
4. Adjudication Method for the Test Set
This is not applicable. There is no "adjudication" in the sense of resolving discrepancies between human readers or between an AI and human readers. The study involves comparing quantitative measurements from a diagnostic device.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance
This is not applicable. This is an in vitro diagnostic device performance study, not an AI-assisted diagnostic study involving human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the studies described are standalone performance studies of the Immuno 1 CK-MB method. The method itself is an automated laboratory assay (solid-phase enzyme immunoassay). The algorithm used is to "construct the dose response curve" (a quadratic fit through zero) and process results directly from the instrument's optical readings. There is no human interpretation or intervention in the measurement of CK-MB concentration by the algorithm/device. The "performance" being evaluated is the accuracy, precision, and stability of this automated measurement.
7. The Type of Ground Truth Used
The ground truth used in these studies is the quantitative CK-MB concentration as measured by the Immuno 1 system.
- For the comparability study, the "ground truth" for plasma is effectively established by the corresponding serum samples run on the same system, assuming serum is the validated or reference matrix. The regression analysis aims to show that plasma measurements are equivalent to serum measurements.
- For the imprecision and stability studies, the "ground truth" is the established concentration of the spiked CK-MB in the plasma samples, and the consistency of the device's readings against this established value over time and repeated measurements.
8. The Sample Size for the Training Set
- Training Set for the assay's dose response curve: This is built into the assay's calibration process. Calibrators are provided with values of 0, 5, 10, 30, 100, and 300 ng/mL. So, there are 6 calibration points that form the basis for the quadratic fit.
- No other "training set" in the context of machine learning (AI model training) is mentioned or relevant here, as this is a traditional immunoassay.
9. How the Ground Truth for the Training Set Was Established
The "ground truth" for the calibrators (the training set for the dose-response curve) is established through:
- Known concentrations: The calibrators are prepared with specific, pre-defined concentrations of CK-MB (0, 5, 10, 30, 100, and 300 ng/mL). These concentrations would be meticulously prepared and verified using highly accurate reference methods or gravimetric techniques by the manufacturer (Bayer Corp.).
- These known concentrations are then used to build the standard curve, allowing the system to convert absorbance measurements into quantitative CK-MB concentrations.
§ 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.