(148 days)
The Axis ® %CDT Turbidimetric Immunoassay (TIA) is intended for the quantitative measurement of carbohydrate deficient transferrin (CDT) in human serum, as a tool to identify possible chronic heavy alcohol consumption.
The Axis ® %CDT Turbidimetric Immunoassay is designed for the quantitative determination of carbohydrate deficient transferrin (CDT) in human serum.
The Axis® %CDT is a heterogeneous immunoassay with column separation followed by turbidimetric measurement. Serum transferrin in the sample is saturated with Fe ". The mixture is applied to an ion-exchange column. Due to the different amounts of sialic residues on transferrin, the isoforms carry different charges and are separated in the column. The CDT isoforms are eluted. The CDT content of the collected eluate is determined by turbidimetric measurement.
The eluted CDT isoforms form immune complexes with anti-transferrin antibodies. Total transferrin content of the sample is determined separately, using the same anti- transferrin antibodies. The measurements are evaluated using a calibration curve, and the Axis® %CDT value is calculated.
The Axis® %CDT Turbidimetric Immunoassay (TIA) is designed for the quantitative determination of carbohydrate deficient transferrin (CDT) in serum to identify possible chronic heavy alcohol consumption.
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria Category | Specific Criteria | Reported Device Performance | Comments |
|---|---|---|---|
| Clinical Performance (vs. GGT) | Sensitivity at 5% CDT cut-off | Males: 0.70 | |
| Females: 0.55 | Compared to Gamma-glutamyl transferase (GGT) | ||
| Specificity at 5% CDT cut-off | Males: 0.93 | ||
| Females: 0.91 | Compared to GGT | ||
| Correlation with GGT | Low and not significant | Consistent with literature | |
| Area Under the Curve (ROC) | Identical to GGT for all subjects (combined genders) | Suggests similar overall diagnostic accuracy | |
| AUC for Males | Slightly better for CDT than GGT | ||
| AUC for Females | Slightly better for GGT than CDT | ||
| Precision | Within-run CV (low control) | 4.8% | NCCLS document EP5-T2 followed |
| Within-run CV (high control) | 2.7% | ||
| Total Precision (low control) | 6.4% | ||
| Total Precision (high control) | 3.4% | ||
| Analytical Sensitivity | Limit of Detection (LOD) | 1.0 mg/L transferrin | |
| Limit of Quantification (LOQ) | 1.0 mg/L CDT and 1.5 mg/L total transferrin | ||
| Linearity | Measuring Range | 0 - 50 mg/mL | |
| Accuracy | Correlation with HPLC %CDT (r) | 0.96 | Comparison to a recognized gold standard |
| Slope vs. HPLC %CDT | 1.12 | ||
| Y-Intercept vs. HPLC %CDT | -0.15 | ||
| Interference | Hemoglobin interference | 10% for concentrations above 10g/L | Note: Interference observed at high lipid levels |
| Plasma vs. Serum | Significantly higher %CDT in plasma | Sample type impact | |
| Drug interference | No effect on CDT level | ||
| Hook effect (Total Transferrin) | Critical at > 100mg/L; no clinical consequence | Human TT values are far below this level | |
| Temperature Sensitivity | Low control %CDT (18°C, 25°C, 30.5°C) | 2.5%, 4.9%, 8.3% respectively | Indicates temperature dependence |
| High control %CDT (18°C, 25°C, 30.5°C) | 8.3%, 9.5%, 11.2% respectively | Indicates temperature dependence |
2. Sample Size Used for the Test Set and Data Provenance:
The document does not explicitly state the exact sample size for the test set used in study CT-C8001. It describes the study group as "social drinkers and in chronic heavy drinkers," differentiating between males and females in the performance analysis.
The data provenance is not explicitly stated in terms of country of origin. The study appears to be retrospective as it analyzes associations between CDT, GGT, and drinking habits.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
The document does not specify the number or qualifications of experts used to establish the ground truth for the test set.
4. Adjudication Method for the Test Set:
The document does not describe an adjudication method for the test set. The ground truth appears to be based on "social drinkers" vs. "chronic heavy drinkers" which would typically be established through self-reporting or clinical assessment, but the method for confirming these classifications is not detailed.
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 device is an in vitro diagnostic (IVD) immunoassay, not an AI-powered diagnostic imaging or interpretation tool designed to assist human readers. Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable and was not performed.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:
Yes, the study describes the standalone performance of the Axis® %CDT TIA. The reported sensitivities, specificities, and AUC values are for the device itself, not in conjunction with human interpretation or intervention for the actual measurement. The calculation of %CDT from measured concentrations is an intrinsic function of the assay.
7. The Type of Ground Truth Used:
The ground truth appears to be a clinical classification based on behavioral and lifestyle factors: "social drinkers" and "chronic heavy drinkers." While not specified, these classifications are typically established through patient history, questionnaires, or other clinical assessments rather than pathology or direct outcomes data provided within this summary.
8. The Sample Size for the Training Set:
The document does not explicitly mention a separate "training set" or its sample size. The description pertains to the overall clinical study (CT-C8001) which evaluates the device's performance in different drinking groups. It's possible the entire dataset was used for evaluation, or aspects of the assay development were done with internal data not detailed here.
9. How the Ground Truth for the Training Set Was Established:
As no explicit training set is mentioned, the method for establishing ground truth for a training set is not provided. If the clinical study data was also used for "training" or refinement, the ground truth would have been established by classifying individuals as "social drinkers" or "chronic heavy drinkers" as described above (likely based on self-reported alcohol intake or clinical assessment for drinking patterns).
§ 862.1360 Gamma-glutamyl transpeptidase and isoenzymes test system.
(a)
Identification. A gamma-glutamyl transpeptidase and isoenzymes test system is a device intended to measure the activity of the enzyme gamma-glutamyl transpeptidase (GGTP) in plasma and serum. Gamma-glutamyl transpeptidase and isoenzymes measurements are used in the diagnosis and treatment of liver diseases such as alcoholic cirrhosis and primary and secondary liver tumors.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 862.9.