(221 days)
The Alinity c Tricyclic Antidepressants Reagent Kit is a homogeneous enzyme immunoassay intended for use in the qualitative and/or semiquantitative determination of the presence of tricyclic antidepressants (TCAs) in human serum or plasma at a cutoff concentration of 300 ng/mL on the Alinity c system in patients suspected of drug overdose.
The semiquantitative mode is for the purpose of enabling laboratories to determine an appropriate dilution of the specimen for confirmation by confirmatory method such as Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS), or for permitting laboratories to establish control procedures.
The assay provides only a preliminary analytical test result. A more specific alternative chemical method must be used to obtain a confirmed analytical result. Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS) is the preferred confirmatory method.
Clinical and professional judgment should be applied to any drug of abuse test result, particularly when preliminary positive results are used.
For In Vitro Diagnostic Use Only.
The Alinity c Tricyclic Antidepressants Reagent Kit is an automated clinical chemistry assay and a homoqeneous enzyme immunoassay using ready-to-use liquid reagents. The assay uses polyclonal antibodies that detect most tricyclic antidepressants in serum or plasma. The assay is based on the competition between an enzyme-labeled drug and the drug from the serum or plasma for a fixed number of specific antibody binding sites. In the absence of drug from the sample, the specific antibody binds to the drug labeled with glucose-6-phosphate dehydrogenase (G6PDH) and the enzyme activity is inhibited. This phenomenon creates a direct relationship between the drug concentration in the serum or plasma and the enzyme activity. The G6PDH enzyme activity is determined spectrophotometrically at 340/416 nm by measuring its ability to convert nicotinamide adenine dinucleotide (NAD) to NADH.
The Alinity c Tricyclic Antidepressants Reagent Kit is supplied as a two liquid reagent kit (R1 and R2). They are included within the same kit, see details below:
- Antibody/Substrate Reagent (R1): Contains polyclonal anti-tricyclics antibodies ● (sheep), glucose-6- phosphate (G6P), and nicotinamide adenine dinucleotide (NAD) in Tris buffer with sodium azide as a preservative.
- Enzyme Conjugate Reagent (R2): Contains glucose-6-phosphate dehydrogenase (G6PDH) labeled with nortriptyline in Tris buffer with sodium azide as a preservative.
Here's the breakdown of the acceptance criteria and study information for the Alinity c Tricyclic Antidepressants Reagent Kit, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The document doesn't explicitly state "acceptance criteria" as a separate predefined table for each test. Instead, the performance studies themselves imply the acceptance criteria by demonstrating successful results within expected ranges for each analytical parameter. I've synthesized these based on common analytical performance expectations and the reported findings.
| Study Parameter | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| a) Precision (Repeatability) | Consistent qualitative/semi-quantitative results across replicates and runs. No significant outliers. | At or below -25% cutoff (225 ng/mL), all 80 replicates were Negative. At or above +25% cutoff (375 ng/mL), all 80 replicates were Positive. At cutoff (300 ng/mL), 54/26 (Qualitative) and 56/24 (Semi-Quantitative) Negative/Positive results respectively. |
| a) Precision (Reproducibility) | Consistent qualitative/semi-quantitative results across multiple instruments, lots, and runs. | At or below -25% cutoff (225 ng/mL), all 75 replicates were Negative. At or above +25% cutoff (375 ng/mL), all 75 replicates were Positive. At cutoff (300 ng/mL), 40/35 (Qualitative) and 49/26 (Semi-Quantitative) Negative/Positive results respectively. |
| b) Spike Recovery | Accurate detection of spiked low and high control samples. | Low Control (225 ng/mL): All 20 replicates were Negative. High Control (375 ng/mL): All 20 replicates were Positive. No overlap between low and high controls. |
| c) Dilution Linearity | Mean Recovery (%) generally within an acceptable range (e.g., 80-120%). | Mean recovery values ranged from 98% to 118% across 9 concentration levels (0 to 500 ng/mL). |
| d) Method Comparison and Accuracy (Serum) | High agreement with LC-MS/MS, especially near and above cutoff. Low false positive/negative rates. | % Negative Sample Agreement: 96% (48/50). % Positive Sample Agreement: 100% (50/50). % Total Sample Agreement: 98% (98/100). |
| e) Matrix Equivalency | Consistent qualitative/semi-quantitative results across different plasma matrices compared to serum. | K2 EDTA, K3 EDTA, Lithium Heparin, Sodium Citrate, Potassium Oxalate, and Sodium Heparin Plasma all showed 25 Positive and 25 Negative results, matching the expected outcome based on the spiked samples. |
| f) Specificity (Cross-Reactivity) | Predictable cross-reactivity with structurally related compounds as expected for TCA assays. Minimal to no clinically significant cross-reactivity with structurally unrelated compounds. | Structurally Related TCAs: Wide range of cross-reactivity (e.g., Amitriptyline 100%, Imipramine 157.9%, Desipramine 107.1%). Other Drugs: Varied cross-reactivity for some (e.g., Chlorpromazine 60%, Cyclobenzaprine 80%), indicating potential for interference. Structurally Unrelated Compounds: Minimal cross-reactivity at specified concentrations, with no impact on samples spiked at -25% and +25% of cutoff. Carbamazepine noted as a specific limitation causing unconfirmed positive results at high concentrations (>3000 ng/mL). |
| g) Interference | Endogenous and exogenous substances should not interfere with accurate qualitative/semi-quantitative results. | Controls (225 ng/mL and 375 ng/mL) were detected accurately (Negative and Positive, respectively) in the presence of tested conjugated/unconjugated bilirubin, hemoglobin, HSA, y-globulin, Rh Factor, triglycerides, and cholesterol at specified concentrations. |
2. Sample Size Used for the Test Set and Data Provenance
- Precision Studies (Repeatability): 80 replicates for each of 7 concentration levels (total 560 samples) for qualitative and semi-quantitative modes.
- Precision Studies (Reproducibility): 75 replicates for each of 7 concentration levels (total 525 samples) for qualitative and semi-quantitative modes.
- Spike Recovery: 20 replicates for Low Control (225 ng/mL) and 20 replicates for High Control (375 ng/mL).
- Dilution Linearity: 5 replicates for each of 9 concentration levels (total 45 samples).
- Method Comparison and Accuracy: 50 negative and 50 positive patient specimens (total 100 patient specimens).
- Matrix Equivalency: 50 patient samples (analyzed in 2 replicates each, across 6 different plasma matrices).
- Specificity (Cross-Reactivity): Varies per compound, generally by spiking known amounts into drug-free serum.
- Interference: Low control (225 ng/mL) and high control (375 ng/mL) samples were spiked with various interfering substances.
Data Provenance: The document does not explicitly state the country of origin for the data or whether the patient specimens were retrospective or prospective. It refers to "patient specimens" without further detail on their origin or collection method.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document states that the test results were "Compared to LC-MS/MS lab testing." LC-MS/MS (Liquid Chromatography/Tandem Mass Spectrometry) is generally considered the gold standard confirmatory method for drug analyses. Therefore, the ground truth was established by this highly specific and sensitive analytical technique, rather than by human expert consensus or pathology in the traditional sense. The document does not specify the number or qualifications of individuals who performed or interpreted the LC-MS/MS tests; it's assumed to be performed by qualified laboratory personnel.
4. Adjudication Method (for the test set)
Ground truth was established by LC-MS/MS, which is an objective chemical analysis method. Therefore, no human adjudication method (like 2+1 or 3+1) was used or needed for establishing the ground truth. Discordant samples were further investigated using additional LC-MS analysis to assess the root cause, indicating a scientific investigation of discrepancies rather than a consensus-based adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was done. This device is an automated clinical chemistry assay, an in vitro diagnostic (IVD) reagent kit, and not an AI-powered diagnostic imaging device involving human readers. Therefore, there's no "human readers improve with AI vs. without AI assistance" effect size to report.
6. Standalone Performance Study
Yes, a standalone performance study was done. All the analytical performance studies (Precision, Spike Recovery, Dilution Linearity, Method Comparison, Matrix Equivalency, Specificity, Interference) evaluate the performance of the Alinity c Tricyclic Antidepressants Reagent Kit (i.e., the algorithm/reagent system) independently. The results reported are the performance of the device without human interpretation affecting the primary quantitative or qualitative output of the assay.
7. Type of Ground Truth Used
The primary ground truth used for performance evaluation, particularly for method comparison and accuracy, was LC-MS/MS (Liquid Chromatography/Tandem Mass Spectrometry) results. LC-MS/MS is considered a definitive confirmatory method for drug concentrations.
8. Sample Size for the Training Set
The document does not provide information about a "training set" in the context of machine learning or AI. This device is described as a "homogeneous enzyme immunoassay" using "polyclonal antibodies." This indicates a traditional biochemical assay technology, not a machine learning model that requires a dedicated training set. Therefore, this question is not applicable to the technology described.
9. How the Ground Truth for the Training Set Was Established
As noted in point 8, this device does not appear to be an AI/ML-based system requiring a training set. If there were any internal development or calibration processes that involved data, the document does not specify them or their ground truth establishment. For traditional IVD assays, performance is typically validated against reference methods and known standards.
§ 862.3910 Tricyclic antidepressant drugs test system.
(a)
Identification. A tricyclic antidepressant drugs test system is a device intended to measure any of the tricyclic antidepressant drugs in serum. The tricyclic antidepressant drugs include imipramine, desipramine, amitriptyline, nortriptyline, protriptyline, and doxepin. Measurements obtained by this device are used in the diagnosis and treatment of chronic depression to ensure appropriate therapy.(b)
Classification. Class II (special controls). A tricyclic antidepressant drugs test system is not exempt if it is intended for any use other than employment or insurance testing or is intended for Federal drug testing programs. The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 862.9, provided the test system is intended for employment and insurance testing and includes a statement in the labeling that the device is intended solely for use in employment and insurance testing, and does not include devices intended for Federal drug testing programs (e.g., programs run by the Substance Abuse and Mental Health Services Administration (SAMHSA), the Department of Transportation (DOT), and the U.S. military).