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The DRI™ Tricyclics Serum Tox Assay is a homogeneous enzyme immunoassay intended for the qualitative and/or semiquantitative determination of the presence of tricyclic antidepressants (TCAs) in human serum, plasma, or urine of patients at a cutoff concentration of 300 ng/mL in patients suspected of drug overdose.

The semi-quantitative mode is for the purpose of enabling laboratories to determine an appropriate dilution of the specimen for confirmation by a confirmatory method such as Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS) or permitting laboratories to establish quality control procedures.

The assay provides only a preliminary analytical test result. A more specific alternative chemical 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 DRI™ Tricyclics Serum Tox Assay is a homogeneous enzyme immunoassay using ready to-use liquid reagents. Specific tricyclic antibodies were used to detect most tricyclic antidepressants in serum, plasma, or urine. The test is based on the competition of an enzyme, glucose-6-phosphate dehydrogenase (G6PDH), labeled-drug and the drug from the sample for a fixed amount of specific antibody binding sites. In the absence of the drug from the sample, the specific antibody binds the enzyme-labeled drug and the enzyme activity is inhibited. This phenomenon creates a direct relationship between drug concentration in the sample and the enzyme activity. The enzyme activity is determined spectrophotometrically at 340 nm by measuring its ability to convert nicotinamide adenine dinucleotide (NAD) to NADH.

The DRI™ Tricyclics Serum Tox assay is supplied as a two liquid reagent kit (Reagent A and Reagent E). Thev are bottled separately within the same kit, see details below:

• Antibody/Substrate Reagent (Reagent A): 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 (Reagent E): Contains glucose-6-phosphate ● dehydrogenase (G6PDH) labeled with nortriptyline in Tris buffer with sodium azide as a preservative.

The provided document describes the analytical performance of the DRI™ Tricyclics Serum Tox Assay. It details various studies conducted to demonstrate its performance characteristics, but it does not explicitly state specific pass/fail acceptance criteria for each test. Instead, it presents the results of each study, implying that these results met the internal criteria used by the manufacturer for demonstrating sufficient performance and substantial equivalence to the predicate device.

Here's an analysis of the provided information, addressing your points where possible, and noting when the information is unavailable:

1. A table of acceptance criteria and the reported device performance

As mentioned, explicit acceptance criteria (e.g., "Accuracy must be >95%") are not stated in this document. The tables below summarize the reported device performance for several key analytical studies. The implication is that these reported performances were deemed acceptable for the 510(k) clearance.

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Precision (Repeatability): 80 replicates per concentration level for serum and urine.
• Precision (Reproducibility): 75 replicates per concentration level for serum and urine (across 3 different instruments, 2 reagent lots).
• Spike Recovery: 20 replicates for low and high controls for both serum and urine.
• Dilution Linearity: 9 levels, each with 5 replicates, for both serum and urine.
• Method Comparison and Accuracy:
  • Serum: 61 negative patient samples + 56 positive patient samples = 117 total patient samples.
  • Urine: 50 negative patient samples + 50 positive patient samples = 100 total patient samples.
• Matrix Equivalency: 50 patient samples for each of 5 plasma types (K2 EDTA, K3 EDTA, Lithium Heparin, Sodium Citrate, Potassium Oxalate), and 45 patient samples for Sodium Heparin plasma. Each run with 2 replicates.
• Specificity (Cross-Reactivity) & Interference: Tested with known spiked concentrations in drug-free serum/urine and low/high controls. The exact number of individual samples/replicates for each substance is not explicitly stated beyond what is in the tables (e.g., "known amount," "single determinations" implied for cross-reactivity at a given concentration).
• Data Provenance: The document does not specify the country of origin of the data or whether the patient samples were collected retrospectively or prospectively.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

This device is an in vitro diagnostic (IVD) assay for detecting tricyclic antidepressants. The ground truth for the test set (method comparison study) was established by comparison to Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS) lab testing. This is a highly accurate analytical chemical method, considered the "preferred confirmatory method" by the device's indications for use. Therefore, human experts were not used to establish the primary ground truth in the way they might be for image-based diagnostics. The LC-MS/MS results serve as the objective reference standard.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not applicable, as the ground truth was based on a reference chemical analytical method (LC-MS/MS), not on human expert adjudication.

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

Not applicable. This is an IVD assay, not an AI-based diagnostic tool requiring human interpretation or a multi-reader study.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Yes, the studies presented are standalone performance studies of the device (the assay) itself. There is no human-in-the-loop component for the analytical performance evaluations described. The device provides a preliminary analytical test result independently.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

The ground truth for all analytical performance studies (especially method comparison) was Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS), which is a gold-standard chemical analytical method.

8. The sample size for the training set

This document describes the analytical validation of an enzyme immunoassay kit, not a machine learning algorithm. Therefore, there is no "training set" in the context of AI/ML. The samples used for various analytical performance studies (precision, spike recovery, linearity, method comparison, etc.) are implicitly part of the validation process, not for "training" an algorithm.

9. How the ground truth for the training set was established

As there is no training set for a machine learning algorithm, this question is not applicable. The assay's performance is based on its biochemical interaction, not on learned patterns from a training dataset.

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