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The Chemtron Biotech, Inc.'s Chemtrue® Single/Multi-Panel Drug Screen Cassette and Dip Card Tests are rapid lateral flow immunoassays for the qualitative detection of up to six of the following drugs in a variety of combinations in human urine. The designated cutoff concentrations of each drug and the calibrators used for these drugs are as follows:

Analyte Abbreviation Calibrator Cutoff Concentration
Benzodiazepines BZO Oxazepam 300 ng/mL
Barbiturates BAR Secobarbital/Pentobarbital 300 ng/mL
Ecstasy MDMA/XTC d,l-Methylenedioxymethamphetamine 500 ng/mL
Methadone MTD Methadone 300 ng/mL
Opiates OPI/MOR Morphine 2000 ng/mL
Oxycodone OXY Oxycodone 100 ng/mL

The Chemtrue® Single/Multi-Panel Drug Screen Cassette and Dip Card Tests are intended for the qualitative detection of drugs of abuse for health care professionals, in vitro diagnostic and Over-The-Counter (OTC) use.

The BAR.BZO and OXY assay will yield preliminary positive results when BAR, BZO, and OXY is ingested at or above therapeutic doses. There are no uniformly recognized drug levels for Barbiturate, Benzodiazepine and Oxycodone in urine. The Chemtrue® Single/Multi-Panel Drug Screen Cassette and Div Card Tests shows the drug was or was not present at the cutoff level. This assay provides only a preliminary analytical test result. A more specific alternate chemical method must be used in order to obtain a confirmed analytical result. Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method for most drugs (HPLC is the preferred confirmatory method for tri-cyclic antidepressants). Clinical consideration and professional judgment should be applied to any drug of abuse test result, particularly when preliminary positive results are indicated.

The Drugs of Abuse (DOA) Screen Panels are one-step lateral flow immunoassays in which chemically labeled drugs (drug-protein conjugates) compete for limited antibody binding sites with drugs that may be present in urine. The test device consists of up to six test strips placed in separate panels of a plastic holder. On each test strip, a drug-protein conjugate is striped on the test band of the membrane - known as the test region (T) and the drug antibody-colloidal gold conjugate pads are placed at one end of the membrane (opposite in morphine). In the absence of drugs in the urine, the solution of the colored antibody-colloidal gold conjugates move along with the sample solution upward chromatographically by capillary action across the membrane to the immobilized drug-protein conjugate zones on the test band region. The colored antibody-gold conjugates then complexes with the drug-protein conjugates to form visible lines. Therefore, the formation of the visible precipitant in the test band occurs when the test urine is negative for the drug. If any drug is present in the urine, the drug/metabolite antigen competes with the drugprotein conjugates on the test band region for the limited antibody on the colored drug antibodycolloidal gold conjugate pad. When a sufficient amount of drug is present in the urine, the drug will saturate the limited antibody binding sites and the colored antibody-colloidal gold conjugate cannot bind to the drug-protein conjugate at the test strip. Therefore, absence of the color band on the test region indicates a preliminary positive result.

A control band with a different antigen/antibody reaction is added to the membrane strip at the control region (C) to indicate that the test has performed properly. This control line is manufactured as a built-in internal control of the test device and should always appear regardless of the presence of drug or metabolite. If the control line does not appear the test cassette should be discarded. The presence of this colored band in the control region also serves 1) as verification that adequate specimen volume is added (flooding, if too much urine is added, or no flow, due to insufficient urine volume), 2) the test device is properly functioning, and 3) as reagent control.

The acceptance criteria for the Chemtrue® Single/Multi-Panel Drug Screen Dip Card / Cassette Tests are implicitly defined by the reported agreement with GC/MS values in the OTC accuracy study, with a target of "greater than 97.8% accuracy" for lay users and "≥97.8% agreement" with GC/MS. The study demonstrates that lay users can perform and interpret the results correctly with the specified accuracy, and that the device's performance is substantially equivalent to the GC/MS reference method.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size for Test Set: The study involved a total of 200 OTC lay-users. 100 lay-users tested the Dip Card format, and 100 lay-users tested the Cassette format. Within each format, the results table shows varying numbers of samples tested for each drug, typically with 30 samples in each category (e.g., "no drug present," "GC/MS Negative," "Near cutoff negative," etc.), suggesting at least ~90 positive and ~90 negative samples per drug per format for GC/MS comparison, plus samples in the near-cutoff ranges. The exact total number of unique urine samples is not explicitly stated but implies a substantial number.
• Data Provenance: The data was generated from "three (3) independent sites" through an "OTC accuracy study." The nationality of the participants is not explicitly stated but, given the FDA submission, it can be inferred to be from the United States. The study appears to be prospective as it involved selecting and having lay-users perform tests.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

• The ground truth for the test set was established using Gas Chromatography / Mass Spectrometry (GC/MS), which is referred to as "the preferred confirmatory method."
• There were no human experts explicitly described as establishing the ground truth for the test results themselves. The "experts" in this context would be the technicians or laboratory personnel operating and interpreting the GC/MS results, whose qualifications are not specified but are implicitly assumed to be trained professionals for performing such confirmatory chemical analyses.

4. Adjudication Method for the Test Set

• No explicit adjudication method (e.g., 2+1, 3+1) for the interpretation of the test device was used in the lay-user study. The lay-users themselves interpreted the results, and their interpretation was compared against the GC/MS ground truth.
• Discordant results were identified and reported with their GC/MS values, but no process of expert re-adjudication of the test device result itself is described. The agreement percentage directly reflects the lay-user interpretation versus GC/MS.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

• No MRMC comparative effectiveness study was done to compare human readers with AI assistance versus without AI assistance. This device is a rapid diagnostic test with a visual interpretation by the user (lay-user in this case), not an AI-powered diagnostic system that assists human readers.

6. Standalone Performance Study

• Yes, a standalone study was done, specifically the "OTC accuracy study." This study evaluated the performance of the algorithm (i.e., the rapid immunoassay device) when interpreted by a human (lay-users) without any additional human-in-the-loop assistance beyond the instructions provided. The device's performance was compared directly to objective GC/MS results. The results presented in Tables 1 and 2 show the direct agreement rates of the device's output (interpreted by lay-users) with the GC/MS reference.

7. Type of Ground Truth Used

• The type of ground truth used was chemical confirmatory method: Gas Chromatography / Mass Spectrometry (GC/MS). For tri-cyclic antidepressants, HPLC is mentioned as the preferred method, but the drugs in this submission primarily relied on GC/MS.

8. Sample Size for the Training Set

• The document does not explicitly state a sample size for a training set. This device is a rapid immunoassay, which does not typically involve a "training" phase in the same way machine learning or AI models do. The device's formulation and design are developed, and then its performance is validated through studies like the one described. The "Analytical sensitivity (Cut-off characteristics), precision (reproducibility), Accuracy (Method comparison study with clinical samples), specificity and stability study data were established in K111322," which was the predicate device. These earlier studies would have involved samples for the initial characterization and validation but are not detailed here as a "training set."

9. How the Ground Truth for the Training Set Was Established

• As there's no explicitly defined "training set" for an AI or machine learning algorithm, this question isn't directly applicable in the context of this immunoassay device. The ground truth for the development and validation of the immunoassay (e.g., for setting cut-off concentrations, verifying specificity) would have been established through controlled studies using spiked samples and clinical samples, with reference methods such as GC/MS. The document refers to "Performance Data" and states that "Analytical sensitivity (Cut-off characteristics), precision (reproducibility), Accuracy (Method comparison study with clinical samples), specificity and stability study data were established in K111322" (the predicate device's submission), implying that these data, likely using GC/MS or similar reference methods, formed the basis for establishing the device's characteristics.

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