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The Amphetamine-Specific Enzyme Immunoassays for Drugs of Abuse in Oral Fluid is a homogeneous enzyme immunoassay system to detect amphetamine in human saliva with a cutoff of 45 ng/mL when testing oral fluid specimen collected with Salivette collector (manufactured by Sarstedt) and diluted with 1 mL of buffer. The calibrators and controls of the analyte (d-amphetamine) are prepared with oral fluid buffer so that it can be used to verify and validate the assay. The assay is intended for use in the qualitative determination for amphetamine. The assay is designed for professional use with a number of automated clinical chemistry analyzers.

The Oral Fluid Amphetamine-Specific Enzyme Immunoassay is a homogeneous enzyme immunoassay system provides only a preliminary analytical test result. A more specific alternative chemical method must be used to obtain a confirmed analytical result. Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method. Clinical consideration and professional judgment should be applied to any drug-of-abuse test result, particularly when preliminary positive results are used.

LZI's Oral Fluid Amphetamine-Specific Enzyme Immunoassay is a ready-to-use, liquid reagent, homogeneous enzyme immunoassay. The assay uses specific antibodies that can detect amphetamine in oral fluid with minimal cross-reactivity to various, common prescription drugs and abused drugs. The assay is based on competition between drug labeled with glucose-6-phosphate dehydrogenase (G6PDH) enzyme and free drug from the saliva sample for a fixed amount of specific antibody. In the absence of free drug from the saliva sample the specific antibody binds to the drug labeled G6PDH enzyme causing a decrease in enzyme activity. It is therefore the drug concentration is proportional to the enzyme activity. The G6PDH enzyme activity is determined spectrophotometrically at 340 nm by measuring its ability to covert nicotinamide adenine dinucleotide (NAD) to NADH.

Here's a summary of the acceptance criteria and study details for the LZI Oral Fluid Amphetamine-Specific Homogeneous Enzyme Immunoassay based on the provided 510(k) summary:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the comparison to the predicate device and the reported performance characteristics. The primary acceptance criterion appears to be achieving a high agreement rate with the Gas Chromatography/Mass Spectrometry (GC/MS) confirmatory method for clinical samples, along with acceptable precision.

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

• Sample Size for Test Set:
  • Accuracy: n=120 clinical patient samples for the LZI device.
  • Precision: Not explicitly stated as a separate "test set" for precision, rather it seems to be part of the overall performance characterization. For "Within Run Precision", 120 (unspecified units) are mentioned. For "Total Precision", no sample size is given directly.
• Data Provenance: Not explicitly stated (e.g., country of origin). The samples are referred to as "Clinical patients samples," implying they are real-world human samples. The study appears to be prospective in nature for these performance characteristics, as it describes the testing of the newly developed device.

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

Not applicable. The ground truth for this device is established through a laboratory method (GC/MS), not by human expert interpretation of images or other subjective data.

4. Adjudication Method for the Test Set

Not applicable. The ground truth is established by a definitive analytical method (GC/MS), not by expert consensus or adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is an in-vitro diagnostic assay for detecting amphetamine, not an imaging device or AI-assisted diagnostic tool that would involve human readers interpreting cases.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the performance presented for the LZI Oral Fluid Amphetamine-Specific Homogeneous Enzyme Immunoassay is a standalone performance. It measures the analytical performance of the assay itself using clinical samples, without human intervention in the interpretation of the initial assay result. The assay provides a "preliminary analytical test result," and it is noted that a "more specific alternative chemical method must be used to obtain a confirmed analytical result" (GC/MS). This implies the device operates independently to provide the preliminary result.

7. The Type of Ground Truth Used

The type of ground truth used for the accuracy study is Gas Chromatography/Mass Spectrometry (GC/MS). This is explicitly stated as the "preferred confirmatory method" and the method against which the device's accuracy was compared.

8. The Sample Size for the Training Set

Not applicable. This is an immunoassay, not a machine learning or AI-based device that typically requires a distinct "training set" in the computational sense. The device's performance is based on its chemical and enzymatic reactions.

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

Not applicable, as there isn't a "training set" in the context of this type of in-vitro diagnostic device. The assay development would involve optimizing the reagents and reaction conditions, but not "training" on a dataset with established ground truth in the way an AI algorithm is trained.

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