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The LZI Oral Fluid Methamphetamine Enzyme Immunoassay is intended for the qualitative and semi-quantitative determination of d-methamphetamine in neat human oral fluid, collected into the LZI Oral Fluid Collector, at the cutoff value 50 ng/mL. The assay is designed for prescription use with a number of automated clinical chemistry analyzers.

The semi-quantitative mode is for purposes of (1) enabling laboratories to determine an appropriate dilution of the specimen for confirmation by a confirmatory method such as GCMS and LCMS or (2) permitting laboratories to establish quality control procedures.

The LZI Oral Fluid Methamphetamine Calibrators are for use as calibrators in the qualitative and semi-quantitative calibration of the LZI Oral Fluid Methamphetamine Enzyme Immunoassay at the cutoff value 50 ng/mL.

The LZI Oral Fluid Methamphetamine Controls are for use as assayed quality control materials to monitor the precision of the LZI Oral Fluid Methamphetamine Enzyme Immunoassay at the cutoff value of 50 ng/mL.

The assay provides only a preliminary analytical result. A more specific alternative chemical method must be used in order to obtain a confirmed analytical result. Gas or liquid chromatography|mass spectrometry (GC|MS or LC|MS) is the preferred confirmatory method). Clinical consideration and professional judgment should be exercised with any drug of abuse test result, particularly when the preliminary test result is positive.

The LZI Oral Fluid Methamphetamine assay is a homogeneous enzyme immunoassay with ready-to-use liquid reagent. The assay is based on competition between drug in the sample and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for a fixed amount of antibody in the reagent. Enzyme activity decreases upon binding to the antibody, and the drug concentration in the sample is measured in terms of enzyme activity. In the absence of drug in the sample, methamphetamine-labeled G6PDH conjugate is bound to antibody, and the enzyme activity is inhibited. On the other hand, when free drug is present in the sample, antibody would bind to free drug, the unbound methamphetamine-labeled G6PDH then exhibits its maximal enzyme activity. Active enzyme converts nicotinamide adenine dinucleotide (NAD) to NADH, resulting in an absorbance change that can be measured spectrophotometrically at 340 nm.

The LZI Oral Fluid Methamphetamine Enzyme Immunoassay is a kit comprised of two reagents, an R1 and R2 which are bottled separately but sold together within the kit.

The R1 solution contains mouse monoclonal anti-methamphetamine antibody, glucose-6phosphate (G6P) nicotinamide adenine dinucleotide (NAD), stabilizers, and sodium azide (0.09%) as a preservative. The R2 solution contains glucose-o-phosphate dehydrogenase (G6PDH) labeled with methamphetamine in buffer with sodium azide (0.09%) as preservative.

The LZI Oral Fluid Methamphetamine Enzyme Immunoassay calibrators and controls designated for use at the 50 ng/mL cutoffs contain 0, 20, 37.5, 50, 62.5, 100, and 140 ng/mL of dmethamphetamine in human oral fluid with sodium azide (0.09%) as preservative. These five calibrators and two controls are sold as individual bottles.

The LZI Oral Fluid Collector is a 50 mL polypropylene collection tube. It is a non-sterile centrifuge tube with a screw-on cap and printed graduations (United Lab Plastics, Catalog#UP2262).

Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state numerical acceptance criteria for qualitative agreement, but "100.0% agreement with positive" and "95.2% agreement with negative" are presented as favorable performance. The precision data indicates 100% concordance with expected results at various concentrations relative to the cutoff.

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

• Test Set Sample Size: "a total of eighty-five (85) clinical unaltered samples" were used for method comparison.
• Data Provenance: The text does not specify the country of origin. It indicates the samples were "clinical unaltered samples," implying they were collected from human subjects in a clinical setting, making them prospective or retrospective clinical samples. The exact nature (prospective vs. retrospective) is not explicitly stated.

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

This type of immunoassay device relies on a "confirmatory method" for establishing ground truth, not typically human expert consensus for individual results.

• Number of Experts: Not applicable in the traditional sense of human consensus.
• Qualifications of Experts: Not applicable. The ground truth is established by analytical methods.

4. Adjudication Method for the Test Set

Not applicable for this type of device where the ground truth is established by a specific analytical method. The device's results are compared directly to the results from the confirmatory method.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This type of study is typically used for image-based diagnostic devices where human readers interpret images. This device is an in-vitro diagnostic assay.

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

Yes, the studies reported are standalone performance studies of the device (immunoassay) itself. The "Immunoassay Result" tables directly show the device's output (Positive/Negative) for given sample concentrations. The method comparison directly evaluates the device against a gold standard analytical method without human interpretation of the device's output other than reading the final result.

7. The Type of Ground Truth Used

The type of ground truth used is an alternative chemical method, specifically Gas or liquid chromatography/mass spectrometry (GC/MS or LC/MS). These are considered the "preferred confirmatory method[s]" for drug detection in oral fluid.

8. The Sample Size for the Training Set

The document does not report a specific sample size for a training set. Immunoassays like this are developed through a different process involving reagent formulation and optimization rather than machine learning training on a large dataset in the way a software algorithm would be. The "within run" and "total precision" studies use 22 and 88 determinations per concentration, respectively, but these are for performance evaluation, not a "training set."

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

Since a "training set" in the context of machine learning is not explicitly mentioned or relevant for this type of device, the method for establishing ground truth for such a set is not described. The device's performance is demonstrated by comparing its results to established analytical methods for clinical samples and spiked samples with known concentrations.

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