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The RapidFRET Oral Fluid Assay for Methamphetamine is a homogeneous time-resolved fluorescence assay that is intended for prescription use in central laboratories only on the RapidFRET Integrated Workstation. The assay is used to perform a qualitative screen for methamine at 50 ng/mL in neat oral fluid samples collected with the RapidEASE Oral Fluid Collector. This assay provides only a preliminary result. To obtain a confirmed analytical result, a more specific alternate chemical method such as GC/MS or LC/MS/MS is required. Professional judgment should be applied to any drug test result, particularly when using preliminary positive results. For In Vitro Diagnostic Use Only.

The RapidFRET Oral Fluid Methamine Calibrators and RapidFRET Oral Fluid Methamphetamine Controls are intended for use only with appropriate RapidFRET Oral Fluid Assay products and samples collected with the RapidEASE Oral Fluid Collector. The cutoff calibrator is used to determine the cutoff level and translate the assay measurement into a positive or negative result. The positive controls are used to monitor laboratory systems, operators, precision. accuracy and assay conditions. For In Vitro Diagnostic Use Only.

The RapidFRET Oral Fluid Assay for Methamphetamine is an In Vitro Diagnostic competitive immunoassay used to detect methamphetamine in human oral fluid. This is a ready-to-use homogenous system that involves energy transfer between an acceptor fluorophore labeled to an antibody and a donor fluorophore labeled to drug. The assay is based on competition between drug in the sample and drug labeled with the donor fluorophore for a fixed number of binding sites on the antibody reagent. When acceptor and donor fluorophores are brought into close proximity through a binding event, energy transfer occurs. The fluorescence resonance energy transfer (FRET) signal is measured at the wavelength of the acceptor fluorophore and is inversely proportional to the amount of drug in the sample. A Cutoff Calibrator is used to translate the sample measurement into a positive or negative result. Controls are used to establish and monitor precision and accuracy.

The provided text describes the RapidFRET Oral Fluid Assay for Methamphetamine. Here's an analysis of the acceptance criteria and the study conducted:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state formal "acceptance criteria" through a defined table or specific performance thresholds for sensitivity, specificity, or accuracy that the device must meet. Instead, the performance characteristics are presented as results from various studies, which imply the expected performance for a successful premarket notification. The de facto acceptance criteria appear to be substantial equivalence to the predicate device (Lin-Zhi International, Inc., LZI Oral Fluid Methamphetamine Enzyme Immunoassay (K131652)) and demonstrating acceptable analytical performance.

However, based on the provided data, we can infer some performance expectations and list the reported outcomes:

2. Sample Size and Data Provenance

• Analytical Sensitivity & Precision:

  • Sample size: 264 per concentration level (total 9 concentrations x 264 samples = 2376 test results) for the aggregate data table, across 3 lots and 20+ non-consecutive days. This refers to spiked negative oral fluid samples, not patient samples.
  • Data provenance: Not explicitly stated, but based on "negative oral fluid spiked," it is laboratory-generated data.

• Correlation with MS Quantitation (Accuracy):

  • Sample size: 92 oral fluid samples (from volunteers).
  • Data provenance: Retrospective for analysis, but the samples were "collected with the RapidEASE Oral Fluid Collection Device from volunteers potentially positive and negative for methamphetamine." This suggests a prospective collection for this specific study, but then subjected to retrospective analysis with blinding. Country of origin not specified.

• Cross-Reactivity and Analytical Specificity:

  • Sample size: Not explicitly detailed by number of samples, but involved a "compound library" and various common substances, each spiked into "neat oral fluid pool aliquots."
  • Data provenance: Laboratory-generated data using spiked oral fluid.

3. Number of Experts and Qualifications for Ground Truth

• For the "Correlation with MS Quantitation" study, the ground truth was established by confirmatory testing using "a more specific alternate chemical method such as GC/MS or LC/MS/MS." These are analytical chemistry techniques, not typically interpreted by "experts" in the human sense (e.g., radiologists). The "experts" here would be the laboratory personnel operating and interpreting the results of the GC/MS or LC/MS/MS, who are typically highly trained analytical chemists or toxicologists. The number and qualifications are not specified in the document.

4. Adjudication Method for the Test Set

• For the "Correlation with MS Quantitation" study, the adjudication method was comparison against the results of GC/MS or LC/MS/MS. This is a direct comparison to a gold standard, so no human adjudication (e.g., 2+1, 3+1 consensus reading) of the device's results was described or necessary. The samples were "randomized and blinded to the instrument operator" for the RapidFRET assay.

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

• No, an MRMC comparative effectiveness study was not done. This device is an in vitro diagnostic (IVD) assay; its performance is measured analytically rather than by human readers interpreting images or data. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply.

6. Standalone Performance

• Yes, a standalone performance study was done. The entire Brief Description of Study Data section (Precision, Analytical Sensitivity, Correlation with MS Quantitation, Cross-Reactivity, Analytical Specificity) describes the performance of the RapidFRET Oral Fluid Assay device itself, without human interpretation or intervention in the diagnostic decision-making process beyond initial sample handling and instrument operation. The device provides a qualitative "positive" or "negative" screen based on its internal cutoff.

7. Type of Ground Truth Used

• Analytical True Value / Confirmatory Test Results:
  • For Analytical Sensitivity and Precision, the ground truth was the known concentration of d-methamphetamine spiked into negative oral fluid.
  • For Correlation with MS Quantitation, the ground truth was established by GC/MS or LC/MS/MS results, considered the gold standard for confirmatory drug testing.
  • For Cross-Reactivity and Analytical Specificity, the ground truth was the known composition and concentration of spiked compounds.

8. Sample Size for the Training Set

• This device is an immunoassay, not a machine learning or AI-based device that requires a "training set" in the conventional sense. The "training" of an immunoassay is more akin to assay development and optimization to achieve desired sensitivity and specificity, using reagents and chemical principles. Hence, there is no discrete "training set" sample size like a deep learning model would have. The document describes analytical validation studies, not AI model development.

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

• As noted above, this concept doesn't directly apply to this type of immunoassay. The development and optimization of the assay (which could be considered analogous to "training") would involve establishing the expected reactivity of the antibodies and drug conjugates, and setting the cutoff calibrator, typically through extensive laboratory experimentation using precisely known concentrations of analytes and interferents.

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