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The STC Amphetamine-Specific Intercept™ MICRO-PLATE EIA is intended for use by clinical laboratories in the qualitative determination of amphetamine in oral fluid collected with the Intercept™ DOA Oral Specimen Collection Device. For In Vitro Diagnostic Use.

The STC Amphetamine-Specific Intercept™ MICRO-PLATE EIA is a competitive micro-plate immunoassay for the detection of amphetamine in oral fluid collected with the Intercept™ DOA Oral Specimen Collection Device. Specimen or standard is added to an EIA well in combination with an enzyme-labeled hapten derivative. In an EIA well containing an oral fluid specimen positive for amphetamine, there is a competition between the drug and the enzyme-labeled hapten to bind the antibody fixed onto the EIA wells are then washed, substrate is added, and color is produced. The absorbance measured for each well at 450 mm is inversely proportional to the amount of amphetamine present in the specimen or calibrator/control.

Here's an analysis of the provided text, outlining the acceptance criteria and study details for the STC Amphetamine-Specific Intercept™ MICRO-PLATE EIA:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a numerical or pass/fail format for clinical performance. Instead, it presents various analytical performance characteristics and clinical study results. For the purpose of this response, I infer the "acceptance criteria" based on the comparisons made to the predicate device and the presented study outcomes.

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

• Sample Size for Clinical Test Set:
  • Study 1: 1568 oral fluid samples (retrospectively screened)
  • Study 2: 229 oral fluid and urine specimen pairs (from individuals in a drug rehabilitation clinic)
  • Study 3: 44 oral fluid samples (from 22 individuals who self-reported amphetamine use)
  • Combined for % Agreement Calculation: 53 samples with definitive GC/MS results (21 positive by GC/MS, 32 negative by GC/MS). This is derived from the table: 21 (EIA+GCMS+) + 2 (EIA+GCMS-) + 4 (EIA-GCMS+) + 26 (EIA-GCMS-) = 53.
• Data Provenance: The document does not explicitly state the country of origin for the clinical data.
  • Study 1: Retrospective, randomly screened oral fluid samples.
  • Study 2: Prospective, from individuals in a drug rehabilitation clinic.
  • Study 3: Prospective, from individuals who self-reported amphetamine use.

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

The document does not specify the number or qualifications of experts used to establish the ground truth for the clinical test set. The ground truth was established by Gas Chromatography/Mass Spectrometry (GC/MS), which is a gold standard laboratory confirmation method, inherently implying expert interpretation of the GC/MS results.

4. Adjudication Method for the Test Set

The document does not describe a formal adjudication method (e.g., 2+1, 3+1) for resolving discrepancies between the EIA and GC/MS results. The GC/MS results are treated as the definitive ground truth against which the EIA results are compared.

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 study is for an in-vitro diagnostic device (immunoassay) and does not involve human readers interpreting images or data to be assisted by AI. The device itself performs the detection.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, the studies presented are effectively standalone performance studies for the device. The STC Amphetamine-Specific Intercept™ MICRO-PLATE EIA is an immunoassay kit that provides a quantitative absorbance reading, which is then interpreted qualitatively (positive/negative) based on a cutoff. There is no "human-in-the-loop" once the assay is performed; the result is generated by the device and compared to the established cutoff.

7. The Type of Ground Truth Used

The primary ground truth used for both analytical specificity/cross-reactivity and clinical accuracy was Gas Chromatography/Mass Spectrometry (GC/MS). For analytical studies, spiked concentrations were also used as a defined ground truth.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning or AI models. This is an immunoassay kit, not an AI software. The development and calibration of the assay (e.g., determining optimal antibody concentrations, enzyme conjugates, etc.) would be analogous to a "training phase" in a broader sense, but no specific sample size for such a development phase is provided. The analytical studies (LOD, precision, cross-reactivity) involved specific numbers of samples or replicates used to characterize the assay's performance.

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

Given that this is an immunoassay kit and not an AI/ML device, the concept of a "training set ground truth" as understood in AI is not directly applicable. For the analytical characterization, "ground truth" was established through:

• Known concentrations of amphetamine: For LOD and Precision studies, known concentrations of amphetamine in Oral Fluid Diluent were used.
• Spiked concentrations of structurally related compounds: For Analytical Specificity/Cross-Reactivity, specific concentrations of various compounds were spiked into Oral Fluid Diluent.

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