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The Emit® II Plus Cocaine Metabolite Assay is a homogeneous enzyme immunoassay with a 150 ng/mL or 300 ng/mL cutoff. The assay is intended for use in the qualitative and semiquantitative analyses of benzoylecgonine (cocaine metabolite) in human urine. Emit® II Plus assays are designed for use with a number of chemistry analyzers.

The Emit® II Plus Cocaine Metabolite Assay 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. Other chemical confirmation methods are available. Clinical consideration and professional judgment should be applied to any drug-of-abuse test result, particularly when preliminary positive results are used.

The Emit II Plus Cocaine Metabolite assay is a homogeneous enzyme immunoassay that qualitatively and semiquantitatively measures benzoylecgonine. The assay has cutoffs of 150 ng/mL and 300 ng/mL benzoylecgonine.

The assay is based on competition between drug in the specimen and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for antibody binding sites. Enzyme activity decreases upon binding to the antibody, so the drug concentration in the specimen can be measured in terms of enzyme activity. Active enzyme converts nicotinamide adenine dinucleotide (NAD) to NADH, resulting in an absorbance change that is measured spectrophotometrically at 340 nm.

The Emit II Plus Cocaine Metabolite Assay consists of two ready-to-use reagents:

Antibody/Substrate Reagent 1
Sheep polyclonal antibodies to benzoylecgonine (2.2 µg/mL), bovine serum albumin, G6P (15 mM), NAD (12 mM), preservatives, and stabilizers

Enzyme Reagent 2
Benzoylecgonine labeled with bacterial G6PDH (0.46 U/mL), HEPES buffer, bovine serum albumin, preservatives, and stabilizers

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1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state "acceptance criteria" for the method comparison studies. However, the reported "Result" for agreement percentages can be interpreted as the performance achieved. Similarly, for precision studies, "Results" indicate the number of negative/positive determinations. For linearity, it's % recovery.

Table 1: Acceptance Criteria and Reported Device Performance

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

• Method Comparison:
  • 150 ng/mL Cutoff: n = 102 native patient urine samples.
  • 300 ng/mL Cutoff: n = 95 native patient urine samples.
  • Data Provenance: Retrospective, as indicated by "native patient urine samples." The country of origin is not specified.
• Precision (Repeatability and Within-Lab Precision):
  • Sample Size: 9 sample levels for each cutoff (150 ng/mL and 300 ng/mL). Each level was determined 80 times (20 days, 2 runs/day, 2 replicates/run). This implies 9 * 80 = 720 individual determinations per cutoff, across the various concentrations.
  • Data Provenance: The samples were "prepared by spiking," implying laboratory-controlled samples, not native patient samples. Data provenance (country of origin) is not specified.
• Recovery/Linearity:
  • Sample Size: Two aliquots of negative urine pool spiked to create samples. Five replicates were tested at each of the 10 concentration levels. This implies 5 * 10 = 50 individual determinations.
  • Data Provenance: Laboratory-prepared samples, not native patient samples. Data provenance (country of origin) is not specified.
• Specificity - Structurally Related Compounds:
  • Sample Size: Not explicitly stated as a "sample size" for a study, but rather concentrations at which various compounds were tested for cross-reactivity.
  • Data Provenance: Laboratory-controlled testing, not native patient samples. Data provenance (country of origin) is not specified.

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

The ground truth for the test set (Method Comparison) was established by Gas Chromatography/Mass Spectrometry (GC/MS). GC/MS is an analytical chemistry technique, not a human expert. Therefore, the concept of "number of experts" and their "qualifications" is not applicable in this context.

4. Adjudication Method for the Test Set

Not applicable. The ground truth was established by an objective analytical method (GC/MS), not through human interpretation or adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

No, an MRMC comparative effectiveness study was not done. This device is an automated in vitro diagnostic assay (an enzyme immunoassay) designed to detect a cocaine metabolite in urine. It does not involve human readers for interpretation, nor does it incorporate AI in a way that would assist human interpretation.

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

Yes, the performance studies described (Method Comparison, Precision, Recovery/Linearity, Specificity) represent standalone performance of the device (assay on the analyzer). The results are generated directly by the Emit® II Plus Cocaine Metabolite Assay on the Beckman Coulter DxC 700 AU Clinical Chemistry Analyzer, without human interpretive input. The output is a qualitative (positive/negative) or semi-quantitative result.

7. The Type of Ground Truth Used

The primary ground truth used for the method comparison study was Gas Chromatography/Mass Spectrometry (GC/MS). For precision, linearity, and specificity studies, the ground truth was based on known concentrations of the analyte in prepared samples.

8. The Sample Size for the Training Set

The document does not describe a "training set" in the context of machine learning or AI. This is a traditional in vitro diagnostic device, not an AI/ML-based device.

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

Not applicable, as there is no "training set" described for this device.

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