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The Psychemedics homogeneous enzyme immunoassay (HEIA) for opiates in hair is an enzyme immunoassay for the preliminary qualitative detection of opiates in human head and body hair using a morphine calibrator at 2 ng morphine/10 mg hair for the purpose of identifying opiate use. This is an in vitro diagnostic device intended exclusively for Psychemedics use only and is not intended for sale to anyone. The Psychemedics homogeneous enzyme immunoassay for opiates in hair provides only a preliminary analytical test result. A more specific alternative chemical must be used in order to obtain a confirmed analytical result. Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/ MS/MS) is the preferred confirmatory method.

The Psychemedics homogeneous enzyme immunoassay (HEIA) for oxycodone in hair is an enzyme immunoassay for the preliminary qualitative detection of oxycodone in human head and body hair using an oxycodone calibrator at 2 ng oxycodone/10 mg hair for the purpose of identifying opioid use. This is an in vitro diagnostic device intended exclusively for Psychemedics use only and is not intended for sale to anyone. The Psychemedics homogeneous enzyme immunoassay for oxycodone in hair provides only a preliminary analytical test result. A more specific alternative chemical must be used in order to obtain a confirmed analytical result. Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/MS/MS) is the preferred confirmatory method.

The homogeneous enzyme immunoassay (HEIA) test consists of two parts; a pre-analytical hair treatment procedure (to extract opioids from the solid hair matrix to form a measurable liquid matrix) and the screening assay, the Psychemedics Opiates HEIA and the Psychemedics Oxycodone HEIA. The screening portion of the test system is based on competition for antibody binding sites between drug in the measurable liquid matrix and drug-labeled recombinant glucose-6-phosphate dehydrogenase (G6PDH). As the antibody binds labeled G6PDH, enzyme activity decreases. In the presence of drug, enzyme activity increases in direct proportion to the drug concentration. Active enzyme reduces nicotinamide adenine dinucleotide (NAD) to NADH in the presence of glucose-6-phosphate (G6P), resulting in an absorbance change that is measured spectrophotometrically.

The Psychemedics Opiates HEIA consists of reagents R1 (anti-opiates monoclonal antibody with substrate) and R2 (morphine labeled recombinant G6PDH). The Psychemedics Oxycodone HEIA consists of reagents R1 (anti-oxycodone monoclonal antibody with substrate) and R2 (oxycodone labeled recombinant G6PDH).

Below you will find the acceptance criteria and study details for the Psychemedics Homogeneous Enzyme Immunoassay (HEIA) for Opiates and Oxycodone in Hair:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly demonstrated by the performance studies showing the device's ability to accurately classify samples as positive or negative compared to LC/MS/MS confirmation, especially at and around the cut-off concentrations. The stated goal for both assays is to provide a "preliminary qualitative detection" of opiates or oxycodone.

The performance is reported in terms of precision (intra-assay and inter-assay), cross-reactivity, and comparison studies against LC/MS/MS.

General Acceptance Criteria (Implied by the study results presented):

• Precision: The assay should reliably produce consistent results for samples at various concentrations around the cutoff, indicating good repeatability and reproducibility. The reported data shows 100% agreement (either all negative or all positive) for samples at different concentrations relative to the cutoff for both intra-assay and inter-assay precision.
• Specificity (Cross-reactivity): The assay should primarily detect the target analytes (opiates or oxycodone) and have minimal cross-reactivity with other structurally similar compounds or common substances. The cross-reactivity tables indicate which compounds show cross-reactivity and at what concentrations. Compounds showing no cross-reactivity are also listed.
• Interference: The assay should not be significantly impacted by common interfering substances, including cosmetic treatments. The study reports no interference from numerous compounds, and also notes which compounds show interference (e.g., imipramine in the oxycodone assay). Cosmetic treatments also did not alter the results for both positive and negative samples.
• Agreement with Confirmatory Method (LC/MS/MS): The preliminary qualitative results should show reasonable agreement with the definitive LC/MS/MS confirmatory method, especially highlighting how the assay performs around the critical cutoff concentration.

Since this is an in vitro diagnostic device for preliminary qualitative detection, the performance metrics (precision, cross-reactivity, and reasonable agreement with a confirmatory method) are the key indicators of acceptance. The device is not intended to be a standalone definitive diagnostic.

Study Details:

1. Sample sizes used for the test set and the data provenance:

   • Psychemedics Opiates HEIA: 230 individual hair samples.
   • Psychemedics Oxycodone HEIA: 219 individual hair samples.
   • Data Provenance: Samples were "collected anonymously from a workplace setting." The document does not specify the country of origin, but given the FDA submission, it's likely primarily U.S. based. The data appears retrospective, as stated "The stored hair samples were then tested..."
   • Precision Studies: Intra-assay precision involved 8 measurements per concentration level, and inter-assay precision involved 80 measurements per concentration level. These were achieved by spiking negative hair with validated calibrator and control solutions.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • No human experts were used for establishing ground truth. The devices being reviewed are in vitro diagnostic devices, which perform quantitative/qualitative analysis.
   • The ground truth was established by Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/MS/MS), which is described as the "preferred confirmatory method" and is a highly sensitive and specific analytical technique for drug detection. This is a chemical/analytical ground truth, not an expert-driven one.

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

   • No human adjudication method was used. The comparison was directly between the test device's preliminary result and the LC/MS/MS confirmatory result.

4. 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 MRMC or human-in-the-loop study was performed. This is an immunoassay, not an AI-assisted diagnostic. Its purpose is to provide a screening result, not to assist human interpretation of complex medical images or data.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Yes, the performance studies described are standalone performance evaluations of the immunoassay itself. The device is an automated chemical analyzer.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • The type of ground truth used was analytical confirmation by Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/MS/MS). For in vitro diagnostic assays measuring chemical substances, this is the gold standard for ground truth.

7. The sample size for the training set:

   • This document describes a 510(k) submission, which typically focuses on demonstrating substantial equivalence through performance testing, not on developing a machine learning model. Therefore, a separate "training set" in the context of AI/ML is not applicable here. The samples used for performance evaluation (230 for Opiates HEIA, 219 for Oxycodone HEIA) are test samples for validation, not a training set. The calibrators and control solutions used in precision studies would be analogous to internal "training" or calibration materials for the assay's function, but not in the sense of a dataset for model training.

8. How the ground truth for the training set was established:

   • As noted above, there isn't a "training set" in the AI/ML context. For the assay's internal calibration and control (which could be considered analogous), the document states: "Psychemedics prepares calibrators and control materials using drug stocks purchased from a commercial vendor. Each lot of drug is received with its specific certificate of analysis. The commercially obtained stock is made into calibrators and controls to the desired concentrations. The concentrations are confirmed by LC/MS/MS." This indicates that the ground truth for the calibrators and controls is also established by LC/MS/MS.

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