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The Psychemedics homogeneous enzyme immunoassay for cocaine in hair is an enzyme immunoassay for the preliminary qualitative detection of cocaine in human head and body hair using a cocaine calibrator of 5 ng/10 mg hair for the purpose of identifying cocaine use. This product is intended exclusively for in-house professional use and not for sale to anyone.

The Psychemedics EIA Cocaine Assay provides only a preliminary analytical test results, a more specific alternate chemical method (e.g. LC/MS/MS) must be used. Clinical consideration and professional judgement should be applied to the interpretation of any drug-of-abuse test result.

The homogeneous enzyme immunoassay (HEIA) test consists of two parts; a pre-analytical hair treatment procedure (to extract cocaine from the solid hair matrix to a measurable liquid matrix) and the screening assay, the Psychemedics Cocaine 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 Cocaine HEIA consists of reagents R1 (anti-cocaine monoclonal antibody with substrate) and R2 (cocaine labeled recombinant G6PDH).

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

Device Name: Psychemedics Homogeneous Enzyme Immunoassay for Cocaine in Hair

Indications for Use: Preliminary qualitative detection of cocaine in human head and body hair using a cocaine calibrator of 5 ng/10 mg hair, for identifying cocaine use. Intended for in-house professional use only. Positive results require confirmation with a more specific alternate chemical method (e.g., LC/MS/MS).

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" with specific pass/fail metrics in a table format. Instead, it details various performance studies and their results to demonstrate substantial equivalence to a predicate device. I've extracted the relevant performance metrics and will organize them as an "acceptance criteria" table for clarity, inferring the implied acceptance for each from the reported results ("all good", "no cross-reactivity", "remained positive/negative").

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

• Sample Size for Test Set:

  • Precision Studies: 8 replicates per concentration for Intra-Assay, 80 replicates per concentration for Inter-Assay.
  • Cross-Reactivity/Interference: Not explicitly stated as a number of samples, but presumably multiple replicates for each compound tested.
  • Cosmetic Treatments: 10 negative hair samples and 7 positive hair samples.
  • Comparison Study 1: 215 individual hair samples (123 negative, 92 positive by immunoassay).
  • Comparison Study 2: An "additional set of samples" (unspecified number) for which LC/MS/MS data is available for both unwashed and washed samples. The tables present data for a total of 41 positive samples and 51 negative samples relative to the cutoff (for unwashed LC/MS/MS comparison). The sample characteristics table shows 65 Head hair, 27 Body hair, 79 Male, 13 Female, 47 Brown, 39 Black, 6 Salt/Pepper hair for the combined comparison study. Based on table counts, there were 91 samples in Study 2 (41 positive, 50 negative across various LC/MS/MS comparisons).

• Data Provenance:

  • Comparison Study 1: Samples collected anonymously from a workplace setting.
  • Comparison Study 2: Source of hair (head or body) and other demographics were documented.
  • General indication that materials (drug stocks) are purchased from commercial vendors; calibrators and controls are made in-house.

  The study appears to be retrospective, as "stored hair samples were then tested" and samples were "collected anonymously from a workplace setting" for Study 1, and "additional set of samples were identified using the Psychemedics cocaine microplate assay and the test device" for Study 2.

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

The document refers to LC/MS/MS as the "more specific alternate chemical method" and "confirmatory assay" to establish the ground truth for cocaine presence and concentration. It does not mention human experts establishing the ground truth or their qualifications. The ground truth is analytical/laboratory-based.

4. Adjudication Method for the Test Set

There was no human expert adjudication method mentioned (e.g., 2+1, 3+1). The ground truth was established purely through analytical chemistry (LC/MS/MS testing).

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study was not done. This device is an automated in vitro diagnostic (IVD) assay designed for preliminary detection of a substance. It does not involve human readers interpreting images or data, nor does it aim to show how much human readers improve with AI assistance. The comparison is between the new homogeneous immunoassay and a laboratory confirmation method (LC/MS/MS).

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

Yes, the studies performed are essentially standalone performance evaluations of the device (the immunoassay) against the gold standard (LC/MS/MS). The device operates independently of human interpretation for its initial qualitative result. The "human-in-the-loop" aspect comes only after a positive preliminary result, where a professional judgment along with confirmation by LC/MS/MS is required.

7. The Type of Ground Truth Used

The ground truth used is analytical confirmation by LC/MS/MS (Liquid Chromatography-Mass Spectrometry/Mass Spectrometry). This is a highly specific and sensitive laboratory method for identifying and quantifying substances. For the training set, it is also supported by "certificate of analysis" for the drug stocks.

8. The Sample Size for the Training Set

The document does not explicitly state the sample size used for the training set. The performance studies described are for the validation of the device (effectively the test set). For the calibrators and control materials, it states "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." This implies that the initial "calibration" or establishment of the assay's operational parameters would have been done using these certified drug stocks, but a specific "training set" size for a machine learning model (which this device is not) is not applicable here.

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

For the calibrators and control materials (which would serve a similar function to a training set in establishing the assay's performance characteristics), the ground truth was established by:

• Certificates of Analysis for drug stocks purchased from a commercial vendor.
• Confirmation by LC/MS/MS of the concentrations of the in-house prepared calibrators and controls.

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