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

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

The test consists of two parts; a pre-analytical hair treatment procedure (to convert the solid matrix of hair to a measurable liquid matrix) and the screening assay, the Psychemedics Microplate EIA for Cocaine. The drug is recovered from the hair using a patented method (U.S. Patent #8,084,215). The screening portion of the test system consists of (1) microplate wells coated with multiple drugs including benzoylecgonine conjugated to bovine serum albumin (BSA) (patent pending), monoclonal mouse anti-cocaine, goat anti-mouse secondary antibody conjugated to HRP (horseradish peroxidase), substrate [3, 3', 5, 5' tetramethylbenzidine (TMB)], HCl to acidify the final reaction, and wash buffer for washing the plates. Absorbance in the wells is read with a microplate reader.

Acceptance Criteria and Study for Psychemedics Microplate EIA for Cocaine in Hair

The Psychemedics Microplate EIA for Cocaine in Hair is an enzyme immunoassay (EIA) for the preliminary qualitative detection of cocaine and its metabolites in human head and body hair. The device's performance was evaluated against a predicate device (Psychemedics Cocaine Assay, K010868) and confirmed by LC/MS/MS (liquid chromatography/mass spectrometry/mass spectrometry).

1. Table of Acceptance Criteria and Reported Device Performance

The provided 510(k) summary does not explicitly state pre-defined acceptance criteria for the accuracy of the new device relative to the predicate or LC/MS/MS. However, the study aims to demonstrate "substantial equivalence" to the predicate and "substantially equivalent" results to LC/MS/MS. Based on the presented data, the implicit acceptance criteria appear to be:

• High agreement with the predicate device.
• High agreement with LC/MS/MS for confirmed samples.
• No significant impact of cosmetic treatments on negative or positive samples.
• Effective wash procedure to mitigate external contamination.
• Stability of calibrator and control solutions.
• Cross-reactivity within acceptable limits for related compounds, and minimal to no cross-reactivity or interference from other common compounds.
• Equivalent recovery to the predicate device.

Here's a summary of the reported device performance against these implicit criteria:

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

• Test Set Sample Size:

  • Agreement Testing: 425 hair samples were used for comparison between the predicate device and the new EIA.
  • LC/MS/MS Confirmation: 256 of the 425 samples were further confirmed by LC/MS/MS.
  • Cosmetic Treatment Study: 20 negative hair samples per treatment type (5 types = 100 samples), and 12 positive hair samples per treatment type (5 types = 60 samples).
  • Contamination Study: 8 hair samples per contamination method (water and saline = 16 samples).

• Data Provenance: The document does not explicitly state the country of origin of the data or whether the studies were retrospective or prospective. Given the nature of a 510(k) submission for a diagnostic device, the studies are typically conducted in a controlled laboratory environment using collected human samples, implying real-world (prospective or retrospectively collected and stored) human hair samples. The samples included both head and body hair (15.8% were body hair samples).

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

• The ground truth for the agreement and confirmation studies was established by LC/MS/MS, which is a highly specific and quantitative analytical chemical method, considered the "gold standard" for drug confirmation in forensic toxicology.
• No human "experts" in the sense of clinicians or radiologists are mentioned as establishing the ground truth for the test set results. The ground truth refers to the analytical confirmation by LC/MS/MS, performed by trained laboratory personnel.

4. Adjudication Method for the Test Set

• For the agreement testing, discrepancies between the new EIA device and the predicate RIA device (<1% of samples) were adjudicated by LC/MS/MS. The document states, "The samples were negative by LC/MS/MS, demonstrating that the EIA negative results, although discordant with the predicate, are correct." This indicates that LC/MS/MS served as the ultimate adjudicator for discordant results.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

• No. This product is an in-vitro diagnostic (IVD) assay, not an imaging device for human interpretation. Therefore, a multi-reader, multi-case comparative effectiveness study involving human readers is not applicable. The device's performance is determined by its analytical accuracy against a gold standard (LC/MS/MS), not by human interpretation improvement.

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

• Yes. The primary studies presented (Agreement Testing, LC/MS/MS Confirmation, Cosmetic Treatment, Contamination, Cross-reactivity, and Recovery) all demonstrate the standalone performance of the Psychemedics Microplate EIA for Cocaine in Hair. The output is a preliminary qualitative result (positive/negative based on cutoff), without direct "human-in-the-loop" interpretation for the initial screening result itself. The "human-in-the-loop" aspect comes in the professional judgment for clinical interpretation of any drug-of-abuse test result and the requirement for confirmation by a more specific method for positive preliminary results.

7. The Type of Ground Truth Used

• The primary ground truth used for validating the device's accuracy is LC/MS/MS (Liquid Chromatography/Mass Spectrometry/Mass Spectrometry). This is a highly sensitive and specific analytical method for identifying and quantitating substances.
• For the agreement study, the predicate device (Psychemedics Cocaine Assay, K010868) also served as an initial comparison point, though LC/MS/MS was used to resolve discrepancies.

8. The Sample Size for the Training Set

• The document does not explicitly state the sample size for a training set. For an IVD assay like this, development typically involves internal validation and optimization, but the 510(k) summary focuses on the performance studies used for regulatory submission. It is common for the public summary to detail testing data rather than development/training data for such devices.

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

• As the document does not explicitly mention a "training set" in the context of machine learning or AI models, it also does not describe how the ground truth for a training set was established. For an immunoassay, the "training" involves optimizing reagents, protocols, and cutoff values, likely guided by samples with known cocaine concentrations confirmed by methods like GC/MS or LC/MS/MS during the assay development phase.

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