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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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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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