(204 days)
The Omega Laboratories Hair Drug Screening Assay for Cocaine and Cocaine Metabolites (Cocaine) is an in vitro diagnostic test that is intended for the qualitative detection of Cocaine at or above 500 pg/mg in human head and body hair. To confirm a screen positive result, a more specific alternate chemical method, such as Gas Chromatography/Mass Spectrometry (GC/MS) operating in the selected ion monitoring (SIM) mode is the preferred method with deuterated internal standards. Professional judgment should be applied to any drug of abuse test result, particularly when presumptive positive results are obtained. This test is intended exclusively for single laboratory use only and is not intended for sale to anyone.
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Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:
Acceptance Criteria and Device Performance for Omega Hair Drug Screening Assay for Cocaine and Cocaine Metabolites
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for substantial equivalence are demonstrated through various performance studies showing the device's agreement with a reference method (GC/MS) and its precision. Specific quantitative acceptance criteria for parameters like sensitivity, specificity, and accuracy are not explicitly stated with numerical targets, but the overall conclusion is based on "substantial agreement" and "acceptability."
| Acceptance Criteria | Reported Device Performance (Omega Assay vs. GC/MS or internal controls) |
|---|---|
| Precision (Intra-assay) | 11/11 correct results for all tested concentrations (negative, -75%, -50%, -25% below cutoff, and +25%, +50%, +75%, +100% above cutoff). |
| Precision (Inter-assay) | 220/220 correct results for all tested concentrations (negative, -75%, -50%, -25% below cutoff, and +25%, +50%, +75%, +100% above cutoff) over 20 non-consecutive runs. (Precision deemed acceptable if %CV 750 pg/mg) correctly identified as Positive by ELISA. |
- 31 GC/MS Negative (250-499 pg/mg) identified as Positive by ELISA (discordant).
(Specific sensitivity/specificity/accuracy metrics are not provided in percentage form, but raw counts are given.) |
| Cross-Reactivity | Structurally similar compounds (Benzoylecgonine isopropyl ester, Cocaethylene, Cocaine, Benzoylecgonine, Meta-Hydroxybenzoylecgonine, Ecgonine, Norbenzoylecgonine, Norcocaine, Norcocaethylene, Ecgonine methyl ester, Anhydroecgonine methyl ester) demonstrated varying degrees of cross-reactivity. The report notes that these contributed to a positive ELISA result, but GC/MS confirmation would differentiate them. |
| Interfering Compounds | Structurally unrelated compounds did not interfere with the assay. Only structurally cross-reactive compounds produced a positive response. No expected positive samples produced a negative result. |
| Calibrator and Control Validation | Successfully demonstrated validation and stability of in-house prepared calibrator and control solutions, traceable to NIST standards. |
| Stability (Long-term storage) | Mean variance in concentration of combined cocaine + metabolites was -23% over ~2 years. Largest decrease was -46%, largest increase was 17%. General trend of decreasing cocaine and increasing benzoylecgonine noted. |
| Shipping Effects | No adverse effect on head hair samples and no discordant results (pre- and post-shipping) when exposed to extreme temperatures and humidity. Average percent change in positive cocaine GC/MS results was +5% for all locations combined. |
| Cosmetic Treatment Effects | Device is not an exception to the phenomenon that cosmetic treatments can reduce drug amounts. Four initially positive ELISA assays reported negative after treatment (bleach or perm). |
| Environmental Contamination | Acknowledged that preliminary positive results could be due to environmental contamination, emphasizing the need for GC/MS confirmation to distinguish true positives. |
2. Sample Sizes Used for the Test Set and Data Provenance
- Test Set Sample Size: For the agreement study, 424 hair samples were used.
- Data Provenance: The origin of the data (e.g., country of origin, retrospective or prospective) is not specified in the provided text. It only states that testing was performed on "body and head hair samples from different ages, gender, ethnicities and hair color."
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
- Number of Experts: Not explicitly stated.
- Qualifications of Experts: The ground truth for the agreement study was established using Gas Chromatography/Mass Spectrometry (GC/MS), which is a "more specific alternate chemical method" and "the preferred method with deuterated internal standards." This implies analysis by qualified laboratory personnel, but their specific number or qualifications (e.g., experience level) are not provided.
4. Adjudication Method for the Test Set
- Adjudication Method: The text states, "Each specimen was divided into two aliquots and one was used for screening and the other for GC/MS confirmation." This indicates that any discrepancies between the ELISA screening and the GC/MS confirmation would be resolved by the GC/MS result, as it is considered the "reference method" and "preferred method." There is no explicit mention of a multi-reader adjudication panel (like 2+1 or 3+1). The GC/MS acts as the definitive adjudicator.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- Was it done?: No. This study evaluates an in vitro diagnostic test (ELISA assay), not a device that assists human readers in interpreting images or other data. Therefore, a multi-reader multi-case (MRMC) comparative effectiveness study with human readers assisting with AI vs. without AI assistance is not applicable to this type of device and was not performed.
6. Standalone Performance Study
- Was it done?: Yes. The document presents standalone performance data for the ELISA assay against the GC/MS reference method. The "Agreement" section (Table 4a and 4b) directly compares the results of the Omega Laboratories Hair Drug Screening Assay (algorithm only, without human intervention in the interpretation of the assay result itself) to the GC/MS ground truth. The precision studies also represent standalone performance.
7. Type of Ground Truth Used
- Type of Ground Truth: The primary ground truth used for the agreement study and for confirming screen positive results is Gas Chromatography/Mass Spectrometry (GC/MS) results, specifically mentioned as operating in the selected ion monitoring (SIM) mode with deuterated internal standards. This is a highly accurate and accepted analytical chemistry method for drug detection and quantification.
8. Sample Size for the Training Set
- Training Set Sample Size: The document describes performance studies, but it does not provide information on a specific training set size for the development of the ELISA assay. This assay likely relies on established biochemical principles and reagent formulation rather than machine learning algorithms that typically require a distinct training set. The various "performance studies" described are for validation, not typically for training.
9. How the Ground Truth for the Training Set Was Established
- Ground Truth for Training Set: As no explicit training set is described for this type of immunoassay, the concept of establishing ground truth for a training set in the context of an AI/ML algorithm is not applicable. The assay's development would involve optimizing antibody specificity and binding characteristics against known concentrations of cocaine and its metabolites, with the performance ultimately validated against a gold standard like GC/MS.
§ 862.3250 Cocaine and cocaine metabolite test system.
(a)
Identification. A cocaine and cocaine metabolite test system is a device intended to measure cocaine and a cocaine metabolite (benzoylecgonine) in serum, plasma, and urine. Measurements obtained by this device are used in the diagnosis and treatment of cocaine use or overdose.(b)
Classification. Class II (special controls). A cocaine and cocaine metabolite test system is not exempt if it is intended for any use other than employment or insurance testing or is intended for Federal drug testing programs. The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 862.9, provided the test system is intended for employment and insurance testing and includes a statement in the labeling that the device is intended solely for use in employment and insurance testing, and does not include devices intended for Federal drug testing programs (e.g., programs run by the Substance Abuse and Mental Health Services Administration (SAMHSA), the Department of Transportation (DOT), and the U.S. military).