(132 days)
Xenta Drug Screen Cup and Xenta Drug Screen Dipcard are lateral flow chromatographic immunoassays designed to qualitatively detect the presence of drugs and drug metabolites in human urine at the following cut-off concentrations:
| Test | Calibrator | Cut-off level |
|---|---|---|
| Marijuana (THC) | Delta-9-THC-COOH | 50 ng/mL |
| Cocaine (COC) | Benzoylecgonine | 300 ng/mL |
| Methylenedioxymethamphetamine (MDMA) | 3,4-Methylenedioxymethamphetamine | 500 ng/mL |
| Methamphetamine (MET) | D-Methamphetamine | 1000 ng/mL |
| Morphine 300 (MOP) | Morphine | 300 ng/mL |
The tests contain two formats: 1) Test Cup and 2) Test Dipcard. The tests may be configured as single drug tests or multiple drug tests in any combination of the drug analytes listed in the table above. These tests are intended for in vitro diagnostics use. They are intended for prescription use.
The assays provide only a preliminary analytical test result. Gas Chromatography/Mass spectrometry (GC/MS) is the preferred confirmatory method. Clinical consideration and professional judgment should be applied to any drug of abuse test result, particularly when preliminary positive results are indicated.
Xenta Drug Screen Cup and Xenta Drug Screen Dipcard are competitive binding, lateral flow immunochromatographic assays for the qualitative detection of Cocaine, Marijuana, Methamphetamine, Morphine, Methylenedioxymethamphetamine at or above the cut-off levels as indicated. The tests are performed without the use of an instrument.
The test cup and test dipcard formats use identical test strips made with the same chemical formulation and manufacturing procedures.
This document describes the validation of the Xenta Drug Screen Cup and Xenta Drug Screen Dipcard. The devices are lateral flow chromatographic immunoassays designed to qualitatively detect the presence of drugs and drug metabolites in human urine.
1. Table of Acceptance Criteria and Reported Device Performance & 7. Type of Ground Truth Used
The acceptance criteria for qualitative drug tests typically involve demonstrating acceptable performance around the specified cut-off concentrations. The provided document shows performance data at various concentrations relative to the cut-off, including drug-free, below cut-off, near cut-off, and above cut-off concentrations. Gas Chromatography/Mass spectrometry (GC/MS) is explicitly stated as the preferred confirmatory method and was used to confirm drug concentrations in the accuracy studies, thus serving as the ground truth.
Here's a summary of the reported device performance for each drug at the cut-off concentration from the precision study, which serves as a key measure of performance around the acceptance threshold. For precision, a high percentage of correct results (positive for samples at or above cut-off, negative for samples below cut-off) is expected.
Xenta Drug Screen Cup and Dipcard Performance at Cut-off Concentration (across 3 lots, 60 determinations per lot):
| Drug Test | Cut-off Level | Format | Lot 1 Positive (%) | Lot 1 Negative (%) | Lot 2 Positive (%) | Lot 2 Negative (%) | Lot 3 Positive (%) | Lot 3 Negative (%) |
|---|---|---|---|---|---|---|---|---|
| COC | 300 ng/mL | Single Cup | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) | 38 (63%) | 22 (37%) |
| COC | 300 ng/mL | Multi Cup | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) | 32 (53%) | 28 (47%) |
| COC | 300 ng/mL | Single Dipcard | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) |
| COC | 300 ng/mL | Multi Dipcard | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) | 32 (53%) | 28 (47%) |
| MET | 1000 ng/mL | Single Cup | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) | 38 (63%) | 22 (37%) |
| MET | 1000 ng/mL | Multi Cup | 34 (57%) | 26 (43%) | 38 (63%) | 22 (37%) | 36 (60%) | 24 (40%) |
| MET | 1000 ng/mL | Single Dipcard | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) | 34 (57%) | 26 (43%) |
| MET | 1000 ng/mL | Multi Dipcard | 38 (63%) | 22 (37%) | 36 (60%) | 24 (40%) | 36 (60%) | 24 (40%) |
| MOP300 | 300 ng/mL | Single Cup | 42 (70%) | 18 (30%) | 44 (73%) | 16 (27%) | 44 (73%) | 16 (27%) |
| MOP300 | 300 ng/mL | Multi Cup | 42 (70%) | 18 (30%) | 40 (67%) | 20 (33%) | 44 (73%) | 16 (27%) |
| MOP300 | 2000 ng/mL* | Single Dipcard | 44 (73%) | 16 (27%) | 42 (70%) | 18 (30%) | 40 (67%) | 20 (33%) |
| MOP300 | 2000 ng/mL* | Multi Dipcard | 42 (70%) | 18 (30%) | 40 (67%) | 20 (33%) | 44 (73%) | 16 (27%) |
| THC | 50 ng/mL | Single Cup | 36 (60%) | 24 (40%) | 38 (63%) | 22 (37%) | 36 (60%) | 24 (40%) |
| THC | 50 ng/mL | Multi Cup | 38 (63%) | 22 (37%) | 36 (60%) | 24 (40%) | 36 (60%) | 24 (40%) |
| THC | 50 ng/mL | Single Dipcard | 34 (57%) | 26 (43%) | 38 (63%) | 22 (37%) | 36 (60%) | 24 (40%) |
| THC | 50 ng/mL | Multi Dipcard | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) | 38 (63%) | 22 (37%) |
| MDMA | 500 ng/mL | Single Cup | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) |
| MDMA | 500 ng/mL | Multi Cup | 32 (53%) | 28 (47%) | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) |
| MDMA | 500 ng/mL | Single Dipcard | 34 (57%) | 26 (43%) | 36 (60%) | 24 (40%) | 32 (53%) | 28 (47%) |
| MDMA | 500 ng/mL | Multi Dipcard | 36 (60%) | 24 (40%) | 34 (57%) | 26 (43%) | 34 (57%) | 26 (43%) |
*Note: There seems to be a discrepancy in the MOP cut-off reported in the product description (300 ng/mL) and the concentrations used in the precision study table for the Dipcard (e.g., 2000 ng/mL for cut-off). For the purpose of reporting the precision study results, I've used the "cutoff" row as indicated in the tables, assuming that concentration represents the cut-off for the study.
2. Sample Size Used for the Test Set and Data Provenance
-
Precision Study Test Set:
- For each drug: 9 concentrations (0, -75% cut-off, -50% cut-off, -25% cut-off, cut-off, +25% cut-off, +50% cut-off, +75% cut-off, +100% cut-off).
- 3 replicates at each concentration per day for 10 non-consecutive days.
- 2 operators per location.
- One device lot per location, across 3 locations (implying 3 lots tested in total).
- Total determinations: 9 concentrations * 3 replicates * 10 days * 2 operators * 3 lots = 1620 observations for each device format (Single Cup, Multi Cup, Single Dipcard, Multi Dipcard).
- Data Provenance: The document states 3 Point-of-Care sites and refers to "clinical urine samples" in the accuracy section, suggesting the data is derived from clinical settings, likely prospective or collected for the purpose of the study. The country of origin is not explicitly mentioned for the clinical samples.
-
Accuracy Study Test Set:
- Sample Size: 80 clinical urine specimens for each drug.
- Data Provenance: "Clinical urine specimens" were used. The document does not specify the country of origin of these samples. The study involved nurses at two Point-of-Care sites, implying these were real-world clinical samples rather than simulated ones. The samples were collected and analyzed for the purpose of this study (implied prospective within the study design).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
- Precision Study: The ground truth for the precision study's spiked samples was established by the precise "spiking" of analytes at known concentrations, with confirmation by GC/MS. No human experts were judging the presence/absence of drugs for these known-concentration samples.
- Accuracy Study: For the 80 clinical urine specimens "analyzed by GC/MS," GC/MS itself served as the gold standard ground truth. While GC/MS is operated by trained laboratory personnel, the document does not specify the number of "experts" (e.g., medical toxicologists, clinical chemists) who reviewed or confirmed the GC/MS results, nor their specific qualifications. It simply states the samples were "analyzed by GC/MS".
4. Adjudication Method for the Test Set
- Precision Study: For the spiked samples, results (positive/negative) were compared against the known spiked concentrations relative to the cut-off. Discordant results are not explicitly adjudicated by a separate panel but are inherent in the calculation of positive/negative agreement at various concentrations.
- Accuracy Study: The ground truth was established by GC/MS. The document then presents "Analysis of Discordant Results" where the test result is compared against the GC/MS confirmed drug concentration in urine. This implies a direct comparison rather than a separate adjudication panel for discrepant cases. For example, for the Single Drug Test Cup, a MET sample with GC/MS concentration of 867 ng/mL (below cut-off of 1000 ng/mL) was classified as "Positive" by the Xenta device. Similarly, an MDMA sample with GC/MS concentration of 715 ng/mL (above cut-off of 500 ng/mL) was classified as "Negative" by the device. These are reported as discordant results without further human adjudication in the document.
5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. The Xenta Drug Screen Cup and Dipcard are point-of-care immunoassay devices, which are typically read visually or by simple optical readers, not by complex AI algorithms that assist human readers in interpretation. The performance data presented is for the device's standalone accuracy against a gold standard (GC/MS).
6. If a Standalone (i.e. algorithm only without human-in-the loop performance) Was Done
Yes, the studies described (Precision and Accuracy) represent the standalone performance of the Xenta Drug Screen Cup and Dipcard. These devices are designed to provide a direct positive/negative result without human interpretation beyond visually inspecting the test line. Therefore, the reported accuracy and precision data reflect the algorithm-only performance, as applied to these types of lateral flow immunoassays.
8. The Sample Size for the Training Set
The document does not provide details on a specific "training set" in the context of an algorithmic or AI device. Since the device is a lateral flow immunoassay, its "training" would typically involve optimization of chemical reagents and manufacturing processes during its development, rather than an algorithmic training phase with a distinct dataset. The performance data presented here are for validation testing.
9. How the Ground Truth for the Training Set Was Established
As indicated in point 8, a traditional "training set" with established ground truth, as would be used for AI/ML model development, is not applicable to these types of immunoassay devices. The inherent "ground truth" during device development would be established through careful analytical studies using known concentrations of analytes and cross-reactants to optimize the device's sensitivity and specificity to meet the specified cut-offs.
§ 862.3650 Opiate test system.
(a)
Identification. An opiate test system is a device intended to measure any of the addictive narcotic pain-relieving opiate drugs in blood, serum, urine, gastric contents, and saliva. An opiate is any natural or synthetic drug that has morphine-like pharmocological actions. The opiates include drugs such as morphine, morphine glucoronide, heroin, codeine, nalorphine, and meperedine. Measurements obtained by this device are used in the diagnosis and treatment of opiate use or overdose and in monitoring the levels of opiate administration to ensure appropriate therapy.(b)
Classification. Class II (special controls). An opiate 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).