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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 Barbiturates (BAR) Benzodiazepines (BZO) Amphetamine (AMP) Methadone (MTD) Oxycodone (OXY) Phencyclidine (PCP)

• Calibrator Secobarbital Oxazepam D-Amphetamine Methadone Oxycodone Phencyclidine
  Cut-off level 300 ng/mL 300 ng/mL 1000 ng/mL 300 ng/mL 100 ng/mL 25 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 Barbiturate, Benzodiazepine, Amphetamine, Methadone, Oxycodone, Phencyclidine 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.

The provided document describes the performance of the Xenta Drug Screen Cup and Xenta Drug Screen Dipcard for detecting various drugs in human urine. The study evaluates cross-reactivity, interference, effect of pH and specific gravity, precision, and accuracy.

Here's an breakdown of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria (Implicit) and Reported Device Performance

The document does not explicitly state "acceptance criteria" but rather presents a rigorous set of performance data that would generally be used to support claims of substantial equivalence. For immunoassays of this type, key performance indicators are typically precision (agreement at different concentrations, especially near the cutoff) and accuracy (agreement with a gold-standard confirmatory method like GC/MS).

Implicit Acceptance Criteria (based on common standards for such devices):

• Precision: High percentage of agreement (positive/negative results) for samples spiked at various concentrations, especially those near the cutoff (e.g., -25% and +25% of cutoff). For negative and very high positive concentrations, 100% agreement would generally be expected.
• Accuracy: High concordance with a confirmatory method (GC/MS) for clinical samples, particularly for drug-free, high positive, and discordant samples.
• Specificity (Cross-reactivity): Low or no cross-reactivity with structurally similar compounds and other common substances, or clearly defined cross-reactivity profiles.
• Robustness (Interference, pH, Specific Gravity): The device's performance should not be significantly affected by common interfering substances, varying urine pH, or specific gravity within physiological and expected ranges.

Reported Device Performance:

The document provides extensive data demonstrating the device's performance across these parameters. For brevity, here's a summary derived from the tables provided in section 8:

Note: Agreement is nearly 100% for samples significantly below (-75%, -50% cutoff) and significantly above (+50%, +75%, +100% cutoff) the cutoff. |
| Accuracy (Concordance with GC/MS) | For all drugs (AMP, BAR, BZO, MTD, OXY, PCP) and both device formats (Single/Multi Drug Test Cup and Dipcard), the device consistently showed:

• 0 false positives in drug-free samples.
• 0 false positives in samples less than half the cutoff.
• Very few false positives (0-1) and some false negatives (4-8) in the "Near Cutoff Negative" (between 50% below cutoff and cutoff concentration) category.
• Very few false positives (0) and some false negatives/positives (range varies, but generally consistent with expected +/- 25% cutoff performance) in the "Near Cutoff Positive" (between cutoff and 50% above cutoff concentration) category.
• 0 false negatives in "High Positive" samples (greater than 50% above the cutoff).
  Specific discordant results are minimal and generally at concentrations very close to the cutoff.
  In total, for each drug, 80 clinical samples were tested, with very high overall agreement for clearly negative or clearly positive samples. |
  | Cross-reactivity | Detailed tables show the lowest concentration of various related compounds that produced a positive result. Percent cross-reactivity is calculated. E.g., L-Amphetamine: 2%, MDA: 50%, Hydrocodone: 3.3%. This is a comprehensive evaluation common for immunoassays. |
  | Interference | "None of the compounds listed below were shown to interfere." (List includes numerous common medications and physiological substances at 100 µg/mL). |
  | Effect of pH | "The results demonstrate that varying ranges of pH do not interfere with the performance of the test." (Tested pH range 3-9). |
  | Effect of Specific Gravity | "The results demonstrate that varying ranges of urinary specific gravity do not affect the test result." (Tested SG 1.002 to 1.040). |
  | Stability of Test Line | "The results show that the color T line... are stable from 3 to 50 minutes." (Suggested read time: 5 to 30 minutes). |

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

• Precision Test Set Sample Size:
  • For each drug, for both single and multi-drug formats, and for both Test Cup and Test Dipcard:
    • 9 concentrations (0, -75%, -50%, -25%, Cutoff, +25%, +50%, +75%, +100% of cutoff).
    • 60 determinations per lot for each concentration (this is derived from 3 aliquots x 3 runs/day x 10 days x 2 operators/device type at each of the 3 sites, meaning 60 samples per lot, per concentration for each device type).
    • Tested with 3 lots.
    • Total precision observations for one drug and one device format (e.g., AMP on Single Test Cup) = 9 concentrations x 60 determinations/lot x 3 lots = 1620 observations.
    • Total observations for all 6 drugs and 2 device types (Single Test Cup, Multi Test Cup, Single Test Dipcard, Multi Test Dipcard) multiplied by 1620 observations per format.
• Accuracy Test Set Sample Size:
  • 80 clinical urine samples per drug (AMP, BAR, BZO, MTD, OXY, PCP) for each of the four device variants (Single Drug Test Cup, Multi Drug Test Cup, Single Drug Test Dipcard, Multi Drug Test Dipcard).
  • Total accuracy samples = 80 samples/drug x 6 drugs = 480 clinical samples (with GC/MS confirmation). These 480 samples are then tested across the 4 device variants.
• Data Provenance:
  • Clinical Urine Samples: "80 clinical urine samples collected all from sample place several hospitals and drug relief reformatory."
  • Retrospective/Prospective: The description does not explicitly state retrospective or prospective collection for the clinical samples. However, given they were "collected all from sample place," it implies they were likely existing samples (retrospective) or collected for the specific purpose of the study (prospective), but the exact method isn't specified. The emphasis on blind labeling and randomization for testing suggests a controlled prospective-like application in the study even if samples were retrospectively sourced.
  • Country of Origin: Not explicitly stated for specific samples, but the submitting company is "Xenta Biomedical Science Co., Ltd." located in Guangzhou, China.

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

• The ground truth for the clinical accuracy test set was established by Gas Chromatography/Mass spectrometry (GC/MS). GC/MS is considered the "preferred confirmatory method" and the gold standard for drug detection in urine.
• No human "experts" (e.g., radiologists) were used to establish the ground truth in this context; instead, a highly accurate analytical laboratory method (GC/MS) served as the gold standard. Therefore, the concept of "qualifications of those experts" does not directly apply in the way it would for image-based diagnostic devices. The expertise lies in the laboratory personnel performing and interpreting the GC/MS analysis.

4. Adjudication Method for the Test Set

• GC/MS was used as the confirmatory method to adjudicate the results of the rapid tests.
• For the precision study, samples were "blindly labeled by a nonparticipant" and "randomized prior to testing," indicating a blind comparison against the known spiked concentrations.
• For the accuracy study, clinical samples were also "blindly labeled by a nonparticipant" and "randomized prior to testing" against the GC/MS confirmed results.
• There's no mention of a traditional group adjudication method (e.g., 2+1, 3+1) involving multiple human readers of the rapid test, as the rapid test is interpreted visually by a single operator. Discordant results were analyzed by comparing the device result directly against the GC/MS result and the drug concentration.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, and the effect size of human readers improve with AI vs without AI assistance

• No, an MRMC comparative effectiveness study was not performed, nor would it be applicable for this type of device.
• This device is a qualitative lateral flow immunoassay for drug detection in urine, designed for visual interpretation. It is not an AI-assisted diagnostic imaging device for human interpretation like those typically evaluated in MRMC studies. Therefore, there's no AI component or human reader improvement analysis.

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

• Yes, in essence. The device itself is a "standalone" test in the sense that its performance (how accurately it detects drugs based on chemical reactions) is tested directly against gold standard methods (GC/MS) or known spiked concentrations.
• The interpretation step is visual, performed by a human operator, but the core performance data (cross-reactivity, precision, accuracy) reflect the inherent capability of the immunoassay itself to produce a detectable signal at certain concentrations. The studies described are primarily focused on this standalone performance of the test strip.

7. The Type of Ground Truth Used

• Laboratory Confirmatory Method (GC/MS): This was the primary gold standard ground truth for the clinical accuracy studies.
• Known Spiked Concentrations: For the precision studies, the ground truth was established by spiking drug-free urine with precisely measured concentrations of analytes, confirmed by GC/MS. This allows for a very controlled evaluation of the device's consistency and ability to detect at specific thresholds.

8. The Sample Size for the Training Set

• The document describes performance studies for the device, implying a final validation of a developed product. It does not mention a "training set" in the context of an algorithm or machine learning model.
• For a traditional immunoassay, there isn't a "training set" in the computational sense. The "training" for such a device involves the biochemical development and optimization of the reagents and test strip design. The provided data are for verification and validation of the final product.

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

• As there is no "training set" in the context of an AI/machine learning algorithm, this question is not applicable. The development of an immunoassay involves optimizing antibody-antigen reactions and signal generation, which is a biochemical engineering process, not a data-driven model training process.

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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:

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):

*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.

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