(64 days)
The Emit® II Plus Phencyclidine Assay is a homogeneous enzyme immunoassay with a 25 ng/mL cutoff (SAMHSA initial test cutoff level). The assay is intended for use in the qualitative and semiquantitative analyses of phencyclidine in human urine. Emit® II Plus assays are designed for use with a number of chemistry analyzers.
The Emit® II Plus Phencyclidine Assay provides only a preliminary analytical test result. A more specific alternative chemical method must be used to obtain a confirmed analytical result. Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method. Other chemical confirmation methods are available. Clinical consideration and professional judgment should be applied to any drug-of-abuse test result, particularly when preliminary positive results are used.
The Emit® II Plus Phencyclidine Assay is a homogenous enzyme assay intended for use in qualititative and semiquantitative analysis of phencyclidine in human urine. The Emit® II Plus Phencyclidine Assay and has been found to be equivalent to the predicate device: Emit® II Phencyclidine Assay with regard to intended use, assay sample, and overall performance characteristics.
Here's an analysis of the provided text regarding the Emit® II Plus Phencyclidine Assay, focusing on acceptance criteria and the supporting study:
The provided document describes a 510(k) submission for the Emit® II Plus Phencyclidine Assay, establishing its substantial equivalence to a predicate device (Emit® II Phencyclidine Assay). The studies presented are primarily for demonstrating this equivalence.
Acceptance Criteria and Reported Device Performance
The document describes several performance characteristics rather than explicit acceptance criteria with pre-defined thresholds for each. However, we can infer the implied acceptance criteria from the reported results and the comparison to the predicate device.
| Performance Characteristic | Stated Acceptance Criteria (Inferred) | Reported Device Performance (Emit® II Plus) |
|---|---|---|
| Qualitative Analysis | Excellent correlation to the predicate device (Emit® II Phencyclidine Assay). | 99% agreement with the predicate device using a 25 ng/mL cutoff. One discordant sample (15 ng/mL PCP by GC/MS) was positive by Emit® II Plus and negative by Emit® II. |
| Spiked Sample Recovery (Qualitative) | Consistently distinguish negative vs. positive: 25% of cutoff should be positive. | Spiked levels 25% of 25 ng/mL cutoff (31.25 - 300 ng/mL) were consistently distinguished as positive. |
| Spiked Sample Recovery (Semiquantitative) | Quantitated results within 10% of nominal concentration for a specified range. | Quantitated within 10% of nominal concentration between 8.0 ng/mL and 90 ng/mL. |
| Precision (Qualitative - Within-run) | Acceptable within-run precision for controls and cutoff (rates). | %CV for controls and cutoff (rates) at 0.5%. |
| Precision (Qualitative - Total) | Acceptable total precision for controls and cutoff (rates). | %CVs for controls and cutoff (rates) ranged from 0.5 to 0.6%. |
| Precision (Semiquantitative - Within-run) | Acceptable within-run precision for controls and cutoff (concentrations). | %CV for controls and cutoff (concentrations) ranged from 1.79 to 2.44%. |
| Precision (Semiquantitative - Total) | Acceptable total precision for controls and cutoff (concentrations). | %CV ranged from 2.18 to 2.60%. |
| Correlation with GC/MS | Good relationship between semiquantitative analyses and GC/MS values. (This is a more general statement of acceptance rather than a specific numeric criterion). | Demonstrated a "good relationship" between semiquantitative analyses and GC/MS values for all positive samples and a portion of negative samples (n=20). |
Study Details
This document describes a performance study conducted to demonstrate substantial equivalence, not a standalone clinical validation study in the traditional sense, especially concerning an AI/ML device.
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Sample size used for the test set and the data provenance:
- Test Set Sample Size: 100 specimens for comparative analysis (49 positive, 50 negative by both Emit® II Plus and Emit® II).
- Data Provenance: Not explicitly stated (e.g., country of origin, demographics). The study appears to be laboratory-based internal testing, likely retrospective using collected urine samples. It is implied the samples are human urine.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- This is not applicable in the context of this device. The ground truth for drug-of-abuse testing is established by confirmatory methods (like GC/MS) and reference assays (the predicate Emit® II assay), not by human expert opinion.
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Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- Not applicable. When there was a discrepancy between the Emit® II Plus and the predicate Emit® II assay, Gas Chromatography/Mass Spectrometry (GC/MS) was used as the confirmatory (adjudication) method. For example, one discordant sample was confirmed by GC/MS to have 15 ng/mL of PCP.
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If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- No. This is not an AI/ML device, nor does it involve human readers interpreting images or data. It is an in vitro diagnostic (IVD) assay that provides quantitative and qualitative results directly.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, in the sense that it's an automated assay. The Emit® II Plus Phencyclidine Assay is a homogeneous enzyme immunoassay designed for use with chemistry analyzers, meaning it provides results without direct human interpretation of a visual output where human error in reading is a factor. The "performance" refers to the assay's output itself, which is then interpreted by a human user (e.g., laboratory technician, physician) in the context of the patient. However, it's not "algorithm-only" in the AI/ML sense. It's a chemical assay.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- For positive confirmation: Gas Chromatography/Mass Spectrometry (GC/MS) was used as the reference (confirmatory) method.
- For comparison/equivalence: The predicate device, Emit® II Phencyclidine Assay, served as the comparative method.
- For "known" samples: Spiked samples with known concentrations of phencyclidine were used.
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The sample size for the training set:
- This information is not provided as this is not an AI/ML device that undergoes a 'training' phase in the conventional sense. The development of such an assay involves reagent formulation and optimization, not machine learning model training on a dataset.
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How the ground truth for the training set was established:
- Not applicable. As stated above, this is not an AI/ML device. The "ground truth" during development would be established through careful analytical chemistry and formulation to ensure the assay reagents react as expected with known concentrations of phencyclidine and its metabolites.
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