(177 days)
The Phencyclidine assay is used for the qualitative analysis of phencyclidine in human urine with a cutoff of 25 ng/mL for use in clinical laboratories. Measurements obtained by this device are used in the diagnosis and treatment of phencyclidine use or overdose.
The Phencyclidine assay is calibrated with phencyclidine and will detect phencyclidine and its metabolites and analogs.
The Phencyclidine assay provides only a preliminary analytical test result. A more specific alternate chemical method must be used in order to obtain a confirmed analytical 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 used.
Phencyclidine is an in vitro diagnostic assay for the qualitative analysis of Phencyclidine in human urine. The assay is a homogeneous enzyme immunoassay with a 25 ng/mL cutoff. The assay is based on competition between drug in the specimen and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for antibody binding sites. Enzyme activity decreases upon binding to the antibody, so the drug concentration in the specimen can be measured in terms of enzyme activity. Active enzyme converts NAD to NADH, resulting in an absorbance change that can be measured spectrophotometrically.
Acceptance Criteria and Device Performance Study for Phencyclidine Assay
1. Table of Acceptance Criteria and Reported Device Performance
The provided document describes a predicate device study, where the new Phencyclidine assay is compared to an existing, legally marketed device (Emit® II Phencyclidine assay) and a gold standard (GC/MS). The acceptance criteria are implicitly defined by the demonstration of "substantial equivalence" and "acceptable correlation."
| Acceptance Criteria Category | Specific Criteria (Implicit) | Reported Device Performance (Phencyclidine Assay) |
|---|---|---|
| Agreement with Predicate Device (Emit II) | "Acceptable correlation" with Emit® II Phencyclidine assay on the SYVA®-30R Analyzer. Implicitly, a high percentage of agreement. | 99% agreement with the Emit II Phencyclidine assay. One discrepant sample was positive with the Phencyclidine assay and negative with Emit II but shown to contain 14.9 ng/mL of phencyclidine by GC/MS. |
| Agreement with Gold Standard (GC/MS) | "Acceptable correlation" with GC/MS. Implicitly, a high percentage of agreement. | 93% agreement with GC/MS. |
| Qualitative Interpretation | Must provide qualitative analysis of phencyclidine in human urine at a 25 ng/mL cutoff. | Provides qualitative analysis of phencyclidine in human urine with a 25 ng/mL cutoff. |
| Precision | Demonstrates acceptable within-run and total precision across various control levels. Implicitly, low coefficient of variation (CV). | Total %CV for Verifier I: 1.42%. Total %CV for Cutoff Calibrator: 2.14%. Total %CV for Verifier II: 1.03%. Total %CV for -25% and +25% Control of Cutoff Calibrator: 2.20% and 2.07%, respectively. |
| Limit of Detection (Sensitivity) | Clinically relevant limit of detection. (No specific numerical criterion is stated, but typically an LOD below the cutoff is expected). | Limit of detection (sensitivity) is 3 ng/mL. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: The document does not explicitly state the total number of clinical specimens used for the comparative performance studies. It mentions that "The clinical specimens tested ranged from 14.9 to 78.5 ng/mL," indicating that multiple samples within this range were tested. However, a specific numerical count for the test set is not provided.
- Data Provenance: Not explicitly stated (e.g., country of origin). The studies appear to be retrospective as they involve testing clinical specimens with known drug concentrations or comparing against existing methods.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
Not applicable. This device is an in vitro diagnostic assay for drug detection, and ground truth for quantitative measurements (like drug concentration) is established through analytical gold standards (GC/MS) rather than expert interpretation of images or clinical symptoms.
4. Adjudication Method for the Test Set
Not applicable. Adjudication methods like 2+1 or 3+1 are typically used for medical image interpretation where multiple human readers assess a case and their discrepancies are resolved by an expert. For chemical assays, the "ground truth" is established by more definitive analytical methods (GC/MS in this case).
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This type of study focuses on how human reader performance changes with or without AI assistance, which is not relevant for an in vitro diagnostic assay that produces a direct analytical result.
6. Standalone (Algorithm Only) Performance
Yes, a standalone performance study was done. The document describes the performance of the Phencyclidine assay as an algorithm-only device (an in vitro diagnostic assay is inherently a standalone device). Its performance was assessed against a predicate device (Emit II) and a gold standard (GC/MS).
7. Type of Ground Truth Used
The primary ground truth used for evaluating the Phencyclidine assay was Gas Chromatography/Mass Spectrometry (GC/MS). The report states, "The Phencyclidine assay method comparison yielded acceptable correlation with GC/MS." It also mentions one sample where the discrepancy between the new assay and the predicate was resolved by GC/MS. For precision studies, specific control materials with known concentrations were used.
8. Sample Size for the Training Set
The document does not provide information on the sample size for a training set. This is typical for an enzyme immunoassay of this type, where the "training" involves optimizing the chemical reagents and assay parameters rather than machine learning on a large dataset.
9. How the Ground Truth for the Training Set Was Established
Not applicable in the context of machine learning. For this type of chemical assay, the "ground truth" for development would involve using known concentrations of phencyclidine and its metabolites to establish the assay's dose-response curve, cutoff, and to optimize its analytical performance (e.g., reagent concentrations, reaction times) to accurately detect the substance at the specified cutoff.
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