(106 days)
The Phencyclidine Enzyme Immunoassay is a homogeneous enzyme immunoassay with a 25 ng/mL cutoff. The assay is intended for use in the qualitative and semi-quantitative analyses of phencyclidine (PCP) in human urine.
The Phencyclidine Enzyme Immunoassay 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. Clinical consideration and professional judgement should be applied to any drug-ofabuse test result, particularly when preliminary positive results are used.
LZI's Phencyclidine Enzyme Immunoassay is a ready-to-use, liguid reagent, homogeneous enzyme immunoassay. The assay uses specific antibody that can detect phencyclidine in human urine with minimal cross-reactivity to various phencyclidine-related compounds and/or common drugs.
The assay is based on competition between phencyclidine labeled with enzyme glucose-6phosphate dehydrogenase (G6PDH), and free drug from the urine sample for a fixed amount of specific antibody. In the absence of free drug from the urine sample the specific antibody binds to the drug labeled with G6PDH enzyme causing a decrease in enzyme activity. The G6PDH enzyme activity is determined spectrophotometrically at 340 nm by measuring its ability to covert nicotinamide adenine dinucleotide (NAD) to NADH.
Here's an analysis of the acceptance criteria and study information for the Lin-Zhi International, Inc.' Phencyclidine Enzyme Immunoassay, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The submission generally compares the LZI device's performance to a predicate device (DRI's PCP EIA) rather than explicitly stating pre-defined acceptance criteria with numerical targets. However, based on the comparative nature of the study, the "acceptance criteria" can be inferred to be performance that is comparable to or better than the predicate.
| Feature | Predicate Device (DRI's PCP EIA) Performance (Inferred Acceptance Criteria) | LZI's Phencyclidine EIA Reported Device Performance |
|---|---|---|
| Within Run Precision (Qualitative): | Low % CV (e.g., 0.3-0.8%) | Low % CV (e.g., 0.21-0.50%) |
| Negative | Mean Rate 315, % CV 0.8 | Mean Rate 168.0, % CV 0.41 |
| 20/18 ng/mL | Mean Rate 378, % CV 0.6 | Mean Rate 238.6, % CV 0.49 |
| 25 ng/mL (Cutoff) | Mean Rate 400, % CV 0.5 | Mean Rate 264.6, % CV 0.45 |
| 35/32 ng/mL | Mean Rate 426, % CV 0.3 | Mean Rate 282.8, % CV 0.50 |
| 100 ng/mL | Mean Rate 502, % CV 0.4 | Mean Rate 341.2, % CV 0.21 |
| Within Run Precision (Semi-quantitative): | No data available | Low % CV (e.g., 1.50-1.71%) |
| 18 ng/mL | N/A | Mean Recovery 17.4, % CV 1.54 |
| 25 ng/mL | N/A | Mean Recovery 24.7, % CV 1.50 |
| 32 ng/mL | N/A | Mean Recovery 31.6, % CV 1.71 |
| Run-To-Run Precision (Qualitative): | Low % CV (e.g., 0.6-1.0%) | Low % CV (e.g., 0.23-0.54%) |
| Negative | Mean Rate 316, % CV 0.6 | Mean Rate 168.0, % CV 0.54 |
| 20/18 ng/mL | Mean Rate 380, % CV 0.9 | Mean Rate 238.8, % CV 0.23 |
| 25 ng/mL (Cutoff) | Mean Rate 400, % CV 0.6 | Mean Rate 264.6, % CV 0.30 |
| 35/32 ng/mL | Mean Rate 425, % CV 1.0 | Mean Rate 284.1, % CV 0.31 |
| 100 ng/mL | Mean Rate 501, % CV 0.9 | Mean Rate 340.1, % CV 0.32 |
| Run-To-Run Precision (Semi-quantitative): | No data available | Low % CV (e.g., 1.91-2.49%) |
| 18 ng/mL | N/A | Mean Recovery 17.1, % CV 2.49 |
| 25 ng/mL | N/A | Mean Recovery 24.3, % CV 2.26 |
| 32 ng/mL | N/A | Mean Recovery 31.4, % CV 1.91 |
| Sensitivity | 5 ng/mL | 1 ng/mL (This is better than the predicate) |
| Accuracy (vs. Commercially available EIA) | 100% Sensitivity, 100% Specificity | 100% Sensitivity, 100% Specificity (vs. DRI's PCP EIA) |
| Analytical Recovery (Qualitative) | No data available | 100% accurate of positive vs. negative tests |
| Analytical Recovery (Semi-quantitative) | No data available | Quantitates within ±10% of nominal concentration (8-80 ng/mL) |
| 96.1% recovery at 18 ng/mL | ||
| 97.8% recovery at 32 ng/mL | ||
| Specificity | Comparable to predicate device (See attached DRI PCP EIA package insert) | Comparable to the predicate device. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the sample size used for the test set. For precision studies, it lists mean rates, SD, and %CV, which implies multiple measurements were taken for each concentration level. However, the exact number of replicates or individual samples is not provided.
The data provenance is not specified (e.g., country of origin). It solely states "human urine," but for regulated submissions, more detail is typically expected. The studies appear to be retrospective, as they involve testing the new device against known concentrations or against a predicate device using existing methods.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of immunoassay (drug screening) does not typically involve human expert interpretation of results to establish ground truth in the same way as, for example, image analysis. The "ground truth" for the test set is established by:
- Known concentrations: For precision studies, specific concentrations (e.g., 18, 25, 32, 100 ng/mL phencyclidine) are prepared, representing the "ground truth."
- Referenced confirmatory methods: For accuracy studies, the predicate device and implicitly, confirmatory methods like Gas Chromatography/Mass Spectrometry (GC/MS) are used to establish ground truth.
- "Positive vs. Negative tests": For qualitative analytical recovery, the ground truth is simply whether the sample is truly positive or negative for phencyclidine.
Therefore, the concept of "experts" to establish ground truth with specific qualifications (like radiologists) does not directly apply here. The expertise is in the analytical methods and preparation of accurate controls.
4. Adjudication Method for the Test Set
Adjudication methods (like 2+1, 3+1) are typically used in studies where multiple human readers independently assess data and their discrepancies need to be resolved. This is not applicable to the analytical performance studies of this immunoassay device. The results are quantitative measurements, and accuracy is determined by comparison to known values or validated reference methods, not subjective expert consensus.
5. 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, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is an in vitro diagnostic immunoassay, not a device intended for human interpretation or AI assistance in clinical decision-making. Therefore, the concept of human readers improving with or without AI assistance is irrelevant to this submission.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the performance presented for LZI's Phencyclidine Enzyme Immunoassay is entirely standalone (algorithm/device-only performance). The assay generates results automatically based on spectrophotometric measurements and chemical reactions; there is no human in the loop for interpreting the primary analytical result provided by the device. The device provides a preliminary analytical test result that then requires professional judgment and possibly confirmatory methods.
7. The Type of Ground Truth Used (Expert Consensus, Pathology, Outcomes Data, etc.)
The ground truth used for the performance studies includes:
- Known concentrations of phencyclidine: For precision and semi-quantitative analytical recovery.
- Results from a legally marketed predicate device (DRI's PCP EIA): For accuracy and specificity comparisons. Ultimately, the predicate device would itself have been validated against gold standard chemical methods.
- Implied reference to Gas Chromatography/Mass Spectrometry (GC/MS) as the preferred confirmatory method: Although not explicitly stated as the direct ground truth for all presented studies, the "Indications for Use Statement" clearly positions it as the gold standard for confirmation.
8. The Sample Size for the Training Set
The document does not specify a "training set" in the context of device development. For an immunoassay, the development process involves reagent formulation and optimization, not machine learning model training with specific data sets. The data presented are for the analytical validation of the final device.
9. How the Ground Truth for the Training Set Was Established
As no "training set" for an algorithm or model is relevant to this immunoassay, this question is not applicable. The development of such assays relies on biochemical principles, calibration with known standards, and optimization without a "training set" in the AI sense.
N/A