(87 days)
Wondfo Amphetamine Urine Test (AMP 300) and Wondfo Methamphetamine Urine Test (MET 500) are intended for the qualitative determination of d-Amphetamine and D(+)-Methamphetamine (target analyte) at the specific cut-off concentration in human urine. This product is only intended for prescription use and is not intended for point-of-care use. For in vitro diagnostic use only.
Wondfo Amphetamine Urine Test (AMP 300):
Wondfo Amphetamine Urine Test (AMP 300) is an immunochromatographic assay for the qualitative determination of d-Amphetamine in human urine at a cutoff concentration of 300 ng/mL. The test is available in a Dip Card format and a Cup format. This product is only intended for prescription use and is not intended for point-of-care use. For in vitro diagnostic use only.
The test provides only preliminary test results. A more specific alternative chemical method must be used in order to obtain a confirmed analytical result. GC/MS is the preferred confirmatory method. Clinical consideration and professional judgment should be exercised with any drug of abuse test result, particularly when the preliminary result is positive.
Wondfo Methamphetamine Urine Test (MET 500):
Wondfo Methamphetamine Urine Test (MET 500) is an immunochromatographic assay for the qualitative determination of D(+)-Methamphetamine in human urine at a cutoff concentration of 500 ng/mL. The test is available in a Dip Card format and a Cup format. This product is only intended for prescription use and is not intended for point-of-care use. For in vitro diagnostic use only.
The test provides only preliminary test results. A more specific alternative chemical method must be used in order to obtain a confirmed analytical result. GC/MS is the preferred confirmatory method. Clinical consideration and professional judgment should be exercised with any drug of abuse test result, particularly when the preliminary result is positive.
Assay Principle: Immunochromatograph assay for Amphetamine and Methamphetamine Urine Test using a lateral flow, one step system for the qualitative detection of d-Amphetamine and D(+)-Methamphetamine (target analyte) in human urine. Each assay uses a monoclonal antibody-dye conjugate from mouse against drug with gold chloride and fixed drug-protein conjugate and anti-mouse IgG polyclonal antibody in membrane.
Wondfo Amphetamine Urine Test (AMP 300) and Wondfo Methamphetamine Urine Test (MET 500) are a one-step lateral flow immunoassay containing a conjugate pad with colloidal gold with anti-drug antibodies, a nitrocellulose membrane, with a test line (T) and a control line (C). The T line is coated with drug-protein conjugate and the C line is coated with goat anti-mouse IgG polyclonal antibodies. The test is a competitive binding immunoassay in which drugs in a urine sample compete with immobilized drug conjugate for limited labeled antibody binding sites. When a sufficient amount of sample is applied, the sample migrates through the test device by capillary action.
If the concentration of drug is below the cutoff level, the anti-drug antibodies in the colloidal gold particles will bind to the drug antigens coated in the test zone producing a band which indicates a negative result. If the drug concentration is at the cutoff level or higher no band will form in the test zone (test line T) indicating a preliminary positive. A band should form in the control region reqardless of the presence of drug or metabolite in the sample.
1. Table of Acceptance Criteria and Reported Device Performance:
The document describes performance in terms of Precision and Comparison Studies (agreement with GC/MS). There aren't explicitly stated "acceptance criteria" in a numerical threshold format (e.g., "sensitivity must be >95%"). However, the precision study demonstrates performance at various percentages of the cutoff, which implies an expectation for accurate detection around these critical thresholds. The comparison study directly compares the device's qualitative results to a gold standard (GC/MS).
Here's a table summarizing the reported device performance, with implied acceptance from the provided data:
Wondfo Amphetamine Urine Test (AMP 300) - Cup Format
| Performance Characteristic | Reported Device Performance (Example for 3 lots) | Implied Acceptance Criteria (based on data presentation) |
|---|---|---|
| Precision | ||
| -100% cutoff | 50-/0+ (All negative) | Consistent negative results well below cutoff |
| -75% cutoff | 50-/0+ (All negative) | Consistent negative results below cutoff |
| -50% cutoff | 50-/0+ (All negative) | Consistent negative results below cutoff |
| -25% Cut off | 50-/0+ (All negative) | Consistent negative results approaching cutoff |
| +25% cut off | 47+/3-, 45+/5- (Mix of positive/negative) | Majority positive, tolerating some false negatives |
| +50% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| +75% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| +100% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| Comparison Study (vs GC/MS) | ||
| Drug-free (Negatives) | All viewers: 10 Negative, 0 Positive | 100% agreement with GC/MS for drug-free samples |
| Low Negative ( +50%) | All viewers: 0 Negative, 11 Positive | 100% agreement with GC/MS for high positive samples |
Wondfo Methamphetamine Urine Test (MET 500) - Cup Format
| Performance Characteristic | Reported Device Performance (Example for 3 lots) | Implied Acceptance Criteria (based on data presentation) |
|---|---|---|
| Precision | ||
| -100% cutoff | 50-/0+ (All negative) | Consistent negative results well below cutoff |
| -75% cutoff | 50-/0+ (All negative) | Consistent negative results below cutoff |
| -50% cutoff | 50-/0+ (All negative) | Consistent negative results below cutoff |
| -25% Cut off | 50-/0+ (All negative) | Consistent negative results approaching cutoff |
| +25% cut off | 45+/5-, 46+/4- (Mix of positive/negative) | Majority positive, tolerating some false negatives |
| +50% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| +75% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| +100% cut off | 50+/0- (All positive) | Consistent positive results well above cutoff |
| Comparison Study (vs GC/MS) | ||
| Drug-free (Negatives) | All viewers: 10 Negative, 0 Positive | 100% agreement with GC/MS for drug-free samples |
| Low Negative ( +50%) | All viewers: 0 Negative, 20 Positive | 100% agreement with GC/MS for high positive samples |
(Note: Dip Card format shows very similar performance to Cup Format in the provided data)
2. Sample Size and Data Provenance for Test Set:
- Sample Size:
- Precision Studies: For each drug (AMP 300 and MET 500) and format (Cup, Dip Card), and for each of 3 lots, 50 tests were performed at each of 8 concentrations (a total of 400 tests per lot per drug/format, or 1200 tests per drug/format across 3 lots).
- Comparison Studies (with GC/MS): For each drug (AMP 300 and MET 500) and format (Cup, Dip Card), 80 unaltered clinical urine samples were used (40 negative and 40 positive based on GC/MS). Each sample was tested by 3 laboratory assistants. So, 80 samples * 3 viewers = 240 results per drug/format for the comparison.
- Data Provenance: "Unaltered clinical samples" imply the data is from real patient samples. The document does not specify the country of origin but was submitted by a company in Guangzhou, P.R. China, with a contact in Gaithersburg, MD, USA. The study was performed "in-house." The nature of the study (using clinical samples, compared to a gold standard) suggests it is retrospective, as the GC/MS results would have been established prior to or concurrently with the device testing for comparison.
3. Number of Experts and Qualifications for Ground Truth (Test Set):
- Number of Experts: For the comparison studies, the "Wondfo Result" (the classification by the device) was read by 3 laboratory assistants. Their qualifications are stated as having "relevant experience reading the instructions for use."
- Ground Truth Qualification: The primary ground truth for the comparison study was established by GC/MS (Gas Chromatography/Mass Spectrometry). This is explicitly stated as "GC/MS results" and "GC/MS is the preferred confirmatory method." GC/MS is a highly accurate and accepted gold standard for drug detection and quantification in urine.
4. Adjudication Method for the Test Set:
- The document implies no adjudication was performed among the "3 laboratory assistants" for the comparison study. Each viewer's results are presented separately. The "Viewer Result" column reflects individual interpretations. The final comparison is made against the GC/MS result for each sample, indicating a direct comparison rather than an adjudicated consensus among the viewers of the Wondfo device.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No, a typical MRMC comparative effectiveness study was not done in the sense of comparing human readers with AI assistance versus without AI assistance to measure improvement. This document describes the performance of a standalone diagnostic device (an immunoassay), not an AI algorithm assisting human readers.
- The "Wondfo Result" is the interpretation of the immunoassay itself, not an AI output. The "human readers" in this context (the 3 laboratory assistants) are simply interpreting the visual result of the Wondfo test, and their individual performance (agreement with GC/MS) is shown.
6. Standalone Performance Study:
- Yes, a standalone performance study was done. The entire "Performance Characteristics" section details the standalone performance of the Wondfo Amphetamine Urine Test and Wondfo Methamphetamine Urine Test.
- Precision studies evaluate the device's consistency and reliability at different concentrations.
- Comparison studies directly compare the device's qualitative results to the GC/MS ground truth without human intervention in the interpretation of the GC/MS or the Wondfo result (other than the laboratory assistants visually reading the test line). The results presented are essentially the device's output compared to the reference. This is a standalone evaluation of the device's diagnostic accuracy.
7. Type of Ground Truth Used:
- GC/MS (Gas Chromatography/Mass Spectrometry) was used as the ground truth for the comparison studies. This is a highly specific and sensitive analytical method considered the gold standard for confirming drug presence and concentration in biological samples.
8. Sample Size for the Training Set:
- This document describes the performance of an immunoassay device, which is based on pre-set chemical reactions and antibodies, not a machine learning model that requires a "training set" in the computational sense. Therefore, the concept of a training set sample size is not applicable to this device. The device itself is "trained" by its manufacturing process to react to specific analytes at given concentrations.
9. How Ground Truth for the Training Set Was Established:
- As stated above, this is not applicable because the device is a chemical immunoassay, not an AI/machine learning algorithm requiring a computational training set with associated ground truth. The "ground truth" during the development and manufacturing of such a device would relate to the chemical properties of the analytes (d-Amphetamine and D(+)-Methamphetamine) and the specificity and sensitivity of the antibodies and reagents used.
§ 862.3100 Amphetamine test system.
(a)
Identification. An amphetamine test system is a device intended to measure amphetamine, a central nervous system stimulating drug, in plasma and urine. Measurements obtained by this device are used in the diagnosis and treatment of amphetamine use or overdose and in monitoring levels of amphetamine to ensure appropriate therapy.(b)
Classification. Class II (special controls). An amphetamine 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).