(187 days)
The Diagnostic Hybrids, Inc. device, D3 Duet DFA Influenza A/Respiratory Virus Screening Kit, is intended for the qualitative detection and identification of influenza A, while screening for influenza B virus, respiratory syncytial virus, adenovirus, and parainfluenza virus types 1, 2 and 3 viral antigens, in nasal and nasopharyngeal swabs and aspirates or in cell culture. The assay detects viral antigens by immunofluorescence using monoclonal antibodies (MAbs), from patients with signs and symptoms of respiratory infection.
It is recommended that specimens found to be negative after examination of the direct specimen result be confirmed by cell culture. Negative results do not preclude influenza virus infection and should not be used as the sole basis for diagnosis, treatment or other management decisions.
Performance characteristics for influenza A virus detection and identification were established when influenza A H3N2 and influenza A H1N1 were the predominant influenza A strains circulating in the United States. When other Influenza A viruses are emerging, performance characteristics may vary. If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to a state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.
The Diagnostic Hybrids, Inc. device, D Duet DFA Influenza A/Respiratory Virus Screening Kit, uses a blend of viral antigen-specific murine MAbs. MAbs for influenza A virus are directly labeled with R-phycoerythrin (R-PE) for the rapid detection and identification of influenza A virus. MAbs for influenza B virus, respiratory syncytial virus, adenovirus, and parainfluenza virus types 1, 2, and 3 are directly labeled with fluorescein isothiocyanate (FITC), for rapid detection of these agents.
Kit components:
- D3 Duet DFA Influenza A/Respiratory Virus Screening Reagent Rphycoerythrin-labeled murine MAbs directed against influenza A virus and a mixture of fluorescein-labeled murine MAbs directed against influenza B. respiratory syncytial virus, adenovirus, and parainfluenza virus types 1, 2, and 3. The buffered, stabilized, aqueous solution also contains Evans Blue as a counterstain and 0.1% sodium azide as preservative.
- Normal Mouse Gamma Globulin DFA Reagcnt a mixture of fluorescein labeled murine gamma globulin that has been shown to be non-reactive with any of the listed respiratory viruses. The buffered, stabilized, aqueous solution contains Evans Blue as a counter-stain and 0.1% sodium azide as preservative.
- Respiratory Virus Antigen Control Slides five individually packaged control slides containing wells with cell culture-derived positive and negative control cells. Each positive well is identified with the virus infected cells present, i.e., influenza A virus, influenza B virus, respiratory syncvtial virus, adenovirus, and parainfluenza virus types 1, 2 and 3. The negative well contains uninfected cultured cells. Each slide is intended to be stained only one time.
- Wash Solution Concentrate a 40X concentrate consisting of Tween 20 and 4% sodium azide (0.1% sodium azide after dilution in de-mineralized water) in a 40X phosphate buffered saline solution.
- Mounting Fluid an aqueous, buffered, stabilized solution of glycerol and . 0.1% sodium azide.
The cells to be tested, derived from a clinical specimen or cell culture, are placed onto a glass slide and allowed to air dry. The cells are fixed in acetone. The D3 Duet DFA Influenza A/Respiratory Virus Screening Reagent is added to the cells which are then incubated for 15 to 30 minutes at 35° to 37°C in a humidified chamber or humidified incubator. The stained cells are then washed with the diluted wash solution, a drop of the supplied Mounting Fluid is added and a coverslip is placed on the prepared cells. The cells are examined using a fluorescence microscope. The influenza A virus infected cells will fluoresce golden-yellow, while cells infected with any of the other six viruses will fluoresce apple-green. Uninfected cells will contain no fluorescence but will be stained rcd by the Evans Blue counter-stain. If only golden-yellow fluorescent cells are present the specimen can be reported as positive for influenza A antigen. If only apple-green fluorescent cells are present, the particular virus may be identified using the individual reagents from the DS Ultra™ DFA Respiratory Virus Screening & ID Kit (D3 Ultra) on new, separate cell preparations. If both golden-yellow and apple-green are present, the additional virus may be identified using the individual reagents from the D3 Ultra on new, separate cell preparations.
Here's a breakdown of the acceptance criteria and the study details for the D3 Duet DFA Influenza A/Respiratory Virus Screening Kit, based on the provided text:
Acceptance Criteria and Device Performance
The acceptance criteria for the D3 Duet DFA Influenza A/Respiratory Virus Screening Kit are established by demonstrating substantial equivalence to a legally marketed predicate device, the D3 Ultra DFA Respiratory Virus Screening & ID Kit (K061101). The performance is measured primarily through Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) compared to the predicate device.
Table 1: Acceptance Criteria and Reported Device Performance (Clinical Study - Direct Specimens)
| Target Virus(es) | Criterion (compared to D3 Ultra Final Identification) | Reported Device Performance (D3 Duet with 95% CI) |
|---|---|---|
| Influenza A Virus | Positive Percent Agreement (PPA) >= 95% | 99% (94.5%, 99.8%) |
| Negative Percent Agreement (NPA) >= 99% | 100% (99.7%, 100%) | |
| Influenza B, RSV, Adeno, Para 1, 2, 3 | Positive Percent Agreement (PPA) >= 99% | 100% (99.0%, 100%) |
| Negative Percent Agreement (NPA) >= 99% | 100% (99.5%, 100%) | |
| Individual Virus Performance | Sensitivity >= 90% (where applicable) | Influenza B: 100% (74.12, 100) |
| Adenovirus: 100% (93.1, 100) | ||
| Parainfluenza type 1: 100% (51.0, 100) | ||
| Parainfluenza type 2: 100% (20.1, 100) | ||
| Parainfluenza type 3: 100% (83.2, 100) | ||
| Respiratory Syncytial Virus: 100% (98.7, 100) | ||
| Specificity >= 99% (where applicable) | Influenza B, Adeno, Para 1, 2, 3, RSV: All 100% (99.6% to 99.7%, 100%) |
Table 2: Acceptance Criteria and Reported Device Performance (Clinical Study - Cultured Specimens)
| Target Virus(es) | Criterion (compared to D3 Ultra Final Identification) | Reported Device Performance (D3 Duet with 95% CI) |
|---|---|---|
| Influenza A Virus | Positive Percent Agreement (PPA) >= 95% | 100% (94.6%, 100%) |
| Negative Percent Agreement (NPA) >= 99% | 100% (98.4%, 100%) | |
| Influenza B, RSV, Adeno, Para 1, 2, 3 | Positive Percent Agreement (PPA) >= 99% | 100% (95.0%, 100%) |
| Negative Percent Agreement (NPA) >= 99% | 100% (98.4%, 100%) |
Study Details
2. Sample Size Used for the Test Set and Data Provenance
- Direct Fresh Clinical Specimens:
- Sample Size: 1184 specimens (from an initial 1203, with 19 excluded).
- Data Provenance: Prospective study conducted at three unnamed clinical sites. The country of origin is implicitly the United States as it is reviewed by the FDA.
- Cultured Clinical Specimens:
- Sample Size: 298 frozen specimens.
- Data Provenance: Conducted at a fourth unnamed clinical site (Study Site 4) using frozen specimens that were processed for cell culture. The specimens were "derived from nasopharyngeal specimens." The country of origin is implicitly the United States.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The ground truth for the clinical studies (both direct and cultured specimens) was established by comparison to a "cleared DSFA device" (D3 Ultra DFA Respiratory Virus Screening & ID Kit). While clinical experts read the comparator and subject device results, the document does not specify the number of experts used for establishing the ground truth or their qualifications beyond implying standard laboratory personnel performing the D3 Ultra assay. The D3 Ultra itself would have been interpreted by trained laboratory professionals.
4. Adjudication Method for the Test Set
The document describes comparing the D3 Duet results to the "D3 Ultra Final Identification." This implies that the D3 Ultra's result was considered the reference standard or adjudicated ground truth for the clinical studies. There is no mention of a separate adjudication panel or consensus process for discrepancies between the D3 Duet and D3 Ultra results; the D3 Ultra's result is taken as the benchmark.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was done to assess the effect size of human readers improving with AI vs. without AI assistance. The study compares the performance of the new device (D3 Duet) to a predicate device (D3 Ultra) in a standalone manner, with both being manual assays performed by laboratory personnel.
6. Standalone (Algorithm Only) Performance
Yes, the studies evaluate the D3 Duet as a standalone diagnostic device. It is a manual immunofluorescence assay performed by laboratory technicians, not an AI algorithm. Its performance is measured directly against the predicate device.
7. Type of Ground Truth Used
- For Clinical Studies (Direct and Cultured Specimens): The ground truth was the "D3 Ultra Final Identification" results. The D3 Ultra is also an immunofluorescence assay.
- For Analytical Studies (Sensitivity, Specificity, Reactivity): The ground truth was established by prepared viral stocks with known concentrations (TCID50) and identification of specific virus strains.
8. Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning or AI. This device is a manual laboratory test using monoclonal antibodies, not an AI system. The analytical and precision/reproducibility studies can be considered as validation work that informs the device's design and reliability before full clinical evaluation.
9. How the Ground Truth for the Training Set was Established
As this is not an AI/ML device, there isn't a "training set" in that sense. The development of the D3 Duet's monoclonal antibodies and reagents would have involved extensive laboratory testing and characterization against known viral isolates and cultures to establish their specificity and reactivity, analogous to establishing ground truth for individual components during development. These methods are detailed in the analytical specificity and reactivity sections, where viral strains and dilutions are tested.
§ 866.3330 Influenza virus serological reagents.
(a)
Identification. Influenza virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to influenza in serum. The identification aids in the diagnosis of influenza (flu) and provides epidemiological information on influenza. Influenza is an acute respiratory tract disease, which is often epidemic.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.