(169 days)
The Diagnostic Hybrids, Inc. device, D3 Duet DFA RSV/Respiratory Virus Screening Kit, is intended for the qualitative detection and identification of respiratory syncytial virus, while screening for influenza A virus, influenza B 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. 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, D3 Duet DFA RSV/Respiratory Virus Screening Kit, uses a blend of viral antigen-specific murine MAbs. MAbs for RSV are directly labeled with R-phycoerythrin (R-PE) for the rapid detection and identification of RSV. MAbs for influenza A virus, influenza B 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 RSV/Respiratory Virus Screening Reagent
- Normal Mouse Gamma Globulin DFA Reagent
- Respiratory Virus Antigen Control Slides
- Wash Solution Concentrate
- Mounting Fluid
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 RSV/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 respiratory syncytial 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 red by the Evans Blue counter-stain. If only golden-yellow fluorescent cells are present the specimen can be reported as positive for respiratory syncytial virus antigen. If only apple-green fluorescent cells are present, the particular virus is identified using the individual reagents from the D3 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 study details for the D' DUET DFA RSV/RESPIRATORY VIRUS SCREENING KIT:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are not explicitly stated as numerical targets for sensitivity and specificity in the provided text. Instead, the study uses the legally marketed predicate device (D3 Ultra DFA Respiratory Virus Screening & ID Kit) as the comparator, and "100% agreement" is repeatedly cited as the performance goal versus this comparator. The device met this implicit acceptance criterion by demonstrating 100% agreement in both positive and negative percentage agreements across various virus types and specimen sources.
| Virus Target(s) | Specimen Type | Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance | 95% Confidence Interval |
|---|---|---|---|---|---|
| RSV | Direct (Nasal/NP) | PPA (Positive Percent Agreement) | 100% | 100% (300/300) | 97.8% - 100% |
| Direct (Nasal/NP) | NPA (Negative Percent Agreement) | 100% | 100% (887/887) | 99.6% - 100% | |
| IAFVBAPF123* | Direct (Nasal/NP) | PPA (Positive Percent Agreement) | 100% | 100% (186/186) | 98.0% - 100% |
| IAFVBAPF123* | Direct (Nasal/NP) | NPA (Negative Percent Agreement) | 100% | 100% (1001/1001) | 99.6% - 100% |
| RSV | Cultured Specimens | PPA (Positive Percent Agreement) | 100% | 100% (33/33) | 89.5% - 100% |
| Cultured Specimens | NPA (Negative Percent Agreement) | 100% | 100% (265/265) | 98.6% - 100% | |
| IAFVBAPF123* | Cultured Specimens | PPA (Positive Percent Agreement) | 100% | 100% (104/104) | 96.4% - 100% |
| IAFVBAPF123* | Cultured Specimens | NPA (Negative Percent Agreement) | 100% | 100% (194/194) | 98.1% - 100% |
*IAFVBAPF123 refers to Influenza A virus, Influenza B virus, Adenovirus, and Parainfluenza virus types 1, 2, and 3.
2. Sample Sizes and Data Provenance
- Direct Fresh Specimens (Test Set):
- Total Initial Specimens: 1203
- Excluded Specimens: 17 (due to site deviations, duplicate specimen, insufficient cell numbers, or high background)
- Analyzed Specimens: 1187
- Data Provenance: Prospective, collected at three study sites in the United States.
- Cultured Specimens (Test Set):
- Total Specimens: 298 frozen specimens
- Data Provenance: Retrospective (frozen specimens), from a fourth study site. All specimens were derived from nasopharyngeal specimens. The age distribution of individuals is provided on page 13.
3. Number of Experts and Qualifications
The document does not explicitly state the number of experts used to establish ground truth for the test set or their specific qualifications (e.g., "Radiologist with 10 years of experience"). However, it mentions that the D3 Duet device was compared against a "cleared DSFA device" (D3 Ultra DFA Respiratory Virus Screening & ID Kit) as the comparator. This implies that the ground truth for the clinical studies was established by laboratory personnel using the predicate device, which is a standard immunofluorescence assay.
4. Adjudication Method
The document does not specify an adjudication method like 2+1 or 3+1. The results are presented as direct comparisons between the D3 Duet and the "D3 Ultra Final Identification," implying that the D3 Ultra's results served as the reference standard without further expert adjudication beyond its own established interpretation protocol.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No multi-reader multi-case (MRMC) comparative effectiveness study was done. This device is a diagnostic kit read by a single trained technician, not an AI system designed to assist human readers. Therefore, the effect size of human readers improving with AI vs. without AI assistance is not applicable.
6. Standalone Performance
Yes, a standalone performance study (algorithm only without human-in-the-loop performance) was done for the D3 Duet. The entire clinical performance section (pages 11-14) reports the performance of the D3 Duet device independently against the predicate device (D3 Ultra) as the gold standard.
7. Type of Ground Truth Used
The ground truth for the clinical studies was established using a cleared comparator device, specifically the D3 Ultra DFA Respiratory Virus Screening & ID Kit. This is a form of reference standard testing using an established laboratory method (immunofluorescence assay) for viral antigen detection. For the cultured specimens, cell culture methods were also employed.
8. Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of an AI/algorithm. Instead, the device is a diagnostic kit based on monoclonal antibodies. Therefore, there is no sample size for an algorithm training set. The various analytical and non-clinical performance studies (precision, detection limit, analytical reactivity, analytical specificity) act as development and validation steps for the kit itself, rather than training for an AI.
9. How Ground Truth for the Training Set Was Established
As there is no "training set" for an AI/algorithm, this point is not applicable. The development and validation of the D3 Duet kit relied on established laboratory techniques for virus isolation, identification using cell cultures, reference viral strains, and bacterial/fungal cultures. These methods served as the "ground truth" during the development and analytical validation of the antibody blend and assay performance.
§ 866.3480 Respiratory syncytial virus serological reagents.
(a)
Identification. Respiratory syncytial virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to respiratory syncytial virus in serum. Additionally, some of these reagents consist of respiratory syncytial virus antisera conjugated with a fluorescent dye (immunofluorescent reagents) and used to identify respiratory syncytial viruses from clinical specimens or from tissue culture isolates derived from clinical specimens. The identification aids in the diagnosis of respiratory syncytial virus infections and provides epidemiological information on diseases caused by these viruses. Respiratory syncytial viruses cause a number of respiratory tract infections, including the common cold, pharyngitis, and infantile bronchopneumonia.(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 § 866.9.