Search Results

The Diagnostic Hybrids, Inc. device, D3 FastPoint L-DFA Influenza A/Influenza B Virus Identification Kit is intended for the qualitative identification of influenza A virus and influenza B virus in nasal and nasopharyngeal swabs and aspirates/washes specimens from patients with signs and symptoms of respiratory infection by direct detection of immunofluorescence using monoclonal antibodies (MAbs).

It is recommended that specimens found to be negative for influenza A or influenza B virus after examination of the direct specimen result be confirmed by cell culture. Negative results do not preclude influenza A or influenza B 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. Since influenza strains display antigenic drift and shift from year to year, performance characteristics may vary. If infection with a novel influenza A virus is suspected, based on clinical and epidemiological screening criteria communicated by public health authorities, collect specimens following appropriate infection control precautions and submit to state or local health departments, for testing. Viral culture should not be attempted in these cases unless a BSL 3+facility' is available to receive and culture specimens .

The D3 FastPoint L-DFA Influenza A/Influenza B Virus Identification Kit (D3 FastPoint A/B Kit) uses a blend (called a "L-DFA Reagent") of viral antigen-specific murine monoclonal antibodies that are directly labeled with either R-PE (influenza A virus) or fluorescein (influenza B virus) for the rapid identification of influenza A virus and influenza B virus in nasal and nasopharyngeal swabs and aspirates/washes specimens from patients with signs and symptoms of respiratory infection.

The cells to be tested are derived from respiratory specimens from patients with signs and symptoms of respiratory infection. The cells are permeabilized and stained concurrently in a liquid suspension format with the L-DFA reagent. After incubating at 35℃ to 37℃ for 5-minutes, the stained cell suspensions are rinsed with 1X PBS. The rinsed cells are pelleted by centrifugation and then re-suspended with the re-suspension buffer and loaded onto a specimen slide well. The cells are examined using a fluorescence microscope. Cells infected with influenza A virus will exhibit goldenyellow fluorescence due to the PE. Cells infected with influenza B virus will exhibit apple-green fluorescence due to the FITC. Non-infected cells will exhibit red fluorescence due to the Evans Blue counter-stain. Nuclei of intact cells will exhibit orange-red fluorescence due to the propidium iodide.

Here's a breakdown of the acceptance criteria and the study details for the D³ FastPoint L-DFA Influenza A/Influenza B Virus Identification Kit:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" in a quantitative format for clinical performance beyond the presented sensitivity and specificity. However, based on the clinical trial results, these would be the implied performance metrics.

Analytical Performance (Reproducibility):

Analytical Performance (Limit of Detection - LoD):

Analytical Reactivity (Inclusivity):

The document states "MAbs are reactive with all listed strains" for both Influenza A and B. The acceptance criterion is implicitly 100% reactivity with the tested strains. The reported performance confirms this by showing detection of a specified number of fluorescent cells for all tested strains at 20x LoD.

2. Sample Size Used for the Test Set and Data Provenance:

• Clinical Test Set Sample Size:
  • Total Specimens Evaluated: 1519
  • Nasal/Nasopharyngeal Wash/Aspirate (Influenza A): 637 specimens
  • Nasal/Nasopharyngeal Wash/Aspirate (Influenza B): 628 specimens
  • Nasal/Nasopharyngeal Swab (Influenza A): 690 specimens
  • Nasal/Nasopharyngeal Swab (Influenza B): 711 specimens (Note: Summing these individual specimen counts for A and B across different sample types is not appropriate to get a single "total," as the same specimen might be tested for both A and B, and different subsets might be used for different sample types or sites.)
• Data Provenance: Prospective collection from symptomatic individuals suspected of respiratory infection in 4 geographically diverse U.S. clinical laboratories during the 2009 respiratory virus season (January 2009 - March 2009). The specimens were "excess, remnants" that would have otherwise been discarded, implying real-world clinical samples.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:

The document describes the ground truth as a "predetermined algorithm that used composite comparator methods" involving an FDA-cleared Direct Specimen Fluorescent Antibody (DSFA) test and viral culture confirmation. This method does not explicitly state the involvement of human experts establishing the ground truth beyond the likely requirement of trained laboratory personnel to perform and interpret the comparator tests. Therefore, details on the number and qualifications of experts for ground truth establishment are not provided in this document.

4. Adjudication Method for the Test Set:

The ground truth was established using a "composite comparator method":

• "True" positive: Any sample that tested positive by either the comparator DSFA test OR viral culture.
• "True" negative: Any sample that tested negative by BOTH the comparator DSFA test AND viral culture.
  This is a form of adjudication by algorithm/composite reference standard rather than human consensus.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was Done:

No, a Multi Reader Multi Case (MRMC) comparative effectiveness study of human readers with vs. without AI assistance was not done. The study compared the device (D3 FastPoint A/B Kit) directly against a composite reference standard, not against human readers. This device is a diagnostic kit, not an AI or imaging device that would typically involve human reader studies for interpretation.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done:

Yes, the performance presented for the D3 FastPoint L-DFA Influenza A/Influenza B Virus Identification Kit is a standalone performance of the device (kit) itself, as read and interpreted by laboratory personnel according to its instructions. It is not an "algorithm" in the modern AI sense, but a lab kit where the reported accuracy reflects the kit's ability to correctly identify the viruses based on fluorescence.

7. The Type of Ground Truth Used:

The ground truth used was a composite reference standard consisting of:

• An FDA-cleared Direct Specimen Fluorescent Antibody (DSFA) test.
• Viral culture confirmation for all negatives from the comparator DSFA test.

8. The Sample Size for the Training Set:

The document does not explicitly mention a separate "training set" for the D3 FastPoint L-DFA Influenza A/Influenza B Virus Identification Kit in the context of machine learning or algorithm development. This device is a traditional in-vitro diagnostic kit. Its development would involve analytical studies and optimization (e.g., antibody selection, reagent formulation) rather than a separate "training set" in the AI sense.

However, the "Analytical Reactivity (inclusivity)" study, which tested the reactivity against 13 influenza A strains and 7 influenza B strains, could be considered part of the analytical development and validation process to ensure the kit's broad detection capabilities for known strains.

9. How the Ground Truth for the Training Set Was Established:

As there is no explicitly defined "training set" in the AI sense for this traditional diagnostic kit, the concept of establishing ground truth for a training set is not applicable here. The analytical studies (like inclusivity) involved preparing known infected cell suspensions with specified viral strains, where the "ground truth" was inherent in the preparation of these controlled samples.

Ask a specific question about this device