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The BD Directigen™ EZ Flu A+B test is a rapid chromatographic immunoassay for the direct and qualitative detection of influenza A and B viral antigens from nasopharyngeal washes/aspirates and throat swabs of symptomatic patients. The BD Directigen™ EZ Flu A+B test is a differentiated test, and therefore influenza A viral antigens can be distinguished from influenza B viral antigens from a single processed sample using a single device. The test is to be used as an aid in the diagnosis of influenza A and B viral infections. All negative test results should be confirmed by cell culture.

The BD Directigen™ EZ Flu A+B test is a chromatographic assay to qualitatively detect influenza A and B viral antigens in samples processed from respiratory specimens. When specimens are processed and added to the test device, influenza A and/or B viral antigens bind to anti-influenza antibodies conjugated to visualizing particles in the corresponding A and B test strips. The antigen-conjugate complex migrates across the test strip to the reaction area and is captured by the line of antibody on the membrane. A positive result is visualized as a reddish purple line at the Test "T" position in the Flu A or Flu B read window in combination with a reddish purple line at the Control "C".

Here's an analysis of the acceptance criteria and study details for the BD Directigen™ EZ Flu A+B, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state pre-defined acceptance criteria in terms of specific sensitivity and specificity thresholds. Instead, it demonstrates "substantial equivalence" to predicate devices and viral cell culture. The reported performance values are:

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

The text states: "Performance characteristics of the BD Directigen EZ Flu A+B test were determined by calculating sensitivity and specificity of the BD Directigen EZ Flu A+B test compared to culture for prospectively collected nasopharyngeal wash/aspirate and throat specimens in both an adult and pediatric population."

• Test Set Sample Size: The exact numerical sample size for the clinical study (test set) is not explicitly provided in the document.
• Data Provenance: The data was prospectively collected from a multi-center study that was "geographically diverse." The country of origin is not specified, but given the submission to the FDA, it is highly likely to be the USA. The specimens were from "symptomatic patients."

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

The ground truth for the clinical study was established by viral cell culture. This is a laboratory method, not reliant on human expert interpretation in the same way an imaging study would be. Therefore, the concept of "number of experts" and their "qualifications" doesn't directly apply here for establishing the primary ground truth.

4. Adjudication Method for the Test Set

As the primary ground truth was established by viral cell culture, there was no human adjudication method described for the test set interpretation itself. The BD Directigen™ EZ Flu A+B test results were compared against the cell culture results.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance

• No MRMC study was done. This device is a rapid diagnostic test (an immunoassay) for direct antigen detection, not an AI-powered diagnostic tool intended for interpretation by human readers. Therefore, the concept of human reader improvement with AI assistance is not applicable.

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

• Yes, a standalone study was done. The clinical performance reported (sensitivity and specificity) is for the BD Directigen™ EZ Flu A+B test operating as a standalone diagnostic device, comparing its results directly to cell culture. There is no human-in-the-loop element mentioned for the primary output of this device.

7. The Type of Ground Truth Used

• The primary ground truth used for the clinical performance evaluation was viral cell culture.
• The device was also compared to Direct Fluorescent Antibody (DFA) tests, the BD Directigen™ Flu A+B test, and the Remel Xpect™ FLU A/B test in a "device comparison" context, suggesting these served as secondary or comparative ground truths/references.

8. The Sample Size for the Training Set

• The document does not provide any information regarding a "training set" or its sample size. This is typical for traditional (non-AI/machine learning) diagnostic devices. The device's performance is established through analytical and clinical validation, not by training a model on a dataset.

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

• As there is no mention of a training set, the method for establishing its ground truth is not applicable and not provided.

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The QuickVue Influenza A + B test allows for the rapid, qualitative detection of influenza type A and type B antigens directly from nasal swab, nasal wash and nasal aspirate specimens. The test is intended for use as an aid in the rapid differential diagnosis of acute influenza type A and type B viral infections. The test is not intended to detect influenza C antigens. The test is intended for professional and laboratory use.

The QuickVue Influenza A + B test, the successor product to the QuickVue Influenza test, has two Test Line indicators - one for type A and one for type B. The two Test Line indicators allow for the separate identification of type A and type B viral antigens from the same specimen. If either Test Line turns pinkto-red, the test is positive for influenza. Nasal swabs, nasal wash and/or nasal aspirates serve as specimens for this test. The patient specimen is placed in a tube containing Extraction Reagent, during which time the virus particles in the specimen are disrupted, exposing internal viral antigens. After extraction, the Test Strip is placed in the Extraction Tube for 10 minutes. During this time, the extracted specimen will react with the reagents in the Test Strip. If the extracted specimen contains influenza Type A and/or B antigens, a pink-to-red Test Line along with a blue procedural Control Line will appear on the Test Strip. If influenza Type A and B viral antigens are not present, or present at very low levels, only a blue procedural Control Line will appear. If no blue procedural Control Line develops, the result is considered invalid.

Here's a breakdown of the acceptance criteria and study information for the QuickVue® Influenza A + B test, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The provided text does not explicitly state pre-defined acceptance criteria (e.g., a specific sensitivity or specificity percentage target). Instead, it states that "Substantial equivalence has been demonstrated between the QuickVue test and viral culture for the qualitative detection of influenza Type A and B antigens." This implies that the device's performance, as measured in comparison to viral culture, was deemed acceptable by the FDA for establishing substantial equivalence to predicate devices.

However, the specific quantitative performance metrics (sensitivity, specificity) from the clinical study are not provided in this summary.

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

• Sample Size for Test Set: Not explicitly stated in the provided text. The text mentions a "multi-clinical field study" but does not give the number of clinical specimens.
• Data Provenance:
  • Country of Origin: Not explicitly stated.
  • Retrospective or Prospective: Retrospective. The text states: "a retrospective comparison of the QuickVue Influenza A + B test to viral culture was conducted in a multi-clinical field study."

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

This information is not provided in the document. The ground truth was established by "viral culture." The qualifications of those performing or interpreting the viral culture are not specified.

4. Adjudication Method for the Test Set

This information is not provided in the document.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

• Was it done? No. This type of study is not mentioned. The device is a "standalone" or "algorithm only" type of diagnostic, meaning human interpretation is based on the visible lines on the test strip, not assisted by an AI.
• Effect Size of Human Readers with AI vs. Without AI Assistance: Not applicable, as no AI assistance is mentioned.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

• Was it done? Yes, implicitly. The QuickVue® Influenza A + B test is a lateral-flow immunoassay, which is a standalone device providing a direct result (pink-to-red test line, blue control line) without human-in-the-loop AI assistance. The clinical study evaluated the performance of this device on its own.

7. Type of Ground Truth Used

• Ground Truth: Viral culture. The text states: "Substantial equivalence has been demonstrated between the QuickVue test and viral culture..."

8. Sample Size for the Training Set

This information is not provided in the document. As this is an immunoassay and not an AI/machine learning device, the concept of a "training set" in the context of data for model development is typically not applicable. The device's "training" would be its design and optimization during manufacturing and R&D phases.

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

Not applicable, as a "training set" for an AI/ML model is not relevant for this immunodiagnostic device.

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