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The Binax NOW® RSV Test is a rapid immunochromatographic assay for the qualitative detection of respiratory syncycial virus (RSV) fusion protein antigen in nasal wash and nasopharyngeal swab specimens from sympromatic patients. This test is intended for in virro diagnostic use to aid in the diagnosis of RSV infections in neonatal and pediatric patients under the age of five. It is recommended that negative test results be confirmed by culture.

The Binax NOW RSV Test is an immunochromatographic membrane assay used to detect RSV antigen in nasopharyngeal specimens. A test scrip, containing gold-conjugated and immobilized and -RSV ancibodies, is mounted on the right side of a cardboard, book-shaped hinged test device. Swab specimens and patients) require a sample preparation seep, in which the sample is eluted off the swab into transport media or saline. Nasal wash samples do not require any preparation. The sample to be tested is added to a pad at the top of the rest strip, and the rest device is closed. RSV antigen present in the sample reacts to bind anti-RSV conjugated antibody. The resulting antigen-conjugate complexes are captured by immobilized anti-RSV antibody, forming the Sample Line Immobilized Control Line antibody, which appears as a blue line in an uncested device, captures a visualizing conjugate, forming a pink Control Line. The sample is contained, and results are available within 15 minutes.

Acceptance Criteria and Device Performance Study for Binax NOW® RSV Test

1. Table of Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state acceptance criteria as numerical targets. Instead, the study aims to establish "substantial equivalence" to a predicate device. The performance is reported in terms of sensitivity and specificity against viral cell culture (or DFA/viral cell culture for nasopharyngeal swabs). We can infer the "acceptance criteria" were implied to be comparable performance to existing methods.

2. Sample Sizes and Data Provenance

Nasal Wash - Retrospective Study:

• Sample Size: 59 viral cultured nasal wash specimens.
• Data Provenance: Obtained from a teaching university/medical center in the northeast (USA, presumably). Retrospective.

Nasal Wash - Prospective Study:

• Sample Size: 191 nasal wash specimens.
• Data Provenance: Multi-center, prospective study. Country of origin not specified, but context suggests USA.

Nasopharyngeal Swab - Prospective Study:

• Sample Size: 179 nasopharyngeal swab specimens.
• Data Provenance: Multi-center, prospective study. Country of origin not specified, but context suggests USA.

Reproducibility Study:

• Sample Size: 234 coded specimens (panel containing negative, low positive, and low/moderate positive controls).
• Data Provenance: Blind study conducted at 3 separate sites. Country of origin not specified, but context suggests USA.

3. Number of Experts and Qualifications for Ground Truth

The document does not specify the number or qualifications of experts used to establish the ground truth (viral cell culture or DFA/viral cell culture). It only states that performance was calculated "using standard methods."

4. Adjudication Method for the Test Set

The document does not describe any adjudication method for the test set.

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

There is no indication that a multi-reader multi-case (MRMC) comparative effectiveness study was done, or any analysis of how human readers improve with AI vs without AI assistance. The device is an immunochromatographic assay, not an AI-powered diagnostic.

6. Standalone (Algorithm Only) Performance

The device is a rapid immunochromatographic assay. The reported clinical sensitivity and specificity studies reflect the standalone performance of the device (algorithm only, as there is no human interpretation component beyond reading the visible lines).

7. Type of Ground Truth Used

• Clinical Studies (Nasal Wash): Viral cell culture.
• Clinical Studies (Nasopharyngeal Swab): DFA/viral cell culture (Direct Fluorescent Antibody / viral cell culture).

8. Sample Size for the Training Set

The document does not specify a separate training set size. The device is a lateral flow immunoassay, not a machine learning algorithm that typically requires a large training dataset in the same way. The development and optimization of the assay would involve internal validation and development studies, but these are not referred to as statistical "training sets" in this context.

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

Given that this is an immunochromatographic assay and not an AI/machine learning device, the concept of a "training set" with ground truth established in the typical sense for algorithms is not applicable. The development of such a device involves:

• Selection and optimization of antibodies and reagents.
• Establishing critical concentrations and cutoff points through empirical testing with known positive and negative samples (controls, characterized clinical isolates).
• Analytic reactivity and specificity testing (as mentioned in the summary) to ensure proper functioning.

The "ground truth" for these development phases would be based on well-characterized viral isolates, clinical samples confirmed by reference methods (like cell culture), and purified substances.

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The BD Directigen™ EZ RSV test is a rapid chromatographic immunoassay for the direct and qualitative detection of Respiratory Syncytial Virus (RSV) antigen in nasopharyngeal washes, nasopharyngeal aspirates, nasopharyngeal swabs, and nasopharyngeal swab/washes from patients suspected of having a viral respiratory infection. This test is intended for in vitro diagnostic use to aid in the diagnosis of RSV infections in neonatal and pediatric patients under the age of 20. It is recommended that negative test results be confirmed by cell culture.

The BD Directigen™ EZ RSV test is a chromatographic assay to qualitatively detect RSV antigen in samples extracted from respiratory specimens. When extracted specimens are added to the test device, RSV A and/or B antigens bind to anti-RSV conjugated to visualizing particles in the test strip. The antigenconjugate 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 indicated by the appearance of two reddish purple lines in the read window, one line next to the Test "T" and the other next to the Control "C". The absence of a reddish purple line next to the "T" and the presence of a reddish purple line next to the "C" indicate a negative result. The test is considered uninterpretable if no visible reddish purple line is present next to the "C".

The BD Directigen™ EZ RSV test is a rapid chromatographic immunoassay designed for the direct and qualitative detection of Respiratory Syncytial Virus (RSV) antigen. The acceptance criteria and performance data are summarized below, based on the provided 510(k) summary.

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state pre-defined acceptance criteria values for the clinical performance metrics (sensitivity and specificity). Instead, it presents the device's performance compared to predicate methods and establishes "substantial equivalence." However, we can infer the achieved performance from the clinical study results.

Inferred Clinical Performance Acceptance Criteria and Reported Performance:

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

• Sample Size for Clinical Test Set: 1176 specimens.
• Data Provenance: The clinical study was a multicenter trial conducted during the 2001-2002 RSV season. The country of origin is not explicitly stated, but given the submission is to the U.S. FDA by Becton, Dickinson and Company (with a Maryland address), it is highly likely the data is from the United States. The study appears to be prospective as it evaluates current patients suspected of having RSV during a specific season.

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

The ground truth for the primary clinical performance comparison was viral cell culture and Direct Fluorescent Antibody (DFA) tests. These are laboratory-based diagnostic methods, not human expert consensus, for establishing true positives and negatives for RSV infection. Therefore, information on the "number of experts" or their "qualifications" in the traditional sense of interpreting images or clinical cases is not applicable here. The ground truth relies on the established accuracy and interpretation protocols of these comparators.

For discrepant resolution (culture negative, BD Directigen™ EZ RSV positive specimens), PCR testing was performed. Again, this is a laboratory test, not expert interpretation.

4. Adjudication Method for the Test Set

The primary adjudication method involved comparing the BD Directigen™ EZ RSV test results directly against viral cell culture. For specimens where the BD Directigen™ EZ RSV test was positive but cell culture was negative, PCR testing was used for further resolution. This can be considered a form of discrepant analysis or reference standard reconciliation.

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

This device is a rapid chromatographic immunoassay, not an AI-based imaging or interpretive device. Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable to this product. The device itself provides a direct result.

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

Yes, the clinical performance study evaluated the standalone performance of the BD Directigen™ EZ RSV test. The device produces a direct qualitative result (positive, negative, or uninterpretable) that is read visually, but the device itself is the "algorithm only" in the sense that it performs the detection without human interpretive judgment of complex patterns.

7. The Type of Ground Truth Used

The primary ground truth used for the clinical performance evaluation was viral cell culture. For discrepant results (culture negative, EZ RSV positive), PCR testing was used as a supplemental ground truth.

8. The Sample Size for the Training Set

The document does not explicitly mention a separate "training set" in the context of device development. For an immunoassay like this, the development typically involves analytical testing (LOD, cross-reactivity, interference, etc.) and then clinical validation. There isn't a machine learning model that needs a training set in the conventional sense. The "training" of the assay involves optimizing reagent concentrations and manufacturing processes.

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

As explained above, a "training set" in the context of machine learning and its associated ground truth establishment is not applicable to this immunoassay device. The foundational data for optimizing the assay would come from analytical studies (e.g., testing known viral strains at various concentrations, known interfering substances).

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