Search Results

The 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 Respiratory Syncytial Virus (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 Directigen EZ RSV antigen detection test is a chromatographic assay to detect RSV antigens extracted from various specimens of symptomatic patients. The speed and workflow of the Directigen EZ RSV test make it applicable as a "STAT" RSV antigen detection test, providing rapid, relevant information to assist with antiviral intervention and other clinical or support decisions.

Here's an analysis of the provided text regarding the acceptance criteria and supporting study for the BD Directigen™ EZ RSV assay:

This 510(k) submission (K101514) is for a modification to an already legally marketed device, the BD Directigen™ EZ RSV assay (K022133). The modification is specifically the change of controls from liquid to dry swabs. Therefore, the studies presented focus on demonstrating that these new dry controls perform equivalently and are as stable as the previously approved liquid controls, rather than a full efficacy study of the assay itself.

1. Table of Acceptance Criteria and Reported Device Performance

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

The document does not specify the exact sample sizes used for the stability and performance studies of the dry swab controls. It only states "Data to date from accelerated stability studies" and "Confirmatory real time stabilities" for stability, and "Dry swabs perform comparably in the assay" for performance.

Data Provenance: Not explicitly stated, but these are likely internal validation studies conducted by the manufacturer (Becton, Dickinson and Company). The document does not indicate country of origin for the data or if it's retrospective or prospective, though performance and stability studies are generally prospective.

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

Not applicable in the context of this submission. The ground truth here is the established performance of the previous liquid controls and the expectation that the new dry controls should match that performance. There is no mention of external experts being used for this comparison.

4. Adjudication Method for the Test Set

Not applicable. This submission concerns the performance of controls, not diagnostic interpretations requiring adjudication.

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

Not applicable. This device is a rapid chromatographic immunoassay, not an AI-powered diagnostic system, and it does not involve human readers interpreting results in a way that typically necessitates an MRMC study.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Not applicable. This is an in vitro diagnostic device, not an algorithm. The "standalone" performance here refers to the device's ability to accurately detect the RSV antigen using the new controls in laboratory settings, which is what the performance studies aimed to demonstrate.

7. The Type of Ground Truth Used

The ground truth used for these studies is the performance characteristics of the legally marketed predicate device's liquid controls. The goal was to establish that the new dry controls yield equivalent or better results (in terms of stability and assay performance) compared to the established liquid controls.

8. The Sample Size for the Training Set

Not applicable. This is an in vitro diagnostic assay with modified controls, not a machine learning algorithm requiring a "training set" in the conventional sense. The "training" for the device would have implicitly happened during its original development (K022133), but this document focuses on the validation of the control modification.

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

Not applicable, as there isn't a "training set" for an algorithm. For the original assay's development, the ground truth would have been established through a combination of clinical samples confirmed by a gold standard method (e.g., cell culture for RSV detection). However, this information is not part of this specific 510(k) submission which only addresses the control modification.

Ask a specific question about this device

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).

Ask a specific question about this device