(23 days)
The BinaxNOW® Influenza A & B Test is an in vitro immunochromatographic assay for the qualitative detection of influenza A and B nucleoprotein antigens in nasopharyngeal swab and nasal wash/aspirate specimens. It is intended to aid in the rapid differential diagnosis of influenza A and B viral infections. Negative test results should be confirmed by culture.
The BinaxNOW® Influenza A & B Test is an immunochromatographic membrane assay that uses highly sensitive monoclonal antibodies to detect influenza type A & B nucleoprotein antigens in nasopharyngeal specimens. These antibodies and a control antibody are immobilized onto a membrane support as three distinct lines and combined with other reagents/pads to construct a test strip. This test strip is mounted inside a cardboard, bookshaped hinged test device.
Swab specimens require a sample preparation step, in which the sample is eluted off the swab into elution solution or transport media. Nasal wash/aspirate samples require no preparation. Sample is added to the top of the test strip and the test device is closed. Test results are interpreted at 15 minutes based on the presence of pink-to-purple colored Sample Lines. The blue Control Line turns pink in a valid assay.
Here's an analysis of the provided text regarding the BinaxNOW® Influenza A & B Test, focusing on acceptance criteria, study details, and data provenance:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for the BinaxNOW® Influenza A & B Test are implicitly derived from its comparison to a clinical reference method (cell culture/DFA) and to its predicate devices (Binax NOW® Flu A Test and Binax NOW® Flu B Test). The study aimed to demonstrate acceptable sensitivity and specificity.
| Metric (vs. Culture/DFA) | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Influenza A: | ||
| Sensitivity | High relative to clinical need | 75% (3/4) |
| Specificity | High | 100% (110/110) |
| Influenza B: | ||
| Sensitivity | High relative to clinical need | 50% (1/2) |
| Specificity | High | 100% (112/112) |
| Metric (vs. NOW® Flu A Test) | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Influenza A: | ||
| Sensitivity | High | 100% |
| Specificity | High | 96% |
| Metric (vs. NOW® Flu B Test) | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Influenza B: | ||
| Sensitivity | High | 93% |
| Specificity | High | 97% |
Note: The document does not explicitly state numerical acceptance criteria in the typical "must achieve X% sensitivity and Y% specificity" format. Instead, the performance is presented to demonstrate substantial equivalence to established methods and predicate devices. The clinical study against culture/DFA has very small numbers of positive cases, leading to wide confidence intervals and potentially lower apparent sensitivity. The studies against the predicate Binax NOW® Flu A and B tests show much stronger performance, suggesting the extended claim focuses on maintaining equivalence to those previously cleared devices.
2. Sample Size Used for the Test Set and Data Provenance
- Clinical Study (BinaxNOW® Influenza A & B Test Performance vs. Cell Culture / DFA):
- Sample Size: 114 specimens (113 NP swab, 1 wash/aspirate).
- Data Provenance: Prospective study conducted in 2004 outside the US. Specimens collected from children (=18 years) presenting with influenza-like symptoms.
- Clinical Study (BinaxNOW® Influenza A & B Test Performance vs. Binax NOW® Flu A and Flu B Tests):
- Sample Size: 306 retrospective frozen clinical samples for Flu A comparison; 303 retrospective frozen clinical samples for Flu B comparison.
- Data Provenance: Retrospective frozen clinical samples. Collected from symptomatic patients at multiple physician offices, clinics, and hospitals in the Southern, Northeastern, and Midwestern regions of the United States, and one hospital in Sweden.
- Clinical Study (Binax NOW® Flu A and Flu B Test Performance vs. Cell Culture - for predicate devices):
- Sample Size: 373 prospective clinical samples.
- Data Provenance: Multi-center prospective study conducted during the 2002 Flu season at physician offices and clinics in the Western and mid-Atlantic United States.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify the number or qualifications of experts used to establish the ground truth.
- For the prospective study comparing the BinaxNOW® combined test to cell culture/DFA, "cell culture and/or DFA" serves as the reference standard (ground truth). It is assumed these reference methods were performed by qualified laboratory personnel, but no specifics are given.
- For the retrospective study comparing the BinaxNOW® combined test to the individual NOW® Flu A and Flu B Tests, those individual tests are treated as the reference standard.
- For the predicate device studies, "cell culture" served as the reference.
4. Adjudication Method for the Test Set
The document does not specify an adjudication method for the test set. It mentions that "Test results are interpreted at 15 minutes based on the presence of pink-to-purple colored Sample Lines. The blue Control Line turns pink in a valid assay." This suggests a single interpretation per device, without multi-reader adjudication outlined. For the analytical sensitivity, 12 different operators interpreted devices to determine the LOD.
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
No MRMC comparative effectiveness study was done. This device is an in vitro diagnostic (IVD) rapid immunoassay, not an AI-assisted diagnostic tool for interpretation by human readers. The output is a visual presence or absence of a line on a test strip.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, the performance data presented are for the device (the BinaxNOW® Influenza A & B Test) as a standalone diagnostic tool. It is a rapid immunoassay that outputs a visual result, which is then interpreted by a human, but the performance metrics provided (sensitivity, specificity) reflect the device's ability to detect the antigen itself, not the human interpreter's performance. The analytical studies (analytical sensitivity, reactivity testing, analytical specificity) are also standalone performance evaluations of the device.
7. The Type of Ground Truth Used
- Clinical Study (BinaxNOW® Influenza A & B Test Performance vs. Cell Culture / DFA): Cell Culture and/or Direct Fluorescent Antibody (DFA). This is a laboratory-based reference standard.
- Clinical Study (BinaxNOW® Influenza A & B Test Performance vs. Binax NOW® Flu A and Flu B Tests): The individual Binax NOW® Flu A and Flu B Tests (predicate devices) were used as the reference standard.
- Clinical Study (Binax NOW® Flu A and Flu B Test Performance vs. Cell Culture - for predicate devices): Cell Culture.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of device development (e.g., machine learning training). As a rapid immunoassay, this device relies on biological interactions (antibody-antigen binding) rather than a trained algorithm. The various analytical and clinical studies serve to validate its performance.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no mention of a "training set" in the machine learning sense for this immunochromatographic device. The development and optimization of such assays would involve extensive in-house testing using characterized positive and negative samples, but these are not typically referred to as a "training set" in the regulatory context for IVDs.
§ 866.3328 Influenza virus antigen detection test system.
(a)
Identification. An influenza virus antigen detection test system is a device intended for the qualitative detection of influenza viral antigens directly from clinical specimens in patients with signs and symptoms of respiratory infection. The test aids in the diagnosis of influenza infection and provides epidemiological information on influenza. Due to the propensity of the virus to mutate, new strains emerge over time which may potentially affect the performance of these devices. Because influenza is highly contagious and may lead to an acute respiratory tract infection causing severe illness and even death, the accuracy of these devices has serious public health implications.(b)
Classification. Class II (special controls). The special controls for this device are:(1) The device's sensitivity and specificity performance characteristics or positive percent agreement and negative percent agreement, for each specimen type claimed in the intended use of the device, must meet one of the following two minimum clinical performance criteria:
(i) For devices evaluated as compared to an FDA-cleared nucleic acid based-test or other currently appropriate and FDA accepted comparator method other than correctly performed viral culture method:
(A) The positive percent agreement estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 80 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 70 percent.
(B) The negative percent agreement estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 95 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 90 percent.
(ii) For devices evaluated as compared to correctly performed viral culture method as the comparator method:
(A) The sensitivity estimate for the device when testing for influenza A must be at the point estimate of at least 90 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 80 percent. The sensitivity estimate for the device when testing for influenza B must be at the point estimate of at least 80 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 70 percent.
(B) The specificity estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 95 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 90 percent.
(2) When performing testing to demonstrate the device meets the requirements in paragraph (b)(1) of this section, a currently appropriate and FDA accepted comparator method must be used to establish assay performance in clinical studies.
(3) Annual analytical reactivity testing of the device must be performed with contemporary influenza strains. This annual analytical reactivity testing must meet the following criteria:
(i) The appropriate strains to be tested will be identified by FDA in consultation with the Centers for Disease Control and Prevention (CDC) and sourced from CDC or an FDA-designated source. If the annual strains are not available from CDC, FDA will identify an alternative source for obtaining the requisite strains.
(ii) The testing must be conducted according to a standardized protocol considered and determined by FDA to be acceptable and appropriate.
(iii) By July 31 of each calendar year, the results of the last 3 years of annual analytical reactivity testing must be included as part of the device's labeling. If a device has not been on the market long enough for 3 years of annual analytical reactivity testing to have been conducted since the device received marketing authorization from FDA, then the results of every annual analytical reactivity testing since the device received marketing authorization from FDA must be included. The results must be presented as part of the device's labeling in a tabular format, which includes the detailed information for each virus tested as described in the certificate of authentication, either by:
(A) Placing the results directly in the device's § 809.10(b) of this chapter compliant labeling that physically accompanies the device in a separate section of the labeling where the analytical reactivity testing data can be found; or
(B) In the device's label or in other labeling that physically accompanies the device, prominently providing a hyperlink to the manufacturer's public Web site where the analytical reactivity testing data can be found. The manufacturer's home page, as well as the primary part of the manufacturer's Web site that discusses the device, must provide a prominently placed hyperlink to the Web page containing this information and must allow unrestricted viewing access.
(4) If one of the actions listed at section 564(b)(1)(A)-(D) of the Federal Food, Drug, and Cosmetic Act occurs with respect to an influenza viral strain, or if the Secretary of Health and Human Services (HHS) determines, under section 319(a) of the Public Health Service Act, that a disease or disorder presents a public health emergency, or that a public health emergency otherwise exists, with respect to an influenza viral strain:
(i) Within 30 days from the date that FDA notifies manufacturers that characterized viral samples are available for test evaluation, the manufacturer must have testing performed on the device with those viral samples in accordance with a standardized protocol considered and determined by FDA to be acceptable and appropriate. The procedure and location of testing may depend on the nature of the emerging virus.
(ii) Within 60 days from the date that FDA notifies manufacturers that characterized viral samples are available for test evaluation and continuing until 3 years from that date, the results of the influenza emergency analytical reactivity testing, including the detailed information for the virus tested as described in the certificate of authentication, must be included as part of the device's labeling in a tabular format, either by:
(A) Placing the results directly in the device's § 809.10(b) of this chapter compliant labeling that physically accompanies the device in a separate section of the labeling where analytical reactivity testing data can be found, but separate from the annual analytical reactivity testing results; or
(B) In a section of the device's label or in other labeling that physically accompanies the device, prominently providing a hyperlink to the manufacturer's public Web site where the analytical reactivity testing data can be found. The manufacturer's home page, as well as the primary part of the manufacturer's Web site that discusses the device, must provide a prominently placed hyperlink to the Web page containing this information and must allow unrestricted viewing access.