Search Results

The Sofia Influenza A+B FIA employs immunofluorescence to detect influenza B viral nucleoprotein antigens in direct nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash specimens and nasopharyngeal swab and nasopharyngeal aspirate/wash specimens in transport media from symptomatic patients. This qualitative test is intended for use as an aid in the rapid differential diagnosis of acute influenza B viral infections. The test is not intended to detect influenza C antigens. A negative test is recommended these results be confirmed by viral culture or an FDA-cleared influenza A and B molecular assay. Negative results do not preclude influenza virus infections and should not be used as the sole basis for treatment or other patient management decisions. This test is intended for professional and laboratory use.

The Sofia Influenza A+B FIA may be used with Sofia or Sofia 2.

Performance characteristics for influenza A and B were established during February through March 2011 when influenza viruses A/California 7/2009 (2009 H1N1), A/Perth/16/2009 (H3N2), and B/Brisbane/60/2008 (Victoria-Like) were the predominant influenza viruses in circulation according to the Mortality Weekly Report from the CDC entitled "Update: Influenza Activity--United States, 2010-2011 Season, and Composition of the 2011-2012 Influenza Vaccine." Performance characteristics may vary against other emerging influenza viruses.

If infection with a novel influenza virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, samples should be collected with appropriate infection sor novel virulent influenza viruses and sent to state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture samples.

The Sofia Influenza A+B FIA employs immunofluorescence technology that is used with Sofia and Sofia 2 to detect influenza virus nucleoproteins. This test allows for the differential detection of influenza A and influenza B antigens.

The patient sample is placed in the Reagent Tube, during which time the virus particles in the sample are disrupted, exposing internal viral nucleoproteins. After disruption, the sample is dispensed into the Test Cassette sample well. From the sample migrates through a test strip containing various unique chemical environments. If influenza viral antigen is present, they will be trapped in a specific location.

Note: Depending upon the user's choice, the Test Cassette is either placed inside of Sofia or Sofia 2 for automatically timed development (WALK AWAY Mode) or placed on the counter or bench top for a manually timed development and then placed into Sofia 2 to be scanned (READ NOW Mode).

Sofia and Sofia 2 will scan the test strip and measure the fluorescent signal by processing the results using method-specific algorithms. Sofia and Sofia 2 will display the test results (Positive, or Invalid) on the screen. The results can also be automatically printed on an integrated printer if this option is selected.

Sofia 2 is a microprocessor-controlled device about the size of a desk top telephone and weighs less than 3 pounds. Sofia 2 uses a fluorescent tag that is illuminated by an Ultraviolet (UV) light source to generate specific results.

The provided text describes the 510(k) premarket notification for the "Sofia® Influenza A+B FIA on Sofia 2" device. Here's an analysis of the acceptance criteria and the study information:

1. Table of Acceptance Criteria and Reported Device Performance:

The document does not explicitly state acceptance criteria in a quantitative, objective manner (e.g., "sensitivity must be >95%"). Instead, the performance studies aim to demonstrate equivalence to the predicate device (Sofia® Influenza A+B FIA on Sofia). Therefore, the "reported device performance" is framed as proving this equivalence.

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

The document mentions a "panel of clinical samples" for the Method Comparison study but does not specify the sample size for this test set nor the specific number of samples used for other studies like LoD, Precision, Early Read, or Reproducibility.

The data provenance is described as:

• "Performance characteristics for influenza A and B were established during February through March 2011"
• Location: Implied to be United States, as it references the "Morbidity and Mortality Weekly Report from the CDC entitled 'Update: Influenza Activity—United States, 2010-2011 Season'".
• Retrospective/Prospective: The collection period (Feb-Mar 2011) and subsequent analysis suggest the data might be retrospective (collected on previously circulating strains and then tested with the devices).

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

The document does not provide information on the number of experts or their qualifications for establishing ground truth for the test set.

4. Adjudication Method for the Test Set:

The document does not explicitly describe an adjudication method (e.g., 2+1, 3+1). It states "viral culture or an FDA-cleared influenza A and B molecular assay" as confirmation methods for negative results, implying these are the primary methods for ground truth, rather than expert adjudication of the Sofia results themselves.

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 not an AI/CAD-based system designed to assist human readers. It is an in vitro diagnostic (IVD) device that provides automated results (Positive, Negative, Invalid). Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable and was not done. The system reports a direct result, not an interpretation for human review.

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

Yes, the studies conducted demonstrate standalone performance of the Sofia 2 device. The device outputs "Positive, Negative, or Invalid" results based on its internal algorithms and fluorescent signal detection, without human interpretation of the signal. The "Method Comparison" study compares the device's performance against the predicate device using clinical samples, effectively evaluating its standalone accuracy.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc):

The ground truth for defining influenza positive/negative status is indicated implicitly by these statements:

• "A negative test is presumptive and it is recommended these results be confirmed by viral culture or an FDA-cleared influenza A and B molecular assay."
• This suggests that viral culture and/or FDA-cleared molecular assays (which are highly sensitive and specific) were used as the reference standard or "ground truth" to determine the true influenza status of the clinical samples during the performance characteristic studies.

8. The Sample Size for the Training Set:

The document does not specify a sample size for a training set. This type of device (immunofluorescence detection with pre-defined algorithms) typically doesn't involve a "training set" in the machine learning sense. The algorithms are likely developed and validated on internal data during product development, but this information is not provided here. The studies described are primarily for verification and validation against the predicate and established performance characteristics.

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

As mentioned above, a "training set" in the context of machine learning is not applicable here. For the development and initial validation of the device's algorithms, the ground truth would have likely been established using well-characterized samples (e.g., confirmed by viral culture or PCR) to tune the device's sensitivity thresholds for fluorescent signal detection. However, details on this process are not provided in this regulatory submission summary.

Ask a specific question about this device