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The Sofia Strep A+ FIA detects Group A Streptococcal antigens from patients with signs and symptoms of pharyngitis, such as sore throat. All negative test results should be confirmed by either bacterial culture or an FDA-cleared molecular assay because negative results do not prection and should not be used as the sole basis for treatment. The test is intended for professional and laboratory use as an aid in the diagnosis of Group A Streptococcal infection.

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

The Sofia Strep A+ FIA involves the extraction of the antigenic components of the Group A Streptococcus (GAS) bacteria. The patient's Swab sample is placed in the Reagent Tube containing the Reagent Solution, during which time the bacterial antigens are extracted, making them more accessible to the specific antibodies. An aliquot of the extracted sample is dispensed into the Test Cassette sample well. From the sample well, the sample migrates through a test strip containing various unique chemical environments. If Group A Streptococcal antigens are present, they will be bound by antibodies coupled to fluorescent microparticles that migrate through the test strip. The fluorescent microparticles containing bound antigen will be captured by antibodies at a defined location on the test strip where they are detected by Sofia or Sofia 2. If antigens are not present, the fluorescent microparticles will not be trapped by the capture antibodies nor detected by Sofia or Sofia 2.

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 or Sofia 2 will scan the test strip and measure the fluorescent signal by processing the results using method-specific algorithms. Test results will be displayed (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 Sofiea Strep A+ FIA is a device intended to detect Group A Streptococcal antigens from throat swabs of patients with signs and symptoms of pharyngitis. All negative test results must be confirmed by either bacterial culture or an FDA-cleared molecular assay.

As this is a 510(k) submission, the device does not have explicit acceptance criteria mentioned, but rather demonstrates substantial equivalence to a predicate device. The performance data section of the document describes several studies undertaken to document the performance characteristics of the Sofia 2 and the Sofia Strep A+ assay, as well as to compare performance between Sofia and Sofia 2.

Here's the information about the studies presented:

1. Table of Acceptance Criteria and Reported Device Performance:

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

The document does not explicitly state the sample sizes used for each test set in these studies, nor does it specify the country of origin of the data or whether the studies were retrospective or prospective. It refers to "a panel of clinical samples" for the Method Comparison study and "a panel of test samples" for the Reproducibility study.

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

This information is not provided in the document. The nature of the device (antigen detection) likely implies a microbiological gold standard (e.g., bacterial culture), rather than expert consensus on interpretation.

4. Adjudication Method for the Test Set:

This information is not provided in the document.

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

A MRMC comparative effectiveness study involving human readers and AI assistance is not mentioned. The studies focus on the performance of the device itself and its equivalence to a predicate device.

6. Standalone Performance Study:

Yes, standalone performance studies were done. All the studies listed in the "Performance Data" section (LoD, Precision, Assay development time, Method Comparison, Reproducibility) assess the performance of the Sofia Strep A+ FIA on Sofia 2 (and its comparison to Sofia) as a standalone algorithm/device without explicit human-in-the-loop performance measurement.

7. Type of Ground Truth Used:

The document mentions that negative test results "should be confirmed by either bacterial culture or an FDA-cleared molecular assay." This implies that bacterial culture or an FDA-cleared molecular assay would serve as the ground truth for determining the presence or absence of Group A Streptococcal infection in the clinical sample studies.

8. Sample Size for the Training Set:

The document does not provide information about a specific training set or its sample size. This is common for this type of in vitro diagnostic device, where performance is evaluated against known concentrations or clinical samples with confirmed status, rather than training a machine learning model in the conventional sense.

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

As there is no mention of a traditional training set for a machine learning model, the method for establishing ground truth for a training set is not applicable or described in this document. The "ground truth" for the performance evaluation studies would be established using validated methods like bacterial culture or FDA-cleared molecular assays, as mentioned in the indications for use.

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The Sofia Strep A FIA employs immunofluorescence technology to detect Group A Streptococcal antigens from throat swabs of symptomatic patients. All negative test results should be confirmed by bacterial culture because negative results do not preclude Group A Strep infection and should not be used as the sole basis for treatment. The test is intended for professional and laboratory use as an aid in the diagnosis of Group A Streptococcal infection.

The Sofia Strep A FIA employs immunofluorescence technology that is used with the Sofia Analyzer to detect Group A Streptococcal antigens. The Sofia Strep A FIA is a lateral-flow immunoassay that uses polyclonal antibodies that are specific for Group A Streptococcal antigens. Throat swab specimens are used for this test. The patient specimen is placed in the Reagent Tube, during which time the bacteria in the specimen are disrupted, exposing Group A Streptococcal antigens. After disruption, the specimen is dispensed into the cassette sample well. From the sample well, the specimen migrates through a test strip containing various unique chemical environments. If the Group A Streptococcal antigen is present, they will be trapped in a specific location. Note: Depending upon the user's choice, the cassette is either placed inside of the Sofia Analyzer for automatically timed development (Walk Away Mode) or placed on the counter or bench top for a manually timed development and then placed into the Sofia Analyzer to be scanned (Read Now Mode). The Sofia Analyzer will scan the test strip and measure the fluorescent signal by processing the results using method specific algorithms. The Sofia Analyzer will display the test results (Positive, Negative, or Invalid) on the screen. The results can also be automatically printed on an integrated printer if this option is selected.

Here's an analysis of the provided text regarding the acceptance criteria and study for the Sofia® Strep A FIA and Sofia Analyzer:

Note: The provided text lacks the explicit "acceptance criteria" and the full "study that proves the device meets the acceptance criteria" in terms of specific performance targets (e.g., sensitivity, specificity thresholds). It outlines the studies performed and then states a conclusion of "substantial equivalence" based on these studies. Therefore, the table below will present the reported device performance, and the "acceptance criteria" part will reflect an inferred benchmark based on the predicate device and the general aim of demonstrating substantial equivalence.

Acceptance Criteria and Device Performance Study for Sofia® Strep A FIA and Sofia Analyzer

1. Table of Acceptance Criteria and Reported Device Performance

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

• Sample Size for Test Set: The document mentions "A multi-center field clinical study" and "throat swab specimens" for sensitivity and specificity calculations. However, the exact number of specimens or sample size used for the clinical test set is not specified in this summary.
• Data Provenance: The document states "A multi-center field clinical study." The country of origin is not explicitly stated, but being a 510(k) submission to the FDA, it is highly probable that at least a significant portion, if not all, of the clinical data was collected in the United States. The study was prospective, as it was a "field clinical study" to document performance.

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

• The document does not explicitly state the number of experts used to establish the ground truth or their specific qualifications (e.g., "radiologist with 10 years of experience").
• However, for Strep A immunological tests, the ground truth is typically established by bacterial culture, which is considered the gold standard for diagnosis. Therefore, experts involved would likely be clinical microbiologists or laboratory personnel experienced in bacterial culture techniques and interpretation.

4. Adjudication Method for the Test Set

• The document does not specify an adjudication method (e.g., 2+1, 3+1, none) for the test set. Given that the ground truth for Strep A is generally established by bacterial culture, a consensus among human readers for image interpretation (as implied by adjudication in radiology studies) is not typically applicable in this context. The culture result itself serves as the definitive reference.

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, an MRMC comparative effectiveness study was not done as described for AI assistance in image interpretation. This device is an in vitro diagnostic (IVD) test that automates the reading of a lateral-flow immunoassay. It does not involve human readers interpreting images with or without AI assistance in the traditional sense of an MRMC study. The Sofia Analyzer is the "AI" or automated reader, replacing manual visual interpretation.

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

• Yes, a standalone study was done. The Sofia Strep A FIA, when used with the Sofia Analyzer, is designed for automated analysis. The "Read Results" feature states "Read results on instrument screen or print with optional printer" and "Automated Analysis: Yes." The analytical and clinical studies were performed to demonstrate the performance of this automated system directly, without a human-in-the-loop for result interpretation, beyond simply reading the result the analyzer provides.

7. The Type of Ground Truth Used

• The ground truth used for establishing clinical performance (sensitivity and specificity) was bacterial culture. The intended use statement explicitly directs: "All negative test results should be confirmed by bacterial culture because negative results do not preclude Group A Strep infection and should not be used as the sole basis for treatment." This indicates that bacterial culture is the definitive reference method.

8. The Sample Size for the Training Set

• The document does not provide information on the sample size for a training set. For IVD devices like this, the "algorithm" is embedded in the Sofia Analyzer. While the algorithms would have been developed and refined using internal data, this summary focuses on the validation of the final device within clinical and analytical studies, not the development phase.

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

• As with the training set sample size, the document does not provide details on how the ground truth for any potential training set was established. Assuming there was an internal development phase, the ground truth for training data would likely also have been established using bacterial culture as the gold standard, similar to the method for the clinical validation studies.

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