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The First To Know Syphilis Test is a qualitative rapid membrane immunochromatographic assay for the detection of Treponema pallidum (syphilis) antibodies in human whole blood (capillary). This test is intended for over the counter (OTC) consumer use in individuals suspected of syphilis. Positive test results with the First To Know Syphilis Test alone are not sufficient to diagnose syphilis infection and must be followed by additional laboratory testing through a health care provider to confirm a diagnosis of syphilis.

This test is not a substitute for visits to a healthcare provider. The information provided by this product should not be used to start, stop or change any treatments without a healthcare provider.

Results of testing with the First To Know Syphilis Test will likely be positive for individuals previously diagnosed with syphilis, even if they were successfully treated. The First To Know Syphilis Test cannot determine whether there has been re-infection with syphilis.

The First To Know Syphilis Test is a single-use, lateral-flow, visually-read test that is intended for over-the-counter use by lay persons. All components of the test are contained in the cassette; no additional reagents are required to run the test. Procedure controls are intrinsic to the cassette. A single [~40 uL] drop of human capillary whole blood is added to the cassette. No software or instrumentation is required for use of the test. There are no accessories required to use the test. The test is a chromatographic immunoassay that delivers results in 15 minutes.

Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:

Acceptance Criteria and Device Performance for First To Know Syphilis Test

Please note: The document does not explicitly list "acceptance criteria" in a separate section with pass/fail thresholds. Instead, it describes various performance studies and their outcomes. The table below infers acceptance criteria based on the reported performance and the overall conclusion of the De Novo request.

Study Details:

For Clinical Performance (Comparison Studies C.1. Method Comparison and C.3. Clinical Studies):

1. Sample size used for the test set and the data provenance:

   • Total enrolled participants: 1424
   • Evaluable specimens: 1379 (after exclusions for incomplete paperwork, withdrawal, screening/blood draw failures)
   • Final evaluable First To Know Syphilis Test results with paired valid comparator results: 1270 (after further exclusions for invalid comparator results, laboratory errors, and device invalid results)
   • Data provenance: Prospective study enrolling individuals at six geographically diverse clinical sites in the U.S., conducted from September 2021 through October 2023.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • The ground truth was established by "comparator testing using two separate treponemal tests and one non-treponemal test."
   • Experts: The document does not specify the number or qualifications of the individuals who performed or interpreted these comparator tests (e.g., laboratory technicians, pathologists, infectious disease specialists). It refers to a "Comparator Algorithm Positive" where the positive comparator result was determined by at least two reactive results from these tests.

3. Adjudication method (e.g., 2+1, 3+1, none) for the test set:

   • The adjudication method for establishing the ground truth was based on a "comparator algorithm" defined as "at least two reactive results" from the three comparator tests (two treponemal, one non-treponemal). This suggests an agreement-based method, effectively a "2 out of 3" rule.

4. 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, an MRMC comparative effectiveness study was not done. This device is a visually-read, lateral-flow immunoassay intended for over-the-counter (OTC) consumer use by lay persons, without AI assistance. The performance reported is for the device as a standalone OTC test.

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

   • Yes, the primary clinical performance (PPA and NPA) reflects standalone performance in the hands of lay users. While site observers were present to assess ease of use, they "did not aid the lay users in performing the test." Therefore, the reported PPA and NPA represent the device's performance as interpreted by the intended end-user without professional human clinical interpretation or assistance beyond the device's labeling.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • The ground truth was established through reference laboratory testing (a "comparator algorithm") using a combination of two treponemal tests and one non-treponemal test, with a positive result requiring at least two reactive outcomes. This is a common and accepted method for serological diagnoses like syphilis. For the "Staged Syphilis Testing," characterized serum samples from known positive Syphilis patients clinically diagnosed at various stages were used, implying a clinical diagnosis as part of that specific ground truth.

7. The sample size for the training set:

   • The document describes optimization of the assay cut-off during development but does not specify a distinct "training set" size in the context of machine learning or AI. For assay optimization to establish the cut-off, it states: "Twenty individual samples were prepared for the C5 and C95 levels and tested using three lots of the First To Know Syphilis Test providing 60 individual data points for each concentration." This refers to specific concentrations (C5, C95) for assay development rather than a broad training set for an algorithm.

8. How the ground truth for the training set was established:

   • For the assay cut-off optimization, "known positive samples prepared from serum specimens obtained from clinically-positive individuals" were used. These samples were diluted to "levels that corresponded to a negative, high-non reactive (C5), low reactive (C95), and moderate reactive (2x C95) concentration as determined by an FDA-cleared total Syphilis IgG/IgM assay." This indicates that an existing, FDA-cleared laboratory assay served as the ground truth reference for defining the concentrations used in optimizing the First To Know Syphilis Test's cut-off.

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