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The Aptima Chlamydia trachomatis (CT) assay is an in vitro qualitative nucleic acid amplification test (NAAT) for the detection of ribosomal RNA (rRNA) from Chlamydia trachomatis to aid in the diagnosis of chlamydia urogenital disease using the Panther System.

The assay may be used to test the following specimens from symptomatic individuals: patient-collected vaginal swab specimens1 (in a clinical setting); and female and male urine specimens.

1 Patient-collected vaginal swab specimens are an option for screening women when a pelvic exam is not otherwise indicated. The Aptima Multitest Swab Specimen Collection Kit has not been evaluated for home use.

The Aptima Chlamydia trachomatis assay (Aptima CT assay) is a target amplification nucleic acid probe test for in vitro qualitative detection of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT). The Aptima CT assay combines the technologies of target capture, transcription-mediated amplification (TMA), and hybridization protection assay (HPA).

Specimens are collected and transferred into their respective specimen transport tubes. The transport solution in these tubes releases the rRNA target and protects it from degradation during storage. When the Aptima CT assay is performed in the laboratory, the target rRNA molecule is isolated from the specimens by use of a capture oligomer via target capture that utilizes magnetic microparticles. The capture oligomer contains a sequence complementary to a specific region of the target molecule as well as a string of deoxyadenosine residues. During the hybridization step, the sequence specific region of the capture oligomer binds to a specific region of the target molecule. The capture oligomer:target complex is then captured out of solution by decreasing the temperature of the reaction to room temperature reduction allows hybridization to occur between the deoxyadenosine region on the capture oligomer and the polydeoxythymidine molecules that are covalently attached to the magnetic particles. The micro particles, including the captured target molecule bound to them, are pulled to the side of the reaction vessel using magnets and the supernatant is aspirated. The particles are washed to remove residual specimen matrix that may contain amplification reaction inhibitors. After the target capture steps are completed, the specimens are ready for amplification.

Target amplification assays are based on the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The Hologic TMA reaction replicates a specific region of the 16S rRNA from CT via DNA intermediates. A unique set of primers is used for the target molecule. Detection of the rRNA amplification product sequences (amplicon) is achieved using nucleic acid hybridization. A single-stranded chemiluminescent DNA probe, which is complementary to a region of the target amplicon, is labeled with an acridinium ester molecule. The labeled DNA probe combines with amplicon to form stable RNA:DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized probe, eliminating the generation of signal from unhybridized probe. During the detection step, light emitted from the labeled RNA:DNA hybrids is measured as photon signals in a luminometer and are reported as Relative Light Units (RLU).

The device reagents are identical to the Aptima CT assay reagents for use on the Tigris DTS® system but are intended for use on the Panther system with different specimen type indications. The Panther and Tigris DTS systems use the same principles of operation.

The provided document is a 510(k) summary for the Aptima Chlamydia trachomatis Assay, which focuses on demonstrating substantial equivalence to a predicate device. It details various analytical and clinical studies conducted to support the performance of the assay on the Panther system.

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

1. A table of acceptance criteria and the reported device performance

The document does not present a single, comprehensive table outlining pre-defined acceptance criteria for each study and then directly reporting the device's performance against those criteria in a tabular format. Instead, acceptance criteria are generally described within the text of each study and the conclusion states whether those criteria were met.

However, based on the descriptions, we can infer some acceptance criteria and the reported performance.

2. Sample size used for the test set and the data provenance

• Clinical Performance Study Test Set Sample Size:
  • Evaluated subjects: 4247 (2283 women, 1964 men).
  • Total specimens analyzed for PIS comparison: 6415 specimens.
    • 2265 patient-collected vaginal swabs
    • 2186 female urine
    • 1964 male urine
• Data Provenance:
  • Country of origin: US (11 geographically and ethnically diverse US clinical sites).
  • Type of study: Prospective, multicenter clinical study.

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

The document states that the Patient Infected Status (PIS) was established by testing specimens with up to 3 FDA-cleared NAATs. It does not explicitly mention the use of human "experts" or their qualifications for establishing the ground truth in the traditional sense of medical image interpretation or pathology review. The ground truth (PIS) for this diagnostic assay is determined by the results of multiple, already-cleared, highly sensitive and specific nucleic acid amplification tests.

4. Adjudication method for the test set

The ground truth (PIS) was established using multiple FDA-cleared NAATs. The method described is:

• Male urine PIS was derived from male urine specimens.
• Female urine PIS was derived from female urine specimens.
• Vaginal swab PIS was derived from vaginal swab and female urine specimens.

This implies a composite reference standard approach (CRS), where the combination of results from multiple established tests determines the "true" infection status. It's not a human expert adjudication method like "2+1" for discordant readings.

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 study was done, and this question is not applicable. The Aptima Chlamydia trachomatis Assay is an in vitro diagnostic (IVD) device, specifically a nucleic acid amplification test (NAAT). It does not involve human readers interpreting images or data where AI assistance would be relevant. The test provides a qualitative result ("detected" or "not detected").

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

This question is also largely not applicable in the context of an IVD NAAT. The "device" (Aptima CT assay on the Panther system) is the standalone algorithm/system. The test is fully automated on the Panther system, providing results without human interpretation of raw signals; humans perform sample loading, system operation, and result review. The analytical and clinical studies described effectively demonstrate its standalone performance.

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

The ground truth used was a composite reference standard (CRS), specifically the Patient Infected Status (PIS) derived from the results of up to 3 FDA-cleared NAATs for each specimen type. This is a common and accepted method for establishing ground truth for IVD assays.

8. The sample size for the training set

The document does not explicitly state a sample size for a "training set." This is typical for an IVD submission focusing on performance characterization for market clearance, rather than an AI/ML device which requires distinct training, validation, and test datasets. The studies described are primarily for validation and verification of the device's performance. The development and optimization of the assay happened prior to these studies, likely using various internal samples, but not separated into a formally reported "training set" like in machine learning contexts.

9. How the ground truth for the training set was established

Since a formal "training set" with separate ground truth establishment is not explicitly mentioned or relevant in the context provided (it's not an AI/ML device), this information is not available in the document. The development of such assays typically involves extensive R&D where assay components, target sequences, and amplification conditions are optimized, but this often doesn't fit the 'ground truth for a training set' paradigm as understood in AI regulation.

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