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The COBAS AMPLICOR™ Chlamydia trachomatis (CT) Test is a qualitative in vitro diagnostic test for the detection of Chlamydia trachomatis in clinical specimens on the COBAS AMPLICOR analyzer. The test utilizes the Polymerase Chain Reaction (PCR) nucleic acid amplification technique and nucleic acid hybridization for the detection of Chlamvdia trachomatis plasmid DNA in endocervical, urethral (male), and urine (male) samples.

The Roche COBAS AMPLICOR™ Chlamydia trachomatis test performed on the COBAS AMPLICOR analyzer is an automated modification of the Roche AMPLICOR Chlamydia trachomatis Microwell Plate Test performed using the Perkin Elmer 9600 thermal cycler and a conventional photometric microwell plate reader (K922906/C). The AMPLICOR™ Chlamydia trachomatis Test was previously shown to be substantially equivalent to tissue culture with immunofluorescent staining for the detection of Chlamydia trachomatis in urogenital swab and male urine The AMPLICOR Chlamydia trachomatis Test has been modified to allow the automation of the samples. amplification and detection test procedure using the COBAS AMPLICOR analyzer. Specimen collection, transport and processing and target amplification with the COBAS AMPLICOR Chlamydia Test are identical to the AMPLICOR Chlamydia Trachomatis Test. COBAS AMPLICOR and microwell AMPLICOR Chlamydia Trachomatis Test detection reagents inentical probes using the appropriate solid support. The clinical and non-clinical performance of the COBAS AMPLICOR Chlamydia Test is substantially equivalent to the AMPLICOR Chlamydia Trachomatis Test.

Here's a breakdown of the acceptance criteria and the study details for the COBAS AMPLICOR Chlamydia Trachomatis Test, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document primarily focuses on demonstrating substantial equivalence to a predicate device rather than setting explicit, numerical acceptance criteria for a new device. However, based on the non-clinical and clinical performance sections, we can infer some criteria and the device's reported performance against them.

• Female Swabs (Culture Positive): COBAS Positive: 19, COBAS Negative: 0 (1 false positive by COBAS, 1 inconclusive by MOMP, 2* by MOMP, 0 false negative by COBAS).
• Male Swabs (Culture Positive): COBAS Positive: 13, COBAS Negative: 0 (0 false positive/negative by COBAS).
• Male Urine (Culture Positive): COBAS Positive: 32, COBAS Negative: 2 (2 false positive by COBAS, 3 false negative by COBAS).
  Note: Detailed sensitivity/specificity calculations are not presented, but the data is presented to show high agreement. |

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

• Non-Clinical (Reproducibility):

  • Test Samples: Swab samples spiked with Chlamydia at four levels (50, 10, 1, 0 IFU/PCR), plus positive and negative kit controls, and six patient samples spanning the reportable range.
  • Replicates: 24 samples per test run, two complete A-tube rings. 27 total replicates for each spiked level and control (implying 3 operators * 3 days * 3 runs, or a similar configuration to achieve 27 total replicates per condition).
  • Data Provenance: Not explicitly stated, but likely from an in-house laboratory setting (Roche Molecular Systems, Inc., Somerville, New Jersey). Retrospective or prospective nature is not specified, but the controlled spiking suggests a prospective experimental design for reproducibility.

• Clinical Performance:

  • Test Set Sample Size: 639 clinical specimens.
    • 266 endocervical swabs (female)
    • 93 male urethral swabs
    • 280 male urine specimens
  • Data Provenance: Not explicitly stated regarding country of origin, but it's clinical data presumably collected for this study or a similar comparative validation. The nature (retrospective/prospective) is not specified, though for a comparative study against a predicate, it could be either.

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

• Non-Clinical (Reproducibility): Ground truth was established by spiking known quantities of Chlamydia organisms (IFU/PCR) into negative samples, or by using known positive/negative controls. No external experts or adjudication for ground truth were explicitly mentioned beyond the device's inherent ability to detect these known quantities. The "operators" performed the tests but did not establish the ground truth itself in this section.

• Clinical Performance: The "ground truth" for the clinical study appears to be defined by a combination of Culture and MOMP (Major Outer Membrane Protein) alternative primer pair testing for the predicate device, which is acting as the reference standard here.

  • The document does not specify the number of experts or their qualifications involved in performing the "Culture" method or "MOMP alternative primer pair testing." These are laboratory techniques, and their accuracy depends on standardized protocols and trained laboratory personnel, rather than expert "adjudication" in the same sense as image interpretation.

4. Adjudication Method for the Test Set

• Non-Clinical (Reproducibility): No adjudication method described; the ground truth was inherently known (spiked samples, kit controls).
• Clinical Performance: No explicit adjudication method is described for discrepancies between the two tests in the clinical performance table in the typical sense of expert review. The table notes "inconclusive results by MOMP alternative primer pair testing" and "COBAS negative on repeat testing," suggesting internal procedures for resolving certain outcomes, but not a formal adjudication by a panel of experts. The comparison is done against the results of the predicate device (AMPLICOR) using culture and MOMP.

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, an MRMC comparative effectiveness study was not done. This device is a molecular diagnostic test (PCR), not an imaging device or AI system that involves human readers interpreting results. Therefore, the concept of "human readers improving with AI vs. without AI assistance" is not applicable here.

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

• The device itself is a standalone diagnostic test kit and automated analyzer system. The "algorithm" here refers to the PCR amplification and hybridization detection process performed by the COBAS AMPLICOR system. The clinical performance study directly evaluates this standalone performance against a predicate device and established diagnostic methods (culture, MOMP). There is no "human-in-the-loop" component for interpretation; the machine provides a qualitative (positive/negative) result.

7. The Type of Ground Truth Used

• Non-Clinical (Reproducibility): Controlled spiking of known quantities of C. trachomatis (IFU/PCR) into negative samples, and commercially prepared positive and negative kit controls.
• Clinical Performance:
  • Culture Positive/Negative: This refers to traditional tissue culture with immunofluorescent staining, which was previously shown to be the reference method for the predicate device.
  • MOMP Positive/Negative: This refers to the use of an alternative primer pair testing for the Major Outer Membrane Protein (MOMP) of C. trachomatis. This is another molecular method used to confirm or resolve certain results, particularly in cases of initial discrepancy or low prevalence.

8. The Sample Size for the Training Set

• The document describes the COBAS AMPLICOR Chlamydia Trachomatis Test as an automated modification of an existing, already validated test (AMPLICOR Chlamydia Trachomatis Microwell Plate Test). It doesn't use a "training set" in the context of machine learning or AI. Instead, the "training" for such a system would involve optimizing the assay parameters (e.g., thermal cycle profile) to achieve equivalent performance.
• The original AMPLICOR Chlamydia Trachomatis Microwell Plate Test itself would have undergone its own development and validation, which would involve experimental optimization. The current submission focuses on demonstrating that the modification (automation) maintains equivalence. Thus, there isn't a "training set" in the common sense for this type of device.

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

• As noted above, there isn't a "training set" in the AI/ML sense. The "ground truth" for the development and optimization of the original AMPLICOR test (which this device is a modification of) would have been established through a combination of:
  • Known bacterial cultures (reference strains and clinical isolates).
  • Clinical samples characterized by established reference methods like tissue culture with immunofluorescent staining.
  • Spiking studies.
  • Analytical characterization (sensitivity, specificity) against other organisms.

The focus of this 510(k) submission is on demonstrating that the new automated platform, while having some modifications, performs equivalently to the already cleared predicate device, which itself was proven substantially equivalent to tissue culture.

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