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The cobas® CT/NG on the cobas® 6800/8800 system is an automated, qualitative in vitro nucleic acid diagnostic test, that utilizes real-time polymerase chain reaction (PCR), for the direct detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA in male and female urine, clinician-instructed self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas® PCR Media (Roche Molecular Systems, Inc.), and cervical specimens collected in PreservCyt® solution. This test is intended as an aid in the diagnosis of chlamydial and gonococcal disease in both symptomatic and asymptomatic individuals.

cobas® CT/NG is a new qualitative test performed on the cobas® 6800 System and cobas® 8800 System. cobas® CT/NG enables the detection of CT/NG DNA in endocervical, vaginal, urine and cervical specimens of infected female patients and urine specimens in infected male patients. Target-specific primers and two probes are used to detect but not discriminate between the CT cryptic plasmid and the ompA gene. Additionally, target-specific primers and two probes are used to detect but not discriminate between two conserved sequences in the NG DR-9 region. The DNA Internal Control, used to monitor the entire sample preparation and PCR amplification process, is introduced into each specimen during sample processing. In addition, the test utilizes a low titer positive and a negative control. cobas® CT/NG is based on fully automated sample preparation (nucleic acid extraction and purification) followed by PCR amplification and detection. The cobas® 6800/8800 Systems consist of the sample supply module, the transfer module, the processing module, and the analytic module. Automated data management is performed by the cobas® 6800/8800 software which assigns test results for all tests as positive, negative or invalid. Results can be reviewed directly on the system screen, exported, or printed as a report.

Here's a breakdown of the acceptance criteria and study information for the cobas® CT/NG for use on the cobas® 6800/8800 Systems device, extracted from the provided text:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the clinical performance and reproducibility study results. The device aims for high sensitivity, specificity, and reproducibility.

Table of Acceptance Criteria and Reported Device Performance

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

Clinical Performance Study:

• Total Subjects Enrolled: 5,197
• Eligible Subjects: 5,105
• Evaluable Subjects (Prospective): 5,053 (3,860 females, 1,193 males)
• Archived Specimens (Female): 371 urogenital samples from 295 female subjects (used for NG detection). These originated from a previous clinical study for cobas® CT/NG v2 test on the cobas® 4800 System.
• Total Samples Tested (across both CT & NG analyses, including prospective and archived): 17,169

Data Provenance:

• Geographic Origin: 9 geographically diverse sites in the US.
• Retrospective/Prospective: Primarily prospective data collection. Some female NG archived specimens were used, which were "archived prospectively collected" from a previous study.

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

The ground truth was established using a Patient Infected Status (PIS) algorithm, which relied on the results of multiple FDA-cleared NAATs (Nucleic Acid Amplification Tests) rather than human expert interpretation of images or clinical findings directly.

• Number of "Experts" (for constructing ground truth):
  • For females: A combination of results from 2 commercially available FDA-cleared NAATs.
  • For males: A combination of results from 3 commercially available FDA-cleared NAATs.
• Qualifications of "Experts": The "experts" in this context are the FDA-cleared NAATs themselves, which are established diagnostic tests for CT/NG. The text does not mention human experts delineating ground truth for individual cases.

4. Adjudication Method for the Test Set

The adjudication method was a Patient Infected Status (PIS) algorithm based on the concordance of results from multiple FDA-cleared NAATs.

• For females:
  • Infected: One or more positive results in each of the two NAATs. A scenario where one NAAT is positive/negative and the other is positive/positive also leads to "Infected".
  • Not Infected: Varied combinations of negative results or discordant results between the two NAATs, where the majority are negative.
  • Indeterminate: If one or more sample types are invalid for the NAATs, or if there are discordant results with invalid/missing data, the PIS is indeterminate.
• For males:
  • Infected/Not Infected: At least 2 out of the 3 test results must be concordant positive or negative, respectively.
  • Indeterminate: If one test result is invalid/missing and the other two are discordant, or if 2 or 3 test results are invalid/missing, the PIS is indeterminate.

This method essentially acts as a "majority vote" or expert consensus (of diagnostic tests) ground truth.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not explicitly performed or described in the provided text. This study focuses on the diagnostic accuracy of the device compared to a composite reference standard (PIS), not on how human readers' performance might improve with the AI (an in vitro diagnostic device) as an aid.

Effect Size: N/A (since an MRMC study was not described)

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

Yes, the study describes the standalone performance of the cobas® CT/NG system. The device is referred to as an "automated, qualitative in vitro nucleic acid diagnostic test" that uses real-time PCR. It directly detects CT/NG DNA, and the system software "assigns test results for all tests as positive, negative or invalid." This clearly indicates an algorithm-only standalone performance evaluation.

7. The Type of Ground Truth Used

The type of ground truth used was a composite reference standard known as Patient Infected Status (PIS).

• This PIS was determined by a combination of results from multiple FDA-cleared NAATs.
• Therefore, the ground truth is based on a consensus of highly accurate molecular diagnostic tests, which is a form of expert consensus (where the "experts" are established diagnostic technologies). It is not based on pathology reports, simple expert visual review, or patient outcomes data directly.

8. The Sample Size for the Training Set

The document does not provide information regarding a specific "training set" sample size. This is typical for a diagnostic device undergoing FDA clearance, where the focus is on validation against an independent test set rather than reporting on the development (training) phase of an AI or algorithm. The device is a PCR-based test, which generally involves laboratory optimization and locked-down algorithms rather than iterative machine learning training sets in the same way an image-based AI would.

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

As no specific training set and its associated ground truth establishment were described in this document, this information is not available / not applicable based on the provided text.

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