(212 days)
The cobas® Cdiff Nucleic acid test for use on the cobas® Liat® System is an automated, qualitative in vitro diagnostic test that uses real-time polymerase chain reaction (PCR) for the detection of the toxin B (tcdB) gene of toxigenic Clostridioides difficile (C.difficile) in unformed (liquid or soft) stool specimens obtained from patients suspected of having C. difficile infection (CDI). The cobas® Cdiff Nucleic acid test for use on the cobas® Liat® System is intended for use as an aid in the diagnosis of CDI in humans in conjunction with clinical and epidemiological risk factors.
The cobas® Cdiff Nucleic Acid Test for use on the cobas® Liat® System (cobas® Cdiff) is a rapid, automated in vitro diagnostic test for qualitative detection and differentiation of C. difficile DNA in human stool specimens. The cobas® Liat® is for in vitro diagnostic use. The system is designed to identify and/or measure presence of genetic material in a biological sample. The system automates all nucleic acid amplification test (NAAT) processes, including reagent preparation, target enrichment, inhibitor removal, nucleic acid extraction, amplification, real-time detection, and result interpretation in a rapid manner. The cobas® Cdiff test uses silica magnetic particle-based nucleic acid extraction and TaqMan probe-based real-time PCR amplification and detection. The cobas® Liat® Analyzer automates and integrates sample purification, nucleic acid amplification and detection of the target sequence in biological samples. Other than adding the sample to the cobas® Cdiff assay tube, no reagent preparation or additional steps are required. The cobas® Cdiff assay tube that holds all of the sample purification and PCR reagents and hosts the sample preparation and PCR process specific for the Cdiff analyte. The test uses the assay tube as both the sample and reaction vessel. The assay tube comprises flexible tubing containing all required unit dose reagents pre-packed in tube segments, separated by pressure-sensitive seals, in the order of reagent use. During the testing process, multiple sample processing actuators of the analyzer compress the cobas® Cdiff assay tube to selectively release reagents from tube segments, move the sample from one segment to another, and control reaction conditions such as reaction volume, temperature, pressure, and incubation time. Precise control of all these parameters provides optimal conditions for assay reactions, allowing the test to achieve high performance similar to or better than that of currently available molecular assays. The cobas® Liat® Analyzer software controls and coordinates these actions to perform all required assay processes, including sample preparation, nucleic acid extraction, target enrichment, inhibitor removal, nucleic acid elution, and real-time PCR. All assay steps are performed within the closed and self-contained cobas® Cdiff assay tube, thereby eliminating the potential for cross-contamination between samples. The collected data are automatically analyzed and the result is displayed in the assay report on the integrated LCD touch screen of the cobas® Liat® Analyzer.
The provided text is a 510(k) summary for the cobas® Cdiff Nucleic Acid Test for use on the cobas® Liat® System. The purpose of this submission is to demonstrate substantial equivalence to a previously cleared device (K171770), specifically addressing a software update (Liat® Analyzer Software 3.3).
Therefore, the primary study discussed is a performance evaluation to demonstrate that the software update does not negatively impact the device's performance, thereby maintaining substantial equivalence to the predicate device.
Here's a breakdown of the requested information based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of "acceptance criteria" with numerically reported performance metrics for sensitivity, specificity, accuracy, etc., as typically seen in initial device clearance studies. Instead, it states that the performance of the modified device was evaluated and that the overall cobas® Cdiff assay performance and claims were not impacted by the software changes. This implies that the acceptance criterion was essentially "no significant change in performance" compared to the predicate device, which had already met its own performance criteria.
| Acceptance Criterion (Implied) | Reported Device Performance |
|---|---|
| No significant impact on overall cobas® Cdiff assay performance | "The result of this evaluation determined that the overall cobas® Cdiff assay performance and claims were not impacted by changes implemented in cobas® Liat® Analyzer Software 3.3, when compared to the current commercially available core software version." |
| Continued substantial equivalence to predicate device (K171770) | "Equivalent performance of the modified device and the current commercial device has been demonstrated, and analytical or clinical performance has not changed. The modified device is substantially equivalent to the predicate device, as cleared through K171770." |
2. Sample Size Used for the Test Set and Data Provenance
The document does not provide details on the sample size or data provenance (e.g., country of origin, retrospective/prospective) for the performance evaluation related to the software update. It only discusses the evaluation of the software's impact on the assay. The original predicate device clearance (K171770) would contain this information for the initial performance claims.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This information is not provided in the context of this software update evaluation. The ground truth for the test set of the original device was likely established during its initial clearance (K171770), and this document focuses on confirming that the software change doesn't alter that established performance.
4. Adjudication Method for the Test Set
This information is not provided in this document.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, an MRMC comparative effectiveness study is not applicable here. This device is an automated in vitro diagnostic test (nucleic acid amplification test), not an imaging device or a system that involves human readers interpreting results in a comparative effectiveness study setting. The device is designed to provide a qualitative result (detection of the toxin B gene).
6. If a Standalone Study (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, implicitly. The evaluation focuses on the performance of the cobas® Cdiff assay with the updated software on the cobas® Liat® System. This is a standalone performance assessment of the automated diagnostic device (algorithm and hardware combined) without human interpretation impacting the primary result itself. The result is "automatically analyzed and...displayed" (page 5).
7. The Type of Ground Truth Used
The document does not explicitly state the type of ground truth used for this specific software update evaluation. For the initial clearance of a diagnostic test like this, ground truth for clinical performance studies would typically involve:
- Culture confirmation (e.g., toxigenic C. difficile culture)
- An FDA-cleared reference method or composite reference method (CRM) utilizing multiple tests and/or expert clinical judgment.
This document assumes that the established ground truth methodology for the predicate device remains valid and that the software update does not affect the device's ability to correlate with that ground truth.
8. The Sample Size for the Training Set
The document does not provide information on the sample size for the training set for the software (algorithm) itself. Given that this is a software update for an already cleared diagnostic system, "training set" in the context of machine learning (if applicable for some internal functions) is not detailed. The test uses established PCR principles and validated oligonucleotide sequences.
9. How the Ground Truth for the Training Set was Established
This information is not provided and is likely not relevant as this is an update to an analytical testing platform rather than a de novo AI/ML algorithm requiring a specific "training set" with ground truth in the traditional sense. The assay's core principles (oligonucleotide sequences, PCR) are described as unchanged from the predicate, which would have undergone its own rigorous analytical and clinical validation.
§ 866.3130 Clostridium difficile toxin gene amplification assay.
(a)
Identification. AClostridium difficile toxin gene amplification assay is a device that consists of reagents for the amplification and detection of target sequences inClostridium difficile toxin genes in fecal specimens from patients suspected of havingClostridium difficile infection (CDI). The detection of clostridial toxin genes, in conjunction with other laboratory tests, aids in the clinical laboratory diagnosis of CDI caused byClostridium difficile. (b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Toxin Gene Amplification Assays for the Detection ofClostridium difficile; Guideline for Industry and Food and Drug Administration Staff.” See § 866.1(e) for information on obtaining this document.