Search Results

The cobas® SARS-CoV-2 Nucleic acid test for use on the cobas® SARS-CoV-2) is an automated, realtime reverse transcriptase polymerase chain reaction (RT-PCR) test intended for the rapid in vitro qualitative detection of nucleic acid from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in anterior nasal (nasal) and nasopharyngeal swab specimens collected from individuals with signs and symptoms of respiratory tract infection (i.e., symptomatic). Additionally, this test is intended to be used with nasal and necimens collected from individuals without signs and symptoms suspected of COVID-19 (i.e., asymptomatic).

The cobas® SARS-CoV-2 performed on the cobas® Liat® System is intended for use as an aid in the diagnosis of COVID-19 if used in conjunction with other clinical, epidemiologic, and laboratory findings. SARS-CoV-2 RNA is generally detectable in nasal and nasopharyngeal swab specimens during the acute phase of infection.

Positive results are indicative of the presence of SARS-CoV-2 RNA. Positive results do not rule out co-infection with other microorganisms.

A negative result from an asymptomatic individual is presumptive. Additionally, a negative result obtained with a nasal swab collected from an asymptomatic patient should be followed up by testing at least twice over three days with at least 48 hours between tests.

Negative results do not preclude SARS-CoV-2 infection.

The results of this test should not be used as the sole basis for diagnosis, treatment management decisions.

This test is intended for prescription use only and can be used in Point-of-Care settings.

The cobas® SARS-CoV-2 Nucleic acid test for use on the cobas® Liat® System (cobas® SARS-CoV-2) uses real-time reverse transcriptase polymerase chain reaction (RT-PCR) technology to rapidly (approximately 20 minutes) detect SARS-CoV-2 virus from nasopharyngeal and nasal swabs. The automation, small footprint, and easy-to-use interface of the cobas® Liat® System enable performance of this test to occur at the POC or in a clinical laboratory setting.

The cobas® SARS-CoV-2 assay is performed on the cobas® Liat® Analyzer which automates and integrates sample purification, nucleic acid amplification, and detection of the target sequence in biological samples using real-time RT-PCR assays. The assay targets both the ORF1 a/b nonstructural region and nucleocapsid protein gene that are unique to SARS-CoV-2. An Internal Process Control (IPC) is also included. The IPC is present to control for adequate processing of the target virus through steps of sample purification, nucleic acid amplification, and to monitor the presence of inhibitors in the RT-PCR processes.

Here's an analysis of the acceptance criteria and study findings for the "cobas SARS-CoV-2 Nucleic acid test for use on the cobas Liat System" based on the provided text:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the clinical performance evaluation results, specifically the Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with a composite comparator method. While explicit acceptance criteria values are not stated (e.g., "PPA must be >X%"), the device's performance is presented to demonstrate its effectiveness.

Study Information

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

   • Clinical Performance Evaluation (Test Set):
     • Evaluable NPS samples: 1874 (fresh and frozen)
       • Symptomatic: 673 NPS
       • Asymptomatic: 1201 NPS (413 suspected, 788 no suspicion)
     • Evaluable NS samples: 1872 (fresh and frozen, including 1 indeterminate result)
       • Symptomatic: 674 NS
       • Asymptomatic: 1198 NS (411 suspected, 787 no suspicion)
     • Frozen Samples (included in above totals): 23 positive and 23 negative NPS specimens, and 23 positive and 23 negative NS specimens.
     • Data Provenance: Prospectively collected clinical specimens from February-June 2022 (fresh samples) and earlier during the COVID-19 pandemic (March-June 2021) for frozen samples. The document does not specify the country of origin, but it implies collection within "10 point-of-care healthcare facilities" without further geographic detail.

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

   • The ground truth for the test set was established using a composite comparator method consisting of "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays."
   • The document does not specify the number or qualifications of human experts involved in establishing this ground truth. The ground truth relies on the performance of these reference RT-PCR assays.

3. Adjudication method for the test set:

   • The text describes a "composite comparator method" using "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays." This implies a form of consensus or a predefined algorithm for combining the results of these three assays to establish the definitive positive or negative status. However, the specific adjudication rules (e.g., "2 out of 3 positive for overall positive") are not explicitly described.

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 MRMC comparative effectiveness study involving human readers or AI assistance is described. This study focuses on the standalone performance of the cobas SARS-CoV-2 test.

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

   • Yes, a standalone performance study was done. The entire clinical performance evaluation section (Section 7) describes the performance of the "cobas SARS-CoV-2 test" (the device/algorithm) against a composite comparator method (ground truth) without human intervention in the result interpretation of the device. The device itself is an automated RT-PCR test.

6. The type of ground truth used:

   • The ground truth used was a composite comparator method based on the results from "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays." This is a form of laboratory reference standard.

7. The sample size for the training set:

   • The document describes a clinical performance evaluation (test set) and analytical studies. It does not provide information about the sample size of a specific "training set" for the device, as it is a molecular diagnostic test rather than a machine learning algorithm that typically undergoes explicit training on large datasets in the way an AI image analysis product would. The development (implied "training" in a broader sense for assay optimization) would have used various samples, but these are not explicitly detailed as a distinct training set in the provided text.

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

   • As no explicit "training set" with established ground truth is described in the context of typical AI/ML development, this question cannot be answered from the provided text. The assay development would involve extensive analytical validation using characterized viral samples and clinical specimens validated by reference methods, which broadly contribute to optimizing the assay's performance.

Ask a specific question about this device