(213 days)
cobas® HCV is an in vitro nucleic acid amplification test for both the detection and quantitation of hepatitis C virus (HCV) RNA, in human EDTA plasma or serum, of HCV antibody positive or HCV-infected individuals. Specimens containing HCV genotypes 1 to 6 are validated for detection and quantitation in the assay.
cobas® HCV is intended for use as an aid in the diagnosis of HCV infection in the following populations: individuals with antibody evidence of HCV with evidence of liver disease, individuals suspected to be actively infected with HCV antibody evidence, and individuals at risk for HCV infection with antibodies to HCV RNA indicates that the virus is replicating and therefore is evidence of active infection.
cobas® HCV is intended for use as an aid in the management of HCV-infected patients undergoing anti-viral therapy. The assay can be used to measure HCV RNA levels at baseline, during treatment, at the end of treatment, and at the end of follow up of treatment to determine sustained viral response. The results must be interpreted within the context of all relevant clinical and laboratory findings.
cobas® HCV has not been approved for use as a screening test for the presence of HCV in blood or blood products. Assay performance characteristics have been established for individuals treated with certain direct-acting antiviral agents (DAA) regimens. No information is available on the assay's predictive value when other DAA combination therapies are used.
cobas® HCV is a quantitative test performed on the cobas® 5800 System, cobas® 6800 System and cobas® 8800 System. cobas® HCV enables the detection and quantitation of HCV RNA in EDTA plasma or serum of infected patients. Dual probes are used to detect and quantify, but not discriminate genotypes 1–6. The viral load is quantified against a non-HCV armored RNA quantitation standard (RNA-QS), which is introduced into each specimen during sample preparation. The RNA-QS also functions as an internal control to assess substantial failures during the sample preparation and PCR amplification processes. In addition, the test utilizes three external controls: a high titer positive, a low titer positive, and a negative control.
cobas® HCV is based on fully automated sample preparation (nucleic acid extraction and purification) followed by PCR amplification and detection. The cobas® 5800 System is designed as one integrated instrument. 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® 5800 System or cobas® 6800/8800 Systems software(s) which assigns test results for all tests as target not detected, ULoQ (upper limit of quantitation) or HCV RNA detected, a value in the linear range LLoQ ≤ x ≤ ULoQ. Results can be reviewed directly on the system screen, exported, or printed as a report.
Nucleic acid from patient samples, external controls and added armored RNA-QS molecules are simultaneously extracted by addition of proteinase and lysis reagent to the sample. The released nucleic acid binds to the silica surface of the added magnetic glass particles. Unbound substances and impurities, such as denatured protein, cellular debris and potential PCR inhibitors are removed with subsequent wash buffer steps and purified nucleic acid is eluted from the magnetic glass particles with elution buffer at elevated temperature.
Selective amplification of target nucleic acid from the patient sample is achieved by the use of target virus-specific forward and reverse primers which are selected from highly conserved regions of HCV. Selective amplification of RNA-QS is achieved by the use of sequence-specific forward and reverse primers which are selected to have no homology with the HCV genome. A thermostable DNA polymerase enzyme is used for both reverse-transcription and PCR amplification. The target and RNA-QS sequences are amplified simultaneously utilizing a universal PCR amplification profile with predefined temperature steps and number of cycles. The master mix includes deoxyuridine triphosphate (dUTP), instead of deoxythimidine triphosphate (dTTP), which is incorporated into the newly synthesized DNA (amplicon). Any contaminating amplicon from previous PCR runs are eliminated by the AmpErase enzyme, which is included in the PCR mix, during the first thermal cycling step. However, newly formed amplicon are not eliminated since the AmpErase enzyme is inactivated once exposed to temperatures above 55°C.
The cobas® HCV master mix contains dual detection probes specific for the HCV target sequences and one for the RNA-QS. The probes are labeled with target-specific fluorescent reporter dyes allowing simultaneous detection of HCV target and RNA-OS in two different target channels. When not bound to the target sequence, the fluorescent signal of the intact probe is suppressed by a quencher dye. During the PCR amplification step, hybridization of the probes to the specific single-stranded DNA template results in cleavage of the probe by the 5'-to-3' nuclease activity of the DNA polymerase resulting in separation of the reporter and quencher dyes and the generation of a fluorescent signal. With each PCR cycle, increasing amounts of cleaved probes are generated and the cumulative signal of the reporter dye increases concomitantly. Real-time detection and discrimination of PCR products is accomplished by measuring the fluorescence of the released reporter dyes for the viral targets and RNA-QS.
Here's a breakdown of the acceptance criteria and study details for the cobas® HCV device, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are primarily derived from the "Method Comparison" study, which compares the cobas® HCV on the new cobas® 5800 System to the predicate cobas® HCV on the cobas® 6800/8800 Systems.
| Acceptance Criteria (Clinical) | Reported Device Performance (Achieved Results) | Met? |
|---|---|---|
| With all sites combined, 95% of differences in viral load measurement between the cobas® 5800 and cobas® 6800/8800 Systems for positive samples should be less than ±0.5 log10 (viral concentration). | With all sites combined, 100% of differences in viral load measurement between the cobas® 5800 and cobas® 6800/8800 Systems for positive samples were less than ±0.5 log10 (viral concentration). | Yes |
| With all sites combined, 95% of negative sample results should agree between cobas® 5800 and cobas® 6800/8800 Systems. | With all sites combined, 100% of negative sample results agreed between cobas® 5800 and cobas® 6800/8800 Systems based on point estimate of NPA. | Yes |
| Acceptance Criteria (Statistical) | Reported Device Performance (Achieved Results) | Met? |
| With all sites combined, bias estimates at medical decision points should not be statistically significant, i.e., their confidence intervals should include zero. | 25 IU/mL: Bias (95% CI): -0.028 (-0.045, -0.012) | |
| 800,000 IU/mL: Bias (95% CI): 0.027 (0.022, 0.031) | ||
| 6,000,000 IU/mL: Bias (95% CI): 0.037 (0.031, 0.044) | ||
| (Note: Statistically significant, but deemed "not clinically significant") | No | |
| The lower bound of one-sided 95% confidence intervals of the ATD (Agreement in Target Detection) zone percentages should be greater than 90%. | The lower bound of one-sided 95% CI of the ATD zone percentage was 100% for all sites combined and 100% for each site. | Yes |
| The lower bound of the two-sided 95% confidence interval of the NPA (Negative Percent Agreement) should be greater than 90% based on 90 valid test results with 30 negative samples tested at each of the 3 sites. | NPA = 100% with lower bound of 95% CI as 96.667% for all sites combined. | Yes |
Assessment of "No" for Statistical Criteria: The document states that "Although the bias estimates were statistically significant, the differences are not clinically significant given that the biases are well below the standard deviation observed in the Reproducibility Study... and both the upper and lower bound of the 95% Cls are close to zero." This indicates that while the strict statistical criterion was not met, the clinical relevance of the difference was deemed acceptable.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Method Comparison (Test Set):
- HCV positive samples: 150 archived or contrived, well-characterized HCV positive plasma specimens with titers ranging from 1.5E+01 to 1E+08 IU/mL.
- HCV negative samples: 30 individual HCV negative specimens.
- Total: 180 samples.
- Data Provenance:
- The document states "archived or contrived" samples. This indicates a retrospective or laboratory-created dataset.
- The study was conducted at "three different sites (1 internal and 2 external)" for the cobas® 5800 System, and "one site (internal)" for the cobas® 6800/8800 System. The specific country of origin is not explicitly stated, but "Roche Molecular Systems, Inc." is located in Pleasanton, California, USA, implying the study likely took place within the US or involved US-based entities.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify the number or qualifications of experts used to establish the "ground truth" for the test set. It mentions "well-characterized HCV positive plasma specimens" which implies the ground truth was established prior to this study, likely through established clinical diagnostic methods or previous validations. For HCV quantitative assays, gold standards often involve highly calibrated reference methods or known concentrations of viral RNA.
4. Adjudication Method for the Test Set
Not applicable. This device is a quantitative nucleic acid amplification test, and the "ground truth" for its performance is typically based on pre-characterized samples with known concentrations or clinical status, rather than subjective expert consensus and adjudication as might be seen for imaging interpretation. The comparison is between the new system and a predicate system.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No. This study is a method comparison study for an in vitro diagnostic (IVD) device, not an MRMC study for imaging interpretation by human readers. The comparison is between two automated systems (cobas® 5800 and cobas® 6800/8800) for quantifying HCV RNA. Therefore, there is no effect size on how human readers improve with AI vs. without AI assistance.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, essentially. The cobas® HCV assay on both the cobas® 5800 System and the cobas® 6800/8800 System operates as a fully automated, standalone diagnostic device. The performance evaluation presented is algorithm-only (system-only) without a human-in-the-loop component for result generation, although human operators perform the testing. The comparison is the cobas® 5800 system performance versus the cobas® 6800/8800 system performance.
7. The Type of Ground Truth Used
The ground truth for the method comparison study was based on pre-characterized clinical specimens (archived) and contrived samples with known HCV viral loads (titers). This implies a highly controlled and quantitative ground truth, as is typical for molecular diagnostic assays.
8. The Sample Size for the Training Set
The document does not explicitly state the sample size for a "training set." This type of submission (510(k)) is for demonstrating substantial equivalence of a new device (cobas® HCV on cobas® 5800) to a legally marketed predicate device (cobas® HCV on cobas® 6800/8800). The focus is on verification and validation (performance studies) rather than training an AI model from scratch. The cobas® HCV assay itself, as a software-driven assay, would have been developed and optimized using various samples and experiments, but these are not explicitly termed a "training set" in the context of this 510(k) summary.
9. How the Ground Truth for the Training Set Was Established
Given that this is not an AI/ML model for visual interpretation, but rather a molecular diagnostic assay, the concept of "training set ground truth" in the traditional AI sense doesn't directly apply. The "ground truth" for the development and optimization of the assay (which could be analogous to "training") would have involved:
- Known concentrations: Using highly purified and quantified viral RNA standards to establish the linear range, limit of detection, and accuracy.
- Clinical samples with confirmed status: Testing samples from patients confirmed to be HCV positive or negative by established reference methods.
- Spiked samples: Adding known amounts of virus to negative matrices to challenge the assay's performance at specific concentrations.
These steps are part of the standard assay development and validation process for IVD devices, ensuring the assay's chemical and algorithmic components function correctly against known inputs.
§ 866.3170 Nucleic acid-based hepatitis C virus ribonucleic acid tests.
(a)
Identification. A nucleic acid-based hepatitis C virus (HCV) ribonucleic acid (RNA) test is identified as an in vitro diagnostic device intended for prescription use as an aid in the diagnosis of HCV infection in specified populations, and/or as an aid in the management of HCV-infected patients including guiding the selection of genotype-specific treatment in individuals with chronic HCV infection. The test is intended for use with human serum or plasma. The test is not intended for use as a donor screening test for the presence of HCV antibodies in blood, blood products, or tissue donors.(b)
Classification. Class II (special controls). The special controls for this device are:(1) For all nucleic acid-based HCV RNA tests, the labeling required under § 809.10(b) of this chapter must include:
(i) A prominent statement that the test is not intended for use as a donor screening test for the presence of HCV RNA from human cells, tissues, and cellular and tissue-based products.
(ii) A detailed explanation of the principles of operation and procedures for performing the assay.
(iii) A detailed explanation of the interpretation of results.
(iv) Limitations, which must be updated to reflect current clinical practice and disease presentation and management. These limitations must include, but are not limited to, statements that indicate:
(A) The specimen types for which the device has been cleared and that use of this test kit with specimen types other than those specifically cleared for this device may result in inaccurate test results.
(B) When applicable, that assay performance characteristics have not been established in populations of immunocompromised or immunosuppressed patients or, other populations where test performance may be affected.
(C) Test results are to be interpreted by qualified licensed healthcare professionals in conjunction with the individual's clinical presentation, history, and other laboratory results.
(2) For all nucleic acid-based HCV RNA tests, the design verification and validation must include:
(i) Detailed device description, including the device components, ancillary reagents required but not provided, and an explanation of the device methodology. Additional information appropriate to the technology must be included such as design of primers and probes, rationale for the selected gene targets, specifications for amplicon size, and degree of nucleic acid sequence conservation.
(ii) For devices with assay calibrators, the design and nature of all primary, secondary, and subsequent quantitation standards used for calibration as well as their traceability to a standardized reference material that FDA has determined is appropriate (
e.g., a recognized consensus standard). In addition, analytical testing must be performed following the release of a new lot of the standard material that was used for device clearance or approval, or when there is a transition to a new calibration standard.(iii) Documentation and characterization (
e.g., determination of the identity, supplier, purity, and stability) of all critical reagents (including nucleic acid sequences for primers and probes) and protocols for maintaining product integrity.(iv) Detailed documentation of analytical performance studies conducted as appropriate to the technology, specimen types tested, and intended use of the device, including, but not limited to, limit of detection (LoD), upper and lower limits of quantitation (ULoQ and LLoQ, respectively), linearity, precision, endogenous and exogenous interferences, cross reactivity, carryover, matrix equivalency, and sample and reagent stability. Samples selected for use in analytical studies or used to prepare samples for use in analytical studies must be from subjects with clinically relevant circulating genotypes in the United States. Cross-reactivity studies must include samples from HCV RNA negative subjects with other causes of liver disease, including autoimmune hepatitis, alcoholic liver disease, chronic hepatitis B virus, primary biliary cirrhosis, and nonalcoholic steatohepatitis, when applicable. The effect of each claimed nucleic-acid isolation and purification procedure on detection must be evaluated.
(v) Risk analysis and management strategies, such as Failure Modes Effects Analysis and/or Hazard Analysis and Critical Control Points summaries and their impact on test performance.
(vi) Final release criteria to be used for manufactured test lots with appropriate evidence that lots released at the extremes of the specifications will meet the claimed analytical and clinical performance characteristics as well as the stability claims.
(vii) Multisite reproducibility study that includes the testing of three independent production lots.
(viii) All stability protocols, including acceptance criteria.
(ix) Final release test results for each lot used in clinical studies.
(x) Analytical sensitivity and specificity of the test must be the same or better than that of other cleared or approved tests.
(xi) Lot-to-lot precision studies, as appropriate.
(3) For devices intended for the qualitative detection of HCV RNA, in addition to the special controls listed in paragraphs (b)(1) and (2) of this section, the design verification and validation must include detailed documentation of performance from a multisite clinical study. Performance must be analyzed relative to an FDA cleared or approved qualitative HCV RNA test, or a comparator that FDA has determined is appropriate. This study must be conducted using appropriate patient samples, with appropriate numbers of HCV positive and negative samples in applicable risk categories. Additional genotypes must be validated using appropriate numbers and types of samples. The samples may be a combination of fresh and repository samples, sourced from within and outside the United States, as appropriate. The study designs, including number of samples tested, must be sufficient to meet the following criteria:
(i) Clinical sensitivity of the test must have a lower bound of the 95 percent confidence interval of greater than or equal to 95 percent.
(ii) Clinical specificity of the test must have a lower bound of the 95 percent confidence interval of greater than or equal to 96 percent.
(4) For devices intended for the quantitative detection of HCV RNA, the following special controls, in addition to those listed in paragraphs (b)(1) and (2) of this section, apply:
(i) Labeling required under § 809.10(b) of this chapter must include a prominent statement that the test is not intended as a diagnostic test to confirm the presence of active HCV infection, when applicable.
(ii) Design verification and validation must include the following:
(A) Detailed documentation of the following analytical performance studies conducted as appropriate to the technology, specimen types tested, and intended use of the device, including but not limited to: LoD, ULoQ and LLoQ. LoD, LLoQ, and linearity studies must demonstrate acceptable device performance with all HCV genotypes detected by the device.
(B) Detailed documentation of clinical performance testing from either:
(
1 ) A multisite clinical study with an appropriate number of clinical samples from chronically HCV infected patients in which the results are compared to an FDA-cleared or approved quantitative HCV RNA test, or a comparator that FDA has determined is appropriate. This study must include a sufficient number of HCV positive samples containing an analyte concentration near the LLoQ to describe performance at this level. Clinical samples must cover the full range of the device output and must be consistent with the distribution of these genotypes in the U.S. population. Clinical samples may be supplemented with diluted clinical samples for those viral load concentrations that are not sufficiently covered by natural clinical specimens, or(
2 ) A clinical study with prospectively collected samples demonstrating clinical validity of the device.(C) Detailed documentation of a qualitative analysis near the lower end of the measuring range demonstrating acceptable performance when used as an aid in diagnosis.
(5) For devices intended for HCV RNA genotyping, in addition to the special controls listed in paragraphs (b)(1) and (2) of this section, design verification and validation must include the following:
(i) Detailed documentation of an analytical performance study demonstrating the LoD for all HCV genotypes detected by the device.
(ii) Detailed documentation, including results, of a multisite clinical study that assesses genotyping accuracy (
i.e., the proportion of interpretable results that match with the reference method result) and the genotyping rate (i.e., the proportion of results that were interpretable).(6) For any nucleic acid-based HCV RNA test intended for Point of Care (PoC) use, the following special controls, in addition to those listed in paragraphs (b)(1) and (2) of this section, apply:
(i) Clinical studies must be conducted at PoC sites.
(ii) Additional labeling must include a brief summary of the instructions for use that are appropriate for use in a PoC environment.