(602 days)
The NucliSens EasyQ® Enterovirus v1.1 Assay is an in vitro nucleic acid amplification assay to be used in conjunction with the NucliSens EasyQ® System for the qualitative detection of Enterovirus RNA in cerebral spinal fluid (CSF) specimens in patients with signs and symptoms of meningitis. This test, in conjunction with other laboratory results and clinical information, may be used as an aid in the presumptive laboratory diagnosis of enterovirus infection in pediatric patients with a clinical suspicion of aseptic meningitis or aseptic meningioencephalitis.
Negative results should be confirmed by cell culture.
Assay performance characteristics have not been established for adults, or for immunocompromised or immunosuppressed patients.
Caution: The results obtained with the NucliSens EasyQ Enterovirus v1.1 Assay should be used only as an adjunct to clinical observation and other information available to the physician. Positive results do not rule out other causes of meningitis, including bacteria, mycobacteria, other viruses (e.g. herpes family viruses, arboviruses, mumps virus, etc) and fungi).
NucliSENS EasyQ® Enterovirus v1.1 is an in-vitro diagnostic assay which uses nucleic acid amplification combined with a simultaneous detection step to detect the presence of enteroviral RNA in eluates derived from cerebrospinal fluid or appropriate control material. The assay requires extracted nucleic acid as input material, and has been validated using nucleic acid eluates extracted from clinical specimens with NucliSENS® miniMAG™. The amplification step is performed using the NucliSENS EasyQ System.
NucliSENS® miniMAG™ utilizes NucliSENS® Lysis Buffer and magnetized silica beads to extract nucleic acids from lysed biological specimens. The end product of a NucliSENS® miniMAG™ extraction is an eluate containing total nucleic acid (DNA+RNA) from the specimen.
The NucliSENS® easyQ™ System utilizes Nucleic Acid Sequence-Based Amplification (NASBA) and detection of fluorescence from specific molecular beacons to signal the presence of target nucleic acid sequences. The NASBA reaction requires the use of specific reagents, including the enzymes, primers and probes which are components of the NucliSENS EasyQ" Enterovirus v1.1 assay. Reactions are performed in closed tubes in a NucliSENS EasyQ® Analyzer in which fluorescence is measured in real-time. NucliSENS EasyQ® Director Software, in combination with NucliSENS EasyQ® Enterovirus v1.1 assav software, provides automated analysis of the resulting fluorescence signal curves and reporting of assay results.
The NucliSENS® easyQ™ System utilizes 3 types of controls: Internal Control RNA, Negative and Positive Controls, and Lysis and Viral Extraction Controls.
This document describes the clinical performance and analytical characteristics of the NucliSens EasyQ® Enterovirus v1.1 Assay.
1. Table of Acceptance Criteria (Implied by Performance) and Reported Device Performance:
| Performance Metric | Acceptance Criteria (Implied by Clinical Context and Device Claim) | Reported Device Performance (Prospectively Collected CSF specimens) | Reported Device Performance (Retrospectively Collected CSF specimens) |
|---|---|---|---|
| Sensitivity (EasyQ vs. Clinical Diagnosis) | High sensitivity for detecting enterovirus infection in pediatric patients with meningitis symptoms. | 80.9% (CI: 74.4 - 86.3%) | 100.0% (CI: 82.4 - 100.0%) |
| Specificity (EasyQ vs. Clinical Diagnosis) | High specificity to minimize false positives. | 99.6% (CI: 97.9 - 99.9%) | 98.1% (CI: 89.7 - 99.9%) |
| Positive Predictive Value (EasyQ with Clinical Diagnosis) | High PPV for a positive result to be truly indicative of infection. | 99.3% (CI: 96.3 - 99.9%) | N/A (not explicitly presented but derivable) |
| Negative Predictive Value (EasyQ with Clinical Diagnosis) | Sufficient NPV to help rule out infection. | 88.3% (CI: 84.1 - 91.7%) | N/A (not explicitly presented but derivable) |
| Positive Agreement (EasyQ and Cell Culture) | Demonstrate good concordance with a recognized method. | 86.4% (CI: 79.3 - 91.7%) | 100.0% (CI: 81.5 - 100.0%) |
| Negative Agreement (EasyQ and Cell Culture) | Demonstrate good concordance with a recognized method. | 89.0% (CI: 85.0 - 92.2%) | 96.2% (CI: 87.0 - 99.5%) |
2. Sample Size and Data Provenance for the Test Set:
- Sample Size:
- Total: 520 pediatric subjects (0 to 21 years of age).
- Prospectively collected: 449 CSF specimens.
- Retrospectively collected: 71 CSF specimens.
- Data Provenance:
- Country of origin: United States. Six clinical sites were located in Ohio, Missouri, Texas (2 sites), Nebraska, and California.
- Retrospective or prospective: Primarily prospective (449/520 specimens) with a minority (71/520 specimens) being retrospectively collected and stored at -70°C.
3. Number of Experts and Qualifications for Ground Truth of the Test Set:
- The document states that the "final diagnosis, as determined by the attending physicians based on signs and symptoms as well as laboratory testing results, was reported to the study investigator."
- Number of experts: Not explicitly stated as a specific number of experts for ground truth establishment. Rather, it refers to the "attending physicians" at the six clinical sites.
- Qualifications of experts: Implied to be medical doctors with expertise in diagnosing meningitis and enterovirus infections based on clinical and laboratory findings. Specific titles or years of experience are not provided.
4. Adjudication Method for the Test Set:
- The ground truth was established by "attending physicians based on signs and symptoms as well as laboratory testing results."
- "Results from the NucliSENS EasyQ® Enterovirus v1.1 were not provided to the attending physicians, and did not influence the final diagnosis." This suggests that the final clinical diagnosis served as the adjudicated ground truth, independent of the device's results. There is no explicit mention of a formal adjudication panel (e.g., 2+1, 3+1).
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No MRMC comparative effectiveness study was done. The study compares the device's performance against clinical diagnosis and cell culture, not against unassisted human readers or AI-assisted human readers.
6. Standalone (Algorithm Only) Performance:
- Yes, the study primarily evaluates the standalone performance of the NucliSENS EasyQ® Enterovirus v1.1 Assay. It describes the assay's detection capabilities for Enterovirus RNA in CSF specimens without human-in-the-loop performance influencing the assay's output. The output of the assay is qualitative (positive/negative).
7. Type of Ground Truth Used:
- Clinical Diagnosis: The primary ground truth for evaluating sensitivity, specificity, and predictive values was the "clinical diagnosis assigned by the attending physicians." This diagnosis was based on clinical observations, other laboratory results (bacteria gram stain, bacteria culture, CSF profile, serum glucose, WBC count, CBC profile), and independent of the NucliSENS EasyQ® Enterovirus v1.1 assay results.
- Cell Culture + IFA: Used as a comparative method alongside clinical diagnosis and as a method to confirm negative results for the device in its intended use statement.
8. Sample Size for the Training Set:
- The document does not explicitly describe a separate "training set" for the assay. This device is an in-vitro diagnostic assay based on NASBA technology, primers, and probes, which are likely designed and validated through laboratory-based analytical studies (e.g., limit of detection, analytical reactivity, specificity, reproducibility) rather than a machine learning training paradigm with a distinct clinical training dataset. The clinical study described served as a validation or test set for the established assay.
9. How Ground Truth for the Training Set Was Established:
- As noted above, a distinct "training set" in the context of machine learning is not described. The analytical studies (LoD, reproducibility, analytical reactivity) used characterized viral strains and controls to establish performance characteristics, rather than a clinical training set with patient outcomes.
§ 866.3225 Enterovirus nucleic acid assay.
(a)
Identification. An enterovirus nucleic acid assay is a device that consists of primers, probes, enzymes, and controls for the amplification and detection of enterovirus ribonucleic acid (RNA) in cerebrospinal fluid (CSF) from individuals who have signs and symptoms consistent with meningitis or meningoencephalitis. The detection of enterovirus RNA, in conjunction with other laboratory tests, aids in the clinical laboratory diagnosis of viral meningitis caused by enterovirus.(b)
Classification. Class II (special controls). The special control is FDA's guidance document entitled “Class II Special Controls Guidance Document: Nucleic Acid Amplification Assay for the Detection of Enterovirus RNA.” See § 866.1(e) for the availability of this guidance document.