(53 days)
The Pro hMPV+ Assay is a Real Time RT-PCR in vitro diagnostic test for the qualitative detection of human Metapneumovirus (hMPV) nucleic acid isolated and purified from nasopharyngeal swab (NP) specimens obtained from individuals exhibiting signs and symptoms of acute respiratory infection. This assay targets a highly conserved region of the Nucleocapsid gene of hMPV. The detection of hMPV nucleic acid from symptomatic patients aids in the diagnosis of human respiratory hMPV infection if used in conjunction with other clinical and laboratory findings. This test is not intended to differentiate the four genetic sub-lineages of hMPV.
Negative results do not preclude hMPV infection and should not be used as the sole basis for diagnosis, treatment or other management decisions.
The Pro hMPV+ Assay enables detection human Metapneumovirus and Internal Control nucleic acid. Nasopharyngeal swab specimens are collected from patients with signs and symptoms of a respiratory infection using a polyester, rayon or nylon tipped swab and placed into viral transport medium.
An Internal Control (IC) is added to each sample prior to nucleic acid isolation to monitor for inhibitors present in the specimens. The isolation and purification of the nucleic acids is performed using either a MagNA Pure LC Instrument (Roche) and the MagNA Pure Total Nucleic Acid Isolation Kit (Roche) or a NucliSENS® easyMAG™ System (bioMérieux) and the Automated Magnetic Extraction Reagents (bioMérieux).
The purified nucleic acids are added to Pro hMPV+ Supermix along with enzymes included in the Pro hMPV+ Assay Kit. The Pro hMPV+ Supermix contains oligonucleotide primers and target-specific oligonucleotide probes. The primers are complementary to highly conserved regions of genetic sequences for these respiratory viruses. The probes are dual-labeled with a reporter dye attached to the 5'-end and a quencher dye attached to the 3'-end.
Reverse transcription of the RNA in the sample into complementary DNA (cDNA) and subsequent amplification of DNA is performed in a Cepheid SmartCycler® II instrument. In this process, the probe anneals specifically to the template followed by primer extension and amplification. The Pro hMPV+ Assay is based on Taqman chemistry, which utilizes the 5' - 3' exonuclease activity of the Taq polymerase to cleave the probe thus separating the reporter dye from the quencher. This generates an increase in fluorescent signal upon excitation from a light source. With each cycle, additional reporter dye molecules are cleaved from their respective probes, further increasing fluorescent signal. The amount of fluorescence at any given cycle is dependent on the amount of amplification products present at that time. Fluorescent intensity is monitored during each PCR cycle by the SmartCyclerII instrument.
Here's an analysis of the acceptance criteria and study detailed in the provided 510(k) summary for the Pro hMPV+ Assay:
Acceptance Criteria and Device Performance for Pro hMPV+ Assay
This summary focuses on the clinical performance of the Pro hMPV+ Assay, which is a Real Time RT-PCR in vitro diagnostic test for the qualitative detection of human Metapneumovirus (hMPV).
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state pre-defined acceptance criteria for the clinical performance metrics (Percent Positive Agreement, Percent Negative Agreement). However, the reported performance is presented with 95% Confidence Intervals, which allows for an assessment of the assay's accuracy. For the purpose of this analysis, we will infer the desired performance to be high agreement with the composite reference methods.
| Metric | Acceptance Criteria (Inferred) | Reported Device Performance (95% CI) | Result |
|---|---|---|---|
| Clinical Performance | |||
| Percent Positive Agreement | High agreement (e.g., >85%) | 94.1% (85.8% - 97.7%) | PASS |
| Percent Negative Agreement | High agreement (e.g., >95%) | 99.3% (98.7% - 99.7%) | PASS |
| Reproducibility | |||
| Overall Percent Agreement with Expected Result (Reproducibility) | High agreement (e.g., >95%) | 99.2% (97.6%-99.7%) | PASS |
2. Sample Size and Data Provenance for the Test Set
- Sample Size: A total of 1275 eligible nasopharyngeal (NP) swab samples were tested and included in the analysis.
- Data Provenance: The study was a prospective study conducted at 4 U.S. clinical laboratories during the 2008 respiratory virus season (January - March). The specimens represented excess NP swab specimens proactively collected from symptomatic individuals suspected of respiratory infection.
3. Number of Experts and Qualifications for Ground Truth Establishment (Test Set)
The ground truth was established using composite reference methods, which involved molecular testing and genetic sequencing, rather than direct expert interpretation of test results. Therefore, the concept of "experts" in the traditional sense (e.g., radiologists) for establishing ground truth doesn't directly apply here.
However, the "experts" involved would be the laboratory personnel performing the molecular (RT-PCR) tests and subsequent genetic sequencing, and those interpreting the sequencing data against the NCBI GenBank database. While no explicit qualifications are given, it can be inferred that these individuals are qualified laboratory professionals experienced in molecular diagnostics and bioinformatics, as they are performing highly specialized and technical analyses for clinical diagnostic purposes.
4. Adjudication Method for the Test Set
The adjudication method for establishing the ground truth was a composite reference standard approach:
- Two independent molecular (RT-PCR) tests for two separate gene targets of hMPV.
- Followed by bidirectional genetic sequencing of those targets.
True hMPV RNA positives were defined as any sample with bidirectional sequencing data meeting pre-defined quality acceptance criteria for one or both gene targets that matched hMPV sequences in the NCBI GenBank database.
True hMPV RNA negatives were defined as any sample tested negative by both comparator methods.
This effectively acts as an internal adjudication process based on multiple, high-specificity molecular methods. There is no mention of a human expert adjudication committee in the traditional sense (e.g., 2+1, 3+1).
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted. This device is an in vitro diagnostic test, not an AI-assisted human reader interpretation tool. Therefore, the concept of measuring how much human readers improve with AI vs. without AI assistance is not applicable.
6. Standalone Performance (Algorithm Only Without Human-in-the-Loop)
Yes, a standalone (algorithm only) performance study was conducted. The "Pro hMPV+ Assay" itself is the algorithm (or diagnostic method) being evaluated. Its performance was assessed directly against the composite reference methods. There is no human-in-the-loop component in its reported diagnostic performance.
7. Type of Ground Truth Used
The type of ground truth used was a composite reference standard based on:
- Molecular diagnostic testing (two independent RT-PCR tests) for different hMPV gene targets.
- Bi-directional genetic sequencing of those targets.
- Comparison of sequencing data to the National Center for Biotechnology Information (NCBI) GenBank database.
This is a highly reliable and objective form of ground truth for viral detection.
8. Sample Size for the Training Set
The document does not provide information regarding a distinct "training set" sample size. For in vitro diagnostic assays like the Pro hMPV+ Assay, the development process typically involves internal validation and optimization studies (which might be analogous to "training"), but specific sample sizes for these internal activities are usually not detailed in 510(k) summaries, which focus on the clinical validation (test set).
9. How the Ground Truth for the Training Set Was Established
As no specific "training set" and its sample size were described, the method for establishing its ground truth is also not provided in this document. During assay development, ground truth for optimization and development samples would typically be established using similar highly sensitive and specific methods (e.g., highly characterized positive and negative controls, sequencing, or alternative validated molecular methods).
§ 866.3980 Respiratory viral panel multiplex nucleic acid assay.
(a)
Identification. A respiratory viral panel multiplex nucleic acid assay is a qualitative in vitro diagnostic device intended to simultaneously detect and identify multiple viral nucleic acids extracted from human respiratory specimens or viral culture. The detection and identification of a specific viral nucleic acid from individuals exhibiting signs and symptoms of respiratory infection aids in the diagnosis of respiratory viral infection when used in conjunction with other clinical and laboratory findings. The device is intended for detection and identification of a combination of the following viruses:(1) Influenza A and Influenza B;
(2) Influenza A subtype H1 and Influenza A subtype H3;
(3) Respiratory Syncytial Virus subtype A and Respiratory Syncytial Virus subtype B;
(4) Parainfluenza 1, Parainfluenza 2, and Parainfluenza 3 virus;
(5) Human Metapneumovirus;
(6) Rhinovirus; and
(7) Adenovirus.
(b)
Classification. Class II (special controls). The special controls are:(1) FDA's guidance document entitled “Class II Special Controls Guidance Document: Respiratory Viral Panel Multiplex Nucleic Acid Assay;”
(2) For a device that detects and identifies Human Metapneumovirus, FDA's guidance document entitled “Class II Special Controls Guidance Document: Testing for Human Metapneumovirus (hMPV) Using Nucleic Acid Assays;” and
(3) For a device that detects and differentiates Influenza A subtype H1 and subtype H3, FDA's guidance document entitled “Class II Special Controls Guidance Document: Testing for Detection and Differentiation of Influenza A Virus Subtypes Using Multiplex Nucleic Acid Assays.” See § 866.1(e) for the availability of these guidance documents.