(80 days)
FilmArray® Respiratory Panel (RP) is a multiplexed nucleic acid test intended for use with the FilmArray Instrument for the simultaneous qualitative detection and identification of multiple respiratory viral and bacterial nucleic acids in nasopharyngeal swabs (NPS) obtained from individuals suspected of respiratory tract infections. The following organism types and subtypes are identified using the FilmArray RP: Adenovirus, Coronavirus 229E, Coronavirus HKU1, Coronavirus NL63, Coronavirus OC43, Human Metapneumovirus, Influenza A, Influenza A subtype H1, Influenza A subtype H3, Influenza A subtype H1-2009, Influenza B, Parainfluenza Virus 1, Parainfluenza Virus 2, Parainfluenza Virus 3, Parainfluenza Virus 4, Human Rhinovirus/Enterovirus, Respiratory Syncytial Virus, Bordetella pertussis, Chlamydophila pneumoniae, and Mycoplasma pneumoniae. The detection and identification of specific viral and bacterial nucleic acids from individuals exhibiting signs and symptoms of a respiratory infection aids in the diagnosis of respiratory infection if used in conjunction with other clinical and epidemiological information. The results of this test should not be used as the sole basis for diagnosis, treatment, or other management decisions. Negative results in the setting of a respiratory illness may be due to infection with pathogens that are not detected by this test or, lower respiratory tract infection that is not detected by a nasopharyngeal swab specimen. Positive results do not rule out co-infection with other organisms: the agent(s) detected by the Film Array RP may not be the definite cause of disease. Additional laboratory testing (e.g. bacterial and viral culture, immunofluorescence, and radiography) may be necessary when evaluating a patient with possible respiratory tract infection.
The FilmArray RP System is a multiplex nucleic acid test system composed of the FilmArray instrument, the FilmArray software (preinstalled on a laptop computer) and the FilmArray RP pouch. The FilmArray RP reagent pouch contains freeze-dried reagents to perform nucleic acid purification, reverse transcription, and nested, multiplex PCR with DNA melt analysis. The RP identifies 20 respiratory pathogens as shown in the following table.
Organisms Detected by the FilmArray Respiratory Panel
A test is initiated by loading Hydration Solution and an unprocessed patient nasopharyngeal swab (NPS) specimen (i.e., specimen mixed with Sample Buffer) into the FilmArray RP pouch. The pouch contains all of the reagents required for specimen testing and analysis in a freeze-dried format; the addition of Hydration Solution and specimen/Sample Buffer Mix rehydrates the reagents. After the pouch is prepared, the FilmArray software guides the user though the steps of placing the pouch into the instrument, scanning the pouch barcode, entering the sample identification, and initiating the run.
The FilmArray instrument contains a coordinated system of inflatable bladders and seal points, which act on the pouch to control the movement of liquid between the pouch blisters. When a bladder is inflated over a reagent blister, it forces liquid from the blister into connecting channels. Alternatively, when a seal is placed over a connecting channel it acts as a valve to open or close a channel. In addition, electronically controlled pneumatic pistons are positioned over multiple plungers in order to deliver the rehydrated reagents into the blisters at the appropriate times. Two Peltier devices control heating and cooling of the pouch to drive the reverse transcription reactions, the PCR reactions, and the melting curve analysis.
Nucleic acid extraction occurs within the FilmArray pouch using mechanical lysis and standard magnetic bead technology. After extracting and purifying nucleic acids from the unprocessed sample, the FilmArray performs a nested multiplex PCR that is executed in two stages. During the first stage, the FilmArray performs a single, large volume, highly multiplexed reverse transcription PCR (rt-PCR) reaction. The products from first stage PCR are then diluted and combined with a fresh, primer-free master mix and a fluorescent double stranded DNA binding dye (LC Green®Plus, BioFire Diagnostics). This second master mix solution; is then distributed to each well of the array. Array wells contain sets of primers designed specifically to amplify sequences internal to the PCR products generated during the first stage PCR reaction. The second stage PCR, or nested PCR, is performed in singleplex fashion in each well of the array. At the conclusion of the 200 stage PCR, the array is interrogated by melting curve analysis for the detection of signature amplicons denoting the presence of specific viral or bacterial targets. A digital camera placed in front of the second stage PCR captures fluorescent images of the PCR reactions in real time.
The FilmArray software automatically interprets the results of each DNA melting curve analysis and combines the data with the results of the internal pouch controls to provide a test result for each organism on the panel.
Here's a summary of the acceptance criteria and the study details for the FilmArray® Respiratory Panel (RP) device, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance (Focusing on Adenovirus, as this is a modification)
The primary acceptance criteria for the modification appear to be improved detection of Adenovirus and equivalent performance for other analytes. Since specific numerical targets for "acceptance criteria" are not explicitly stated in percentages for agreement, the reported performance metrics (PPA and NPA) from the clinical comparison serve as the de facto demonstration of meeting the required performance for regulatory clearance.
| Analyte (Modification Focus) | Acceptance Criteria (Implied) | Reported Device Performance (Modified FilmArray RP vs. Original) |
|---|---|---|
| Adenovirus | Improved detection compared to original panel, especially for C2 and C6 serotypes. LoD of 100 TCID50/mL. | Positive Agreement (Archived Specimens): 100% (15/15) when original detected. |
| Negative Agreement (Archived Specimens): 94.7% (196/207) when original was negative. | ||
| Overall (Archived): Modified detected 26 Adenovirus specimens, original detected 15 (73% greater detection). | ||
| Positive Agreement (Contrived Specimens for C2/C6): n/a (original detected 0, modified detected 20). | ||
| Negative Agreement (Contrived Specimens for C2/C6): 52.3% (23/44). | ||
| LoD: 100 TCID50/mL for AdVC1, AdVC2, AdVE4, AdVC6 (improved from 300 to 3,000,000 for some serotypes in original). Demonstrated 100% detection at LoD. | ||
| Other 19 Analytes | Equivalent performance to the original FilmArray RP. | Generally high positive and negative percent agreements (PPAs and NPAs) ranging from 93.4% to 100%, with narrow 95% Confidence Intervals, suggesting equivalent performance to the original panel. |
2. Sample Size and Data Provenance for the Test Set
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Test Set Sample Size:
- Clinical Comparison (Archived Specimens): 222 de-identified archived nasopharyngeal swab (NPS) specimens.
- Contrived Clinical Specimens: 44 specimens (10 AdVC2, 10 AdVC6, 10 C. pneumoniae, and 14 M. pneumoniae).
- Analytical Sensitivity (LoD): 20 replicates for each of four Adenovirus serotypes (AdVC1, AdVC2, AdVE4, AdVC6) at the estimated LoD.
- Analytical Reactivity (Inclusivity): 22 Adenovirus serotypes (various species) were tested.
- Analytical Specificity (Cross-reactivity/Exclusivity): High concentrations of 20 RP organisms and an exclusivity panel of 26 bacteria, 6 viruses, and 1 yeast.
- Competitive Interference: 5 different virus combinations (co-infections), each tested with two viral components at varying concentrations.
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Data Provenance:
- Archived Specimens: Retrospective, collected between 2008 and 2011 throughout the United States (at least 8 geographically distinct locations) and Scotland (at least 1 location).
- Contrived Clinical Specimens: Spiked NPS specimens.
- Analytical Studies (LoD, Reactivity, Specificity, Interference): Laboratory-generated data using quantified cultures and spiked samples.
3. Number of Experts and Qualifications for Ground Truth of the Test Set
The document does not specify the number or qualifications of experts used to establish the ground truth for the test set.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method for the test set results. The comparison is directly between the original FilmArray RP and the modified FilmArray RP. For discrepant results (e.g., in the archived specimen study), bidirectional sequence analysis was used for confirmation, which serves as a form of "ground truth" establishment for those specific cases, but not a general adjudication process between human readers.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted. This study focuses on "algorithm only" or "device only" performance in comparison to a previous version of the device, not on human reader performance with or without AI assistance.
6. Standalone (Algorithm Only) Performance Study
Yes, a standalone performance study was done. The entire submission details the performance of the modified FilmArray RP (an algorithm-driven diagnostic device) itself, comparing its output to that of the original FilmArray RP and, in discrepant cases or for analytical metrics, to direct molecular confirmation (e.g., sequencing) or known spiked concentrations. There is no human-in-the-loop component described in the performance evaluation.
7. Type of Ground Truth Used
The ground truth for the test samples was established using a combination of methods:
- Original FilmArray RP Results: Performance of the modified device was primarily compared against the results of the previously cleared original FilmArray RP.
- Bidirectional Sequence Analysis: Used to confirm discrepant Adenovirus detections in archived specimens and contrived specimens. Also used to categorize Adenovirus serotypes. This is a highly specific molecular method.
- Known Spiked Concentrations: For contrived specimens and analytical studies (Limit of Detection, Analytical Reactivity, Analytical Specificity, Competitive Interference), the ground truth was the known presence and concentration of the spiked organisms.
8. Sample Size for the Training Set
The document does not specify a sample size for a training set. This is typical for in-vitro diagnostic devices where validation might focus more on analytical performance and clinical concordance rather than a separate "training" of a machine learning algorithm in the same sense as an AI/ML product for image analysis, for example. The "training" of such a system would likely involve extensive internal development and optimization based on known strains and clinical samples, but these are not typically referred to as a "training set" in the context of regulatory submissions unless they are explicitly for an adaptive AI algorithm.
9. How the Ground Truth for the Training Set Was Established
As no specific "training set" is mentioned in the context of the regulatory submission, the method for establishing its ground truth is not described. The device's underlying technology relies on primer design and DNA melt analysis, which are developed and optimized through laboratory experiments rather than a distinct "training set" in the AI/ML sense.
§ 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.