(40 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 nucleic acids in nasopharyngeal swabs (NPS) obtained from individuals suspected of respiratory tract infections. The following virus types and subtypes are identified using the FilmArray RP: Adenovirus, Coronavirus HKU1, Coronavirus NL63, Human Metapneumovirus, Influenza A, Influenza A subtype H1, Influenza A subtype H3, Influenza A subtype 2009 H1, Influenza B, Parainfluenza Virus 1, Parainfluenza Virus 2, Parainfluenza Virus 3, Parainfluenza Virus 4, Rhinovirus/Enterovirus, and Respiratory Syncytial Virus. The detection and identification of specific viral nucleic acids from individuals exhibiting signs and symptoms of a respiratory infection aids in the diagnosis of respiratory viral infection if used in conjunction with other clinical and epidemiological information. Negative results do not preclude respiratory viral infection and should not be used as the sole basis for diagnosis, treatment or other management decisions. Positive results do not rule out bacterial infection or co-infection with other organisms. The agent detected may not be the definite cause of disease. The use of additional laboratory testing (e.g. bacterial and viral culture, immunofluorescence, and radiography) and clinical presentation must be taken into consideration in order to obtain the final diagnosis of respiratory infection.
Due to seasonal prevalence, performance characteristics for Influenza A/H1, Influenza A/H3, Influenza A/2009 H1, Influenza B, Parainfluenza Virus 1, Parainfluenza Virus 2, and Parainfluenza Virus 4 were established primarily with retrospective clinical specimens.
Due to the genetic similarity between human Rhinovirus and Enterovirus, the FilmArray RP cannot reliably differentiate them. A positive FilmArray RP Rhinovirus/Enterovirus result should be followed-up using an alternate method (e.g. cell culture or sequence analysis).
The FilmArray RP detects Adenovirus species C serotype 2 and serotype 6 with reduced sensitivity. It is recommended that specimens found to be negative for Adenovirus after examination using FilmArray RP be confirmed by an alternate method (e.g. FDA cleared molecular test or cell culture).
Performance characteristics for influenza A were established when influenza A/2009 H1N1, A/H1, and A/H3 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary. If infection with a novel influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to state or local health departments for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.
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 pouch contains freeze-dried reagents to perform nucleic acid purification, reverse transcription, and nested, multiplex PCR with DNA melt analysis. The Respiratory Panel (RP) pouch identifies 15 common and emerging viral respiratory pathogens (see Table 1).
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 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 dve (LC Green@Plus, Idaho Technology). 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 breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:
Device: FilmArray Respiratory Panel (RP) System
Purpose of 510(k) submission: To support unmasking of test results for the Parainfluenza Virus 1, 2, and 4 (PIV1, PIV2, PIV4) assays in the FilmArray RP.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are generally implied standards for diagnostic tests (e.g., high sensitivity and specificity). The reported device performance is directly from the study results.
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance (PIV1, PIV2, PIV4) - Clinical Study | Reported Device Performance (PIV1, PIV2, PIV4) - Archived Specimens |
|---|---|---|---|
| Clinical Sensitivity (PPA) | High (>85-90%) | PIV1: 100% (1/1) | PIV1: 97.1% (34/35) |
| PIV2: 87.4% (7/8) | PIV2: 100% (28/28) | ||
| PIV4: 100% (9/9) | PIV4: 100% (11/11) | ||
| Clinical Specificity (NPA) | High (>90-95%) | PIV1: 99.9% (1115/1116) | PIV1: 100.0% (94/94) |
| PIV2: 99.8% (1107/1109) | PIV2: 100.0% (101/101) | ||
| PIV4: 99.9% (1107/1108) | PIV4: 100.0% (6/6) | ||
| Limit of Detection (LoD) | Consistent detection (≥95%) at specified concentration | PIV1: 500 TCID50/mL | Not applicable |
| PIV2: 10 TCID50/mL | Not applicable | ||
| PIV4: 5000 TCID50/mL | Not applicable | ||
| Analytical Reactivity (Inclusivity) | Detection of diverse strains at or near LoD | All tested PIV1, PIV2, PIV4 strains detected at 1x LoD. | Not applicable |
| Analytical Specificity (Cross-reactivity/Exclusivity) | No cross-reactivity with common/related organisms | No cross-reactivity observed with tested organisms (Table 13, 14, 15), except for Adenovirus in one Measles virus stock. | Not applicable |
| Precision (Reproducibility) | High agreement with expected results across sites and runs | PIV1 (Med/Low Pos): 98.3%-100% agreement. PIV2/PIV4 (Med/Low Pos): 100% agreement. (See Tables 16, 17, 18) | Not applicable |
| Precision (Repeatability) | High agreement with expected results in-house | PIV1: 97.9%-100% (Mod/Low Pos); PIV2: 97.9%-100% (Mod/Low Pos); PIV4: 100% (Mod/Low Pos). (Table 19) | Not applicable |
| Interference | No significant interference from common substances | None of the tested endogenous/exogenous substances found to interfere. | Not applicable |
2. Sample Size Used for the Test Set and Data Provenance
Clinical Performance Study (Prospective):
- Sample Size: 1117 subjects (after exclusions) from an initial enrollment of 1144.
- Data Provenance: Prospective study conducted at 3 U.S. clinical sites. Enrollment spanned December 2009 - May 2010 and September 2010 - January 2011 (two respiratory seasons).
Archived Specimens Study (Retrospective):
- Sample Size: 147 confirmed specimens tested (from 168 initially selected).
- Data Provenance: Retrospective study using preselected archived clinical nasopharyngeal swab (NPS) specimens. The origin of these archived samples is not specified beyond being "preselected" and from "one source" (a pediatric hospital mentioned for age range).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The term "experts" in the context of diagnostic assay ground truth typically refers to reference laboratory personnel or clinicians involved in the gold standard method. The document describes the methods used to establish ground truth rather than explicitly stating the number and qualifications of individuals.
For Parainfluenza Virus 1 and 2 (Clinical Study):
- Ground Truth Method: Viral culture followed by DFA (Direct Fluorescent Antibody) identification.
- Implicit Expertise: Laboratory technicians/virologists skilled in viral culture techniques and DFA interpretation. No specific number or qualifications (e.g., years of experience) mentioned.
For Parainfluenza Virus 4 (Clinical Study):
- Ground Truth Method: Viral culture followed by one analytically validated PCR assay with bi-directional sequence confirmation.
- Implicit Expertise: Laboratory technicians/virologists skilled in viral culture, PCR amplification, and sequence analysis. No specific number or qualifications mentioned.
For Archived Specimens Study:
- Ground Truth Method: Analyte-specific PCR and bi-directional sequencing.
- Implicit Expertise: Laboratory personnel proficient in molecular diagnostic techniques and sequence analysis. No specific number or qualifications mentioned.
4. Adjudication Method for the Test Set
The document does not explicitly describe an "adjudication method" in the typical sense of multiple experts reviewing discordant results. Instead, it describes how "true" positive/negative status was determined based on the outcomes of the reference methods:
- Clinical Study (PIV1, PIV2, PIV4):
- For PIV1 and PIV2, "True" positives/negatives were defined by the viral culture with DFA results.
- For PIV4, "True" positives were defined by bi-directional sequencing data matching NCBI GenBank sequences from viral culture material. "True" negatives were defined by negative results from the comparator PCR assay on viral culture material.
- Discrepancies between the FilmArray RP and comparator methods were sometimes further investigated (e.g., PIV1 was identified in one discordant specimen by bi-directional sequence analysis; PIV2 in false positive specimens by bi-directional sequencing). This suggests a form of post-hoc review for discrepant results, but not a front-end adjudication process by multiple independent experts defining ground truth prior to or independent of the reference method.
- Archived Specimens Study: Ground truth was established by "analyte specific PCR and bi-directional sequencing" prior to FilmArray RP testing. The study design meant users testing with FilmArray RP were "blinded as to the expected test result." This indicates the ground truth was predetermined by molecular methods.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed. This study focuses on the diagnostic performance of the device itself against reference methods, not on comparing human reader performance with and without AI assistance. The FilmArray RP is an automated diagnostic system, not an AI-assisted interpretation tool for human readers.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) was done
Yes, the study describes the standalone performance of the FilmArray RP System.
- The FilmArray RP is a fully automated system from specimen loading to result interpretation. 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."
- The clinical sensitivity, specificity, and analytical studies (LoD, inclusivity, specificity, precision, interference) all evaluate the performance of this automated system directly against established reference methods or controlled conditions, without human interpretation as part of the primary diagnostic output.
7. The Type of Ground Truth Used
- Clinical Performance Study:
- Expert Consensus: Not explicitly stated as consensus among multiple experts. The ground truth was established by viral culture followed by DFA (PIV1, PIV2) and viral culture followed by analytically validated PCR with bi-directional sequence confirmation (PIV4). These are established laboratory diagnostic methods often considered gold standards for viral detection at the time.
- Pathology: Not applicable, as this is a viral detection assay, not tissue pathology.
- Outcomes Data: Not primarily outcomes data, but a direct comparison to laboratory reference methods for pathogen presence.
- Archived Specimens Study:
- Molecular Confirmation: Ground truth was established using analyte-specific PCR and bi-directional sequencing. This is a highly specific molecular method for confirming the presence or absence of viral nucleic acid.
8. The Sample Size for the Training Set
The document does not specify a training set size because it describes a diagnostic device validation study, not a machine learning model development study with separate training and testing sets. The FilmArray RP is a molecular diagnostic assay using pre-programmed algorithms for interpretation, not a learnable AI algorithm that requires a "training set" in the machine learning sense. The device's internal algorithms and reagents are developed, and then validated with the clinical and analytical performance studies described.
9. How the Ground Truth for the Training Set Was Established
As noted above, there is no "training set" in the context of machine learning for this device. The device's operational parameters and interpretive logic are presumably established during its development phase using a combination of scientific principles, laboratory experiments, and internal validation, rather than through labeled training data as used in AI.
§ 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.