FilmArray Global Fever Panel

• K Number: DEN200043
• Device Name: FilmArray Global Fever Panel
• Manufacturer: BioFire Defense, LLC
• Date Cleared: 2020-11-20 ( 147 days)
• Product Code: QMV , OMV
• Regulation Number: 866.3966
• Type: Direct
• Panel: MI
• Reference & Predicate Devices: N/A

Intended Use

The FilmArray Global Fever Panel is a qualitative, multiplexed, nucleic acid-based in vitro diagnostic test intended for use with the FilmArray 2.0 system. The FilmArray Global Fever Panel detects and identifies selected bacterial, viral, and protozoan nucleic acids directly from EDTA whole blood collected from individuals with signs and/or symptoms of acute febrile illness or recent acute febrile illness and known or suspected exposure to the following target pathogens: Leptospira spp., chikungunya virus, dengue virus (serotypes 1, 2, 3 and 4), and Plasmodium spp. (including species differentiation of Plasmodium falciparum and Plasmodium vivax/ovale). Evaluation for more common causes of acute febrile illness (e.g., infections of the upper and lower respiratory tract or gastroenteritis, as well as non-infectious causes) should be considered prior to evaluation with this panel. Results are meant to be used in conjunction with other clinical. epidemiologic, and laboratory data, in accordance with the guidelines provided by the relevant public health authorities.

Positive results do not rule out co-infections with pathogens not included on the FilmArray Global Fever Panel. Not all pathogens that cause acute febrile illness are detected by this test, and negative results do not rule out the presence of other infections. Patient travel history and consultation of the CDC Yellow Book should be considered prior to use of the FilmArray Global Fever Panel as some pathogens are more common in certain geographical locations.

Device Description

The FilmArrav Global Fever Panel is a multiplex nucleic acid-based test designed to be used with the FilmArray 2.0 system ("FilmArray system" or "FilmArray instrument"). The FilmArray Global Fever Panel includes a FilmArray Global Fever Panel pouch (pouch) which contains freeze-dried reagents to perform nucleic acid purification and nested, multiplex polymerase chain reaction (PCR) with DNA melt analysis. The FilmArray Global Fever Panel simultaneously conducts six tests for the identification of bacterial, viral, and protozoan organisms from whole blood specimens collected in EDTA tubes. Results from the FilmArray Global Fever Panel are available within about one hour.

A test is initiated by loading Hydration Solution into one port of the pouch and a whole blood or positive blood culture specimen mixed with the provided Sample Buffer and protease into the other port of the pouch and placing it in the FilmArray Instrument. The pouch contains all the reagents required for specimen testing and analysis in a freeze-dried format; the addition of Hydration Solution and the Sample Buffer rehvdrates the reagents. After the pouch is prepared, the FilmArray Software on the FilmArray system guides the user through the steps of placing the pouch into the instrument, scanning the pouch barcode, entering the sample identification, selecting the appropriate protocol, and initiating the run on the FilmArray system.

The FilmArray instruments contain a coordinated system of inflatable bladders and seal points. which act on the pouch to control the movement of liguid 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 PCR reactions and the melt curve analysis.

Nucleic acid extraction occurs within the FilmArray pouch using mechanical and chemical lysis followed by purification using standard magnetic bead technology. After extracting and purifying nucleic acids from the unprocessed sample, a nested multiplex PCR is executed in two stages. During the first stage, a single, large volume, highly multiplexed reverse transcription PCR (rt-PCR) reaction is performed. 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 Defense, LLC). The 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 2nd stage PCR, or nested PCR, is performed in each well of the array. At the conclusion of the 2nd stage PCR, the array is interrogated by melt curve analysis for the detection of signature amplicons denoting the presence of specific targets. A digital camera placed in front of the array captures fluorescent images of the PCR2 reactions and software interprets the data.

The FilmArray software automatically interprets the results of each DNA melt 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.

AI/ML Overview

Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are generally demonstrated through the successful performance in the analytical and clinical studies. While explicit "acceptance criteria" are not listed in a separate table, the reported performance metrics (PPA, NPA, agreement rates) indicate the achieved levels that were deemed acceptable.

Metric / Criterion	Acceptance Criteria (Implied by Study Design & FDA Review)	Reported Device Performance (Summary)
Analytical Performance
Reproducibility	High agreement with expected results across sites, operators, and lots; low variability in melt temperature (SD 1x LoD.	Most isolates detected within >1x LoD. Limitations noted for P. falciparum (SenTh021.09, 10x LoD), Dengue virus (Serotype 3 BC188/97, Serotype 4 D85-019, ~100x LoD), and Dengue virus (Serotype 2 DKA 811, Not Detected).
Microbial Interference	No interference with pouch controls or specific assay targets by other microorganisms.	No interference observed for 10 tested microorganisms.
Analytical Specificity/Cross-reactivity	No non-specific amplification or detection by off-panel organisms; limited and identified cross-reactivity for on-panel near-neighbors.	Detected cross-reactivity: P. knowlesi with P. vivax/ovale assay (>2.2E+03 copies/mL). P. brasilianum (identical to P. malariae) showed reactivity with P. vivax/ovale assay (undisclosed copies/mL). No other cross-reactivity observed in wet testing. No expected cross-reactivity by in silico analysis.
Interfering Substances	No interference effect from endogenous, exogenous, or technique-specific substances/anticoagulants.	No interference observed for most tested substances. Potential interference from TRIzol (initial, then not reproducible) and Heparin (initial, then improved reproducibility, but still potentially inhibitory near LoD).
Specimen Stability	Consistent detection (e.g., 10/10 replicates positive) across recommended storage conditions (room temp, refrigerated, ultra-low freezer) and consistency between fresh vs. frozen.	All analytes: 10/10 replicates positive for all evaluated storage conditions. Fresh vs. Frozen Contrived Specimens: PPA 100% for all organisms. NPA 100% for all organisms. Fresh vs. Frozen Clinical Specimens: PPA 100% for all organisms. NPA 100% for Leptospira, Dengue, Chikungunya, Plasmodium spp. P. falciparum NPA 97.1%, P. vivax/ovale NPA 97.0%.
Clinical Performance
Positive Percent Agreement (PPA)	High agreement with comparator method (implied by accepted results).	Overall (Fresh & Frozen): Chikungunya 100%, Dengue 94.0%, Leptospira 93.8%, Plasmodium spp. 98.3%, P. falciparum 92.7%, P. vivax/ovale 92.7%.
Negative Percent Agreement (NPA)	High agreement with comparator method (implied by accepted results).	Overall (Fresh & Frozen): Chikungunya 99.9%, Dengue 100%, Leptospira 99.8%, Plasmodium spp. 99.2%, P. falciparum 99.8%, P. vivax/ovale 100%.

Study Design and Proof of Meeting Acceptance Criteria:

The detailed performance characteristics section (L. Performance Characteristics) outlines the studies conducted to demonstrate the device meets these criteria. The approval of the De Novo request signifies that the FDA found these results acceptable and the device adequately characterized for its intended use, with appropriate mitigations for identified risks.

2. Sample Sizes and Data Provenance

• Test Set (Clinical Study):

  • Total Eligible Specimens: 1875 whole blood specimens.
  • Category I (Prospective, Fresh): 1469 (78.3%) specimens.
  • Category II (Prospective, Frozen): 406 (21.7%) specimens.
  • Data Provenance: Multicenter study conducted at ten geographically distinct study sites, including two in the United States, and sites in Africa, Southeast Asia, and Central & South America. Data was collected prospectively (March 2018 - September 2019).

• Analytical Studies (Reproducibility, LoD, etc.): Sample sizes for these studies are distinct and smaller than the clinical study.

  • Reproducibility: 270 valid test results (90 replicates per sample, 3 samples, 3 sites, 5 days, 2 operators, 3 instruments, rotating pouch lots).
  • Detection Limit: "m replicates" tested for confirmation, and "x replicates" initially. Specific numerical values are redacted.
  • Inclusivity/Cross-reactivity/Interference: "replicates" (number often redacted) of spiked samples.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number or specific qualifications of experts used to establish the ground truth for the clinical test set.

• Clinical Study Ground Truth: The ground truth for the clinical samples was established using "well-validated nested PCR assays followed by bi-directional Sanger sequencing."

  • "Two comparator assays were utilized for each assay target with positive result from both assays considered positive."
  • "If the results of the two comparator assays for a particular analyte disagreed, the samples were subjected to repeat comparator testing with samples determined as positive if at least 2/3 replicates were positive for a single comparator assay."
  • This implies a laboratory-based method for ground truth, rather than human expert consensus on clinical presentation.

• Assay Cut-off Validation (post-analytical/clinical studies): "a final validation of the melt ranges was performed and included review of data from the Inclusivity study and clinical studies. The observed sensitivity and specificity rates for the individual melt curves and assay calls as compared to expert annotation was greater than 99.8% and 99.9% respectively."

  • This indicates that "expert annotation" was used to validate the final melt ranges of the software's interpretation of results, suggesting these experts were likely highly specialized in nucleic acid analysis or molecular diagnostics. Specific number or qualifications are not provided beyond "expert annotation."

4. Adjudication Method for the Test Set

• The primary method for establishing ground truth for the clinical test set was through two comparator nested PCR assays followed by Sanger sequencing.
• Discrepancy Resolution/Adjudication: "Samples for which false positive and/or false negative results (i.e., discrepant results) were obtained when comparing the FilmArray Global Fever Panel results to the comparator method results were further investigated."
  • This investigation typically involved:
    1. Examination to determine if additional testing on Global Fever Panel or with comparator assays could detect the analyte (if near or below detection threshold).
    2. Evaluation by "at least one additional PCR test that used different primers than the Global Fever Panel assay or the comparator assays."
    3. When possible, "unresolved discrepancies were evaluated with additional PCR testing that could be verified by sequence analysis."
  • This describes a multi-step, laboratory-based adjudication process for discrepant results, leveraging additional molecular methods. It is not a 2+1 or 3+1 human reader adjudication, but rather a technical/laboratory adjudication.

5. Multi Reader Multi Case (MRMC) Comparative Effectiveness Study

• No, an MRMC comparative effectiveness study was not performed.
• This device is an in vitro diagnostic (IVD) nucleic acid amplification test, and its performance is evaluated against a molecular gold standard (comparator PCR and sequencing), not through human reader interpretation of images or other data. Therefore, the concept of "how much human readers improve with AI vs without AI assistance" does not apply here.

6. Standalone Performance

• Yes, the performance characteristics described in Section L (Performance Characteristics) represent the standalone performance of the FilmArray Global Fever Panel algorithm and system. This includes analytical performance (reproducibility, LoD, specificity, etc.) and the clinical performance (PPA, NPA) which compares the device's output directly to the "ground truth" established by the comparator molecular methods. The system automatically interprets the results of each DNA melt curve analysis and combines data with internal controls to provide a test result.

7. Type of Ground Truth Used

• For the clinical study, the primary ground truth was established by molecular comparator testing: "well-validated nested PCR assays followed by bi-directional Sanger sequencing." This is a highly objective, laboratory-based method for detecting and identifying specific nucleic acid sequences.

8. Sample Size for the Training Set

• The document does not explicitly state the sample size for a "training set".
• This is a molecular diagnostic assay where algorithms (e.g., for melt curve analysis) are likely developed based on known principles of PCR and fluorescence, and validated with a range of characterized samples (analytical studies). There isn't a traditional "training set" in the context of deep learning models for medical image analysis, which require large datasets for supervised learning. Instead, the "initial melt ranges" were determined by "mathematical modeling using known sequence variations... as well as data from testing of clinical specimens and known isolates."

9. How the Ground Truth for the Training Set Was Established

• As a molecular diagnostic, the "training" (or development/refinement) data for the device's interpretive algorithm (e.g., Melt Detector software Tm values, fluorescence values, and melt curve analysis) would primarily come from:
  • Well-characterized isolates and contrived samples: Used to define expected melt curves, Tm values, and limits of detection. This includes the extensive analytical studies detailed (e.g., inclusivity, cross-reactivity, precision, LoD).
  • Mathematical modeling: Based on known sequence variations of target organisms.
  • Data from clinical specimens: Likely used to fine-tune and validate the interpretive algorithm (as indicated by the "final validation of the melt ranges" including "review of data from the Inclusivity study and clinical studies" against "expert annotation"). This implies that known positive and negative samples, rigorously characterized by molecular methods (and potentially expert review for complex cases), would inform the algorithm's development.

Regulation Number and Section

§ 866.3966 Device to detect and identify selected microbial agents that cause acute febrile illness.

(a)
Identification. A device to detect and identify selected microbial agents that cause acute febrile illness is identified as an in vitro device intended for the detection and identification of microbial agents in human clinical specimens from patients with signs and symptoms of acute febrile illness who are at risk for exposure or who may have been exposed to these agents. It is intended to aid in the diagnosis of acute febrile illness in conjunction with other clinical, epidemiologic, and laboratory data, including patient travel, pathogen endemicity, or other risk factors.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Any sample collection device used must be FDA-cleared, -approved, or -classified as 510(k) exempt (standalone or as part of a test system) for the collection of specimen types claimed by this device; alternatively, the sample collection device must be cleared in a premarket submission as a part of this device.
(2) The labeling required under § 809.10(b) of this chapter must include:
(i) An intended use that includes a detailed description of targets the device detects and measures, the results provided to the user, the clinical indications appropriate for test use, and the specific population(s) for which the device is intended.
(ii) Limiting statements indicating:
(A) Not all pathogens that cause febrile illness are detected by this test and negative results do not rule out the presence of other infections;
(B) Evaluation of more common causes of acute febrile illness should be considered prior to evaluation with this test;
(C) Test results are to be interpreted in conjunction with other clinical, epidemiologic, and laboratory data available to the clinician; and
(D) When using this test, consider patient travel history and exposure risk, as some pathogens are more common in certain geographical locations.
(iii) A detailed device description, including reagents, instruments, ancillary materials, all control elements, and a detailed explanation of the methodology, including all pre-analytical methods for processing of specimens.
(iv) Detailed discussion of the performance characteristics of the device for all claimed specimen types as shown by the analytical and clinical studies required under paragraphs (b)(3)(ii) and (iii) of this section, except specimen stability performance characteristics.
(v) A statement that nationally notifiable results are to be reported to public health authorities in accordance with local, state, and federal law.
(3) Design verification and validation must include:
(i) A detailed device description (
e.g., all device parts, control elements incorporated into the test procedure, reagents required but not provided, the principle of device operation and test methodology), and the computational path from collected raw data to reported result (e.g., how collected raw signals are converted into a reported result).(ii) Detailed documentation of analytical studies, including those demonstrating Limit of Detection (LoD), inclusivity, cross-reactivity, microbial interference, interfering substances, competitive inhibition, carryover/cross contamination, specimen stability, within lab precision, and reproducibility, as appropriate.
(iii) Detailed documentation and performance results from a clinical study that includes prospective (sequentially collected) samples for each claimed specimen type and, when determined to be appropriate by FDA, additional characterized clinical samples. The study must be performed on a study population consistent with the intended use population and compare the device performance to results obtained from FDA-accepted comparator methods. Documentation from the clinical studies must include the clinical study protocol (including a predefined statistical analysis plan), study report, testing results, and results of all statistical analyses.
(iv) A detailed description of the impact of any software, including software applications and hardware-based devices that incorporate software, on the device's functions.