(102 days)
The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza B, and RSV viral infections in humans and is not intended to detect influenza C.
Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.
Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 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 the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.
Simplexa™ Flu A/B & RSV Positive Control Pack REF MOL2660
Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the SimplexaTM Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.
The Simplexa™ Flu A/B & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, detection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.
In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.
The provided text describes a 510(k) summary for the Simplexa™ Flu A/B & RSV Direct and Simplexa™ Flu A/B & RSV Positive Control Pack. This submission is intended to add eight additional influenza strains to the analytical reactivity of the device and addresses modifications made to the device from an earlier version (K120413).
Here's a breakdown of the requested information based on the document:
1. Table of acceptance criteria and the reported device performance
The document does not explicitly state "acceptance criteria" in the format of pass/fail thresholds for clinical performance. Instead, it presents "Positive Percent Agreement (PPA)" and "Negative Percent Agreement (NPA)" with a predicate device (Gen 1.0) and between device versions (Gen 2.0 and Gen 2.1) as part of method comparison studies, along with analytical reactivity and specificity data.
Method Comparison Results (Performance in relation to K120413 and between versions)
| Target | Comparison | Metric | Reported Device Performance (Gen 2.0 vs Gen 1.0) | 95% CI (Gen 2.0 vs Gen 1.0) | Reported Device Performance (Gen 2.1 vs Gen 2.0) | 95% CI (Gen 2.1 vs Gen 2.0) |
|---|---|---|---|---|---|---|
| Flu A | PPA | Gen 2.0 vs Gen 1.0 | 100.0% (58/58) | 93.0% to 100.0% | - | - |
| NPA | Gen 2.0 vs Gen 1.0 | 95.7% (198/207) | 91.9% to 97.7% | - | - | |
| PPA | Gen 2.1 vs Gen 2.0 | - | - | 100.0% (58/58) | 93.8% to 100.0% | |
| NPA | Gen 2.1 vs Gen 2.0 | - | - | 99.0% (205/207) | 96.5% to 99.7% | |
| Flu B | PPA | Gen 2.0 vs Gen 1.0 | 98.2% (54/55) | 90.4% to 99.7% | - | - |
| NPA | Gen 2.0 vs Gen 1.0 | 95.7% (201/210) | 92.1% to 97.7% | - | - | |
| PPA | Gen 2.1 vs Gen 2.0 | - | - | 100.0% (56/56) | 93.6% to 100.0% | |
| NPA | Gen 2.1 vs Gen 2.0 | - | - | 100.0% (209/209) | 98.2% to 100.0% | |
| RSV | PPA | Gen 2.0 vs Gen 1.0 | 97.8% (45/46) | 88.7% to 99.6% | - | - |
| NPA | Gen 2.0 vs Gen 1.0 | 95.9% (210/219) | 92.4% to 97.8% | - | - | |
| PPA | Gen 2.1 vs Gen 2.0 | - | - | 100.0% (55/55) | 93.5% to 100.0% | |
| NPA | Gen 2.1 vs Gen 2.0 | - | - | 100.0% (210/210) | 98.2% to 100.0% |
Analytical Reactivity (Gen 2.1): All tested influenza A, influenza B, and RSV strains at specified concentrations were detected (100% detection for all, assayed in triplicate). These include:
- 18 Influenza A strains (H1, H3, H7N9)
- 10 Influenza B strains
- 4 RSV strains (A and B)
Cross Reactivity (Analytical Specificity) (Gen 2.1): No cross-reactivity was observed with 32 tested organisms (bacteria and other viruses) at clinically relevant concentrations. All results showed 0% detection for Flu A, Flu B, and RSV, and 100% detection for the Internal Control.
Interference (Gen 2.1): No evidence of interference was observed from potentially interfering substances (e.g., nasal sprays, antiviral drugs, blood, mucin protein) tested in contrived samples. All showed 100% detection for Flu A, Flu B, RSV, and RNA IC.
Limit of Detection (LoD) (Gen 2.1): The LoD for various strains across Gen 1.0, Gen 2.0, and Gen 2.1 are provided (e.g., Influenza A/Hong Kong/8/68 (H3N2) Gen 2.1 LoD: 0.1 TCID50/mL). The criteria for LoD determination was ≥95.0% detection (at least 31/32 replicates).
Precision (Gen 2.1): High reproducibility (low %CV) was observed for Ct values across inter-day, inter-run, inter-lot, and intra-run/lot variations for low and moderate positive samples of Flu A, Flu B, and RSV, as well as positive and negative controls. Qualitatively, all expected positive samples were detected at 100%, and negative samples were not detected for the target analytes.
2. Sample size used for the test set and the data provenance
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Sample Size (Method Comparison): For each comparison (Gen 1.0 vs Gen 2.0, and Gen 2.0 vs Gen 2.1), 265 archived clinical samples were used.
- Composition: 55 positive for influenza A, 55 positive for influenza B, 55 positive for RSV, and 100 negative for all tested viruses.
- Data Provenance: The samples were "archived clinical samples" in Universal Transport Medium (UTM) or Viral Transport Medium (VTM).
- 131 of these samples for the Gen 1.0 vs Gen 2.0 comparison were originally tested in support of K120413. The remaining 134 included 33 from the 2010-2011 flu season and 101 from the 2013-2014 flu season.
- For the Gen 2.0 vs Gen 2.1 comparison, 125 samples were from K120413 study. The remaining 140 included 48 from the 2010-2011 flu season, 9 from 2012-2013, and 83 from 2013-2014.
- The country of origin is not specified, but the context implies data likely from the USA (given FDA submission). The data is retrospective as it uses archived samples.
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Sample Size (Analytical Reactivity/Cross Reactivity/Interference):
- Analytical Reactivity: Each viral strain was assayed in triplicate.
- Cross Reactivity: Each organism was tested in triplicate (3 replicates). Baseline negative matrix was tested in five (5) replicates.
- Interference: Each interfering substance was tested in triplicate (3 replicates). Baseline was tested in 15 replicates.
- Limit of Detection: Initially, 4 concentrations per virus tested in triplicate. Confirmatory testing involved 32 replicates for the lowest concentration.
- Precision: Each sample panel member tested in duplicate for each Reaction Mix lot in each run, two runs per day for a total of three days, yielding at least 36 replicates per panel member (41 for one Flu B sample).
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
The document does not explicitly state the use of "experts" to establish ground truth for the test set in the method comparison studies. The ground truth for these studies appears to be based on results from the predicate device (Simplexa™ Flu A/B & RSV Direct Gen 1.0) and/or other FDA cleared Nucleic Acid Tests (NATs) for discrepant samples. For analytical studies (reactivity, cross-reactivity, interference, LoD, precision), the ground truth is established by the known concentration/presence of the spiked organisms or substances.
4. Adjudication method for the test set
For the method comparison studies, discrepancies between the modified device (Gen 2.0 or Gen 2.1) and the predicate device (Gen 1.0 or Gen 2.0 respectively) were sometimes resolved using another FDA cleared NAT. For example, for Flu A discrepancies in the Gen 1.0 vs Gen 2.0 comparison, "7/9 discrepant (K120413 – Negative and K142365 – Positive) samples were positive for Flu A on another FDA cleared NAT." This suggests a form of adjudication using a third, independent, cleared method.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
This section is not applicable. The device described is an in vitro diagnostic (IVD) assay for the detection of viruses using real-time RT-PCR, not an AI-powered diagnostic imaging device involving human readers or interpretation of medical images. Therefore, MRMC studies and the concept of human reader improvement with AI assistance do not apply.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done
This concept is not directly applicable in the context of an IVD assay like the Simplexa™ Flu A/B & RSV Direct. The device is essentially a "standalone" algorithm/assay from the perspective of direct human interpretation providing a qualitative result (detected/not detected). The performance metrics (PPA, NPA, analytical reactivity, LoD, etc.) represent the standalone performance of the assay system. There is no human "in the loop" for interpreting the raw assay output; the instrument's software interprets the Ct values to provide a qualitative result.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Clinical Studies (Method Comparison): The ground truth for the clinical sample comparisons was based on:
- The performance of the predicate device (Simplexa™ Flu A/B & RSV Direct Gen 1.0) for direct comparison between versions.
- Other FDA cleared Nucleic Acid Tests (NATs) for resolving discrepant results between the device versions.
- Analytical Studies (Reactivity, Cross-Reactivity, Interference, LoD, Precision): The ground truth was established by known spiked concentrations of characterized viral strains, bacterial organisms, or potentially interfering substances into negative matrix.
8. The sample size for the training set
The document does not explicitly mention a "training set" in the context of machine learning or AI models, as this is an IVD assay. The development and optimization ("changes to the reaction mix formulation and cycling conditions," "changes to the manufacturing process and materials") that led to Gen 2.0 and Gen 2.1 would have involved internal validation and optimization data, which could be considered analogous to training data in a broad sense for assay development. However, specific "training set sizes" are not provided.
9. How the ground truth for the training set was established
As described in point 8, a formal "training set" for an AI model is not applicable here. For the assay development and optimization, ground truth would have been established through controlled laboratory experiments using well-characterized viral isolates and defined concentrations, analogous to how ground truth for the analytical studies (reactivity, LoD) was established.
§ 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.