(238 days)
Focus Diagnostics' Plexus™ EBV IgG Multi-Analyte Diagnostics test kit is intended for qualitatively detecting the presence or absence of human IgG class antibodies to viral capsid antigen (VCA), early antigen- diffuse (EA-D), and nuclear antigen (EBNA-1) of Epstein-Barr virus in human sera. The test is indicated as an aid in the diagnosis of EBV infection and EBV-associated infectious mononucleosis.
The performance of this assay has not been established for use in the diagnosis of nasopharyngeal carcinoma and Burkit's lymphoma, for testing of immunocompromised patients, for use by a point of care facility or for use with automated equipment. This assay has not been evaluated for donor screening.
Multiplexed Immunoassay for the Qualitative Detection of Human IgG Antibodies to Epstein-Barr Virus
The Focus Diagnostics Plexus™ EBV IgG uses an Antigen Bead suspension that contains three distinct EBV antigen bead types (EA-D, VCA, & EBNA-1) and one process control bead type that fluoresce at different wavelengths and/or intensities.
The Focus Diagnostics Plexus™ EBV IgG is a three step procedure,
- Patient sera are diluted, and the diluted sera are incubated with Antigen Beads. If EBV antibodies are present, then the antibodies bind to the corresponding antigen beads.
- Phycoerythrin-conjugated goat Anti-human IgG (Conjugate) is added, binds to the bound EBV antibody (if present), and forms a Conjugate-EBV antibody-antigen bead sandwich.
- Fluorescence from each distinct EBV antigen bead type is measured and compared against a Cutoff Calibrator.
Here's an analysis of the provided text regarding the acceptance criteria and study for the Plexus EBV IgG Multi-Analyte Diagnostics device:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state pre-defined acceptance criteria in terms of specific percentages for agreement. Instead, it presents the "Positive Percent Agreement" for different serological statuses when compared against predicate devices. While not an explicit acceptance criterion, the percentage agreement values indicate the device's performance relative to the established ground truth.
| Performance Metric | Acceptance Criteria (Implicit from Study Design) | Reported Device Performance (vs. Predicate) |
|---|---|---|
| EBV VCA IgG (Prospective) | High positive percent agreement across serological statuses | |
| Primary Acute (Positive) | N/A (implied high agreement) | 100% (57/57), 95% CI: 93.7-100% |
| Late Acute (Positive) | N/A (implied high agreement) | 97.2% (70/72), 95% CI: 90.4-99.2% |
| Recovering (Positive) | N/A (implied high agreement) | 100% (1/1), 95% CI: 20.7-100% |
| Previous Infection (Positive) | N/A (implied high agreement) | 96.6% (282/292), 95% CI: 93.8-98.1% |
| No Infection (Negative) | N/A (implied high agreement) | 93.5% (203/217), 95% CI: 89.5-96.1% |
| Indeterminate (Positive) | N/A (implied high agreement) | 98% (49/50), 95% CI: 89.5-99.6% |
| Indeterminate (Negative) | N/A (implied high agreement) | 100% (15/15), 95% CI: 79.6-100% |
| EBV VCA IgG (Retrospective) | High positive percent agreement across serological statuses | |
| Acute (Positive) | N/A (implied high agreement) | 93.4% (99/106), 95% CI: 87-96.8% |
| Acute (Positive, second entry) | N/A (implied high agreement) | 100% (8/8), 95% CI: 67.6-100% |
| No Infection (Positive) | N/A (implied high agreement) | 100% (1/1), 95% CI: 20.7-100% |
| Indeterminate (Positive) | N/A (implied high agreement) | 93.9% (31/33), 95% CI: 80.4-98.3% |
| EBV EBNA-1 IgG (Prospective) | High positive percent agreement across serological statuses | |
| Acute (Negative) | N/A (implied high agreement) | 100% (60/60), 95% CI: 94-100% |
| Late Acute (Positive) | N/A (implied high agreement) | 94.2% (65/69), 95% CI: 86-97.7% |
| Late Acute (Negative) | N/A (implied high agreement) | 100% (3/3), 95% CI: 43.8-100% |
| Recovering (Negative) | N/A (implied high agreement) | 100% (1/1), 95% CI: 20.7-100% |
| Previous Infection (Positive) | N/A (implied high agreement) | 93.7% (266/284), 95% CI: 90.2-96% |
| Previous Infection (Negative) | N/A (implied high agreement) | 92.9% (13/14), 95% CI: 68.5-98.7% |
| No Infection (Negative) | N/A (implied high agreement) | 99.6% (226/227), 95% CI: 97.5-99.9% |
| Indeterminate (Positive) | N/A (implied high agreement) | 76.3% (29/38), 95% CI: 60.8-87% |
| Indeterminate (Negative) | N/A (implied high agreement) | 100% (27/27), 95% CI: 87.5-100% |
| EBV EBNA-1 IgG (Retrospective) | High positive percent agreement across serological statuses | |
| Primary Acute (Negative) | N/A (implied high agreement) | 99.1% (105/106), 95% CI: 94.8-99.8% |
| Late Acute (Negative) | N/A (implied high agreement) | 100% (4/4), 95% CI: 51-100% |
| No Infection (Negative) | N/A (implied high agreement) | 100% (2/2), 95% CI: 34.2-100% |
| Indeterminate (Negative) | N/A (implied high agreement) | 100% (26/26), 95% CI: 87.1-100% |
| EBV EA-D IgG (Prospective) | High positive percent agreement across serological statuses | |
| Primary Acute (Positive) | N/A (implied high agreement) | 93% (40/43), 95% CI: 81.4-97.6% |
| Primary Acute (Negative) | N/A (implied high agreement) | 76.5% (13/17), 95% CI: 52.7-90.4% |
| Late Acute (Positive) | N/A (implied high agreement) | 80.4% (41/51), 95% CI: 67.5-89% |
| Late Acute (Negative) | N/A (implied high agreement) | 81% (17/21), 95% CI: 60-92.3% |
| Recovering (Positive) | N/A (implied high agreement) | 0% (0/1), 95% CI: 0-79.3% (Note: This single sample result is concerning) |
| Previous Infection (Negative) | N/A (implied high agreement) | 96% (286/298), 95% CI: 93.1-97.7% |
| No Infection (Negative) | N/A (implied high agreement) | 98.2% (223/227), 95% CI: 95.6-99.3% |
| Indeterminate (Positive) | N/A (implied high agreement) | 26.9% (7/26), 95% CI: 13.7-46.1% |
| Indeterminate (Equivocal) | N/A (implied high agreement) | 6.3% (2/32), 95% CI: 1.7-20.1% |
| Indeterminate (Negative) | N/A (implied high agreement) | 62.2% (23/37), 95% CI: 46.1-75.9% |
| EBV EA-D IgG (Retrospective) | High positive percent agreement across serological statuses | |
| Primary Acute (Positive) | N/A (implied high agreement) | 93.4% (57/61), 95% CI: 84.3-97.4% |
| Primary Acute (Negative) | N/A (implied high agreement) | 77.8% (35/45), 95% CI: 63.7-87.5% |
| Late Acute (Positive) | N/A (implied high agreement) | 100% (3/3), 95% CI: 43.8-100% |
| Late Acute (Negative) | N/A (implied high agreement) | 80% (4/5), 95% CI: 37.6-96.4% |
| No Infection (Negative) | N/A (implied high agreement) | 100% (2/2), 95% CI: 34.2-100% |
| Indeterminate (Positive) | N/A (implied high agreement) | 66.7% (8/12), 95% CI: 39.1-86.2% |
| Indeterminate (Equivocal) | N/A (implied high agreement) | 0% (0/14), 95% CI: 0-21.5% |
| Indeterminate (Negative) | N/A (implied high agreement) | 40.9% (9/22), 95% CI: 23.3-61.3% |
2. Sample Size Used for the Test Set and Data Provenance
- Total Sample Size (Test Set): 873 samples
- Prospective Samples: 723 samples (sequentially submitted for routine EBV testing, masked).
- Retrospective Samples: 150 samples (pre-selected based on EBV VCA concentrations from a FDA-cleared device, likely to be cases with presumed acute infection).
- Data Provenance: United States
- Samples were collected at three sites:
- A hospital laboratory located in the Northeast (USA)
- A pediatric hospital laboratory located in the Mid-West (USA)
- Focus Diagnostics (manufacturer's site)
- Samples were collected at three sites:
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not mention the use of "experts" in the traditional sense (e.g., radiologists, pathologists) to establish ground truth for the test set.
Instead, the ground truth was established by comparison to commercially available, FDA-cleared predicate devices and an algorithm based on serological profiles.
- For VCA IgG, the ground truth was a "consensus predicate" derived from a combination of:
- FDA-cleared commercially available ELISA
- FDA-cleared commercially available immunofluorescent (IFA) test
- FDA-cleared commercially available flow cytometry-based immunoassay
- For EBNA-1 IgG and EA-D IgG, the ground truth was a single commercially available ELISA test.
- Additionally, the "Serological status was determined by the use of commercially available ELISA assays for the EBV analytes EBNA-1 IgG, VCA IgG and VCA IgM and a commercially available heterophile rapid test for the Heterophile antibody." This indicates a comprehensive panel of existing diagnostic tests was used to define the overall EBV serological status that the Plexus device was compared against.
4. Adjudication Method for the Test Set
- For Plexus EBV VCA IgG vs. Consensus Predicate: A consensus-based algorithm (2/3 majority rule) was used to determine the predicate result for comparison with the Plexus VCA IgG result. This means that out of the three predicate devices, at least two had to agree on the classification (positive/negative) for a sample to have a definitive "consensus predicate" result. If a 2/3 majority could not be obtained, the sample was reported as "No consensus."
- For Plexus EBV EBNA-1 IgG and Plexus EBNA-1 EA-D IgG: The document implies a direct comparison to a single commercially available ELISA, so a specific adjudication method like 2/3 majority would not apply in that instance.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study is an in-vitro diagnostic device (IVD) performance study, comparing the device's output to established predicate tests, not measuring human reader performance with or without AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, this was a standalone performance study. The Plexus EBV IgG Multi-Analyte Diagnostics device is an immunoassay kit that generates qualitative results based on fluorescence measurements and automated calculations using Plexus software (as stated in the "Interpretation of test results" section). Its performance was evaluated on its own, comparing its output to that of predicate immunoassay devices. It does not involve human interpretation as a primary output.
7. The Type of Ground Truth Used
The ground truth used was a composite gold standard based on multiple commercially available, FDA-cleared predicate serological assays and a serological algorithm. Specifically:
- For VCA IgG: Consensus from three predicate immunoassays (ELISA, IFA, flow cytometry-based).
- For EBNA-1 IgG and EA-D IgG: Results from a single predicate ELISA.
- The overall "serological status" (e.g., Primary Acute, Late Acute, Previous Infection, No Infection) was classified using an algorithm based on a panel of results from commercially available ELISA assays (EBNA-1 IgG, VCA IgG, VCA IgM) and a heterophile rapid test. This represents an interpretation based on established diagnostic algorithms using multiple reference methods.
8. The Sample Size for the Training Set
The document does not provide information on a training set sample size. This study appears to be solely focused on validating the performance of the device against predicate methods on a test set. Immunoassays typically do not have a "training set" in the same way machine learning algorithms do, as their "learning" or calibration is part of the assay development and reagent formulation process. If any internal calibration or optimization was performed, it is not detailed in this summary.
9. How the Ground Truth for the Training Set Was Established
Since no training set details are provided, the method for establishing its ground truth is also not available in the document.
§ 866.3235 Epstein-Barr virus serological reagents.
(a)
Identification. Epstein-Barr virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to Epstein-Barr virus in serum. The identification aids in the diagnosis of Epstein-Barr virus infections and provides epidemiological information on diseases caused by these viruses. Epstein-Barr viruses are thought to cause infectious mononucleosis and have been associated with Burkitt's lymphoma (a tumor of the jaw in African children and young adults) and postnasal carcinoma (cancer).(b)
Classification. Class I (general controls).