(273 days)
Light Diagnostics SimulFluor™ HSV/VZV Immunofluorescence Assay is a direct immunofluorescence test intended for the simultaneous detection and identification of HSV 1 and 2 and varicella-zoster virus (VZV) from patients with vesicular, oral, genital, or skin lesions, and following amplification of virus in culture. Specimens found to be negative on direct specimen examination should be tested by cell culture.
Light Diagnostics SimulFluor™ HSV/VZV Immunofluorescence Assay utilizes a single reagent for the simultaneous detection and identification of HSV and VZV. The primary component, specific for both HSV 1 and 2 will bind to 155kD major capsid protein in HSV-infected cells. The secondary component, specific for VZV, will bind to glycoprotein gp I and the immediate early antigen in VZV-infected cells. Unbound reagent is removed by rinsing with phosphate-buffered saline (PBS). Illumination with ultraviolet light allows visualization of the antigen-antibody complexes by fluorescence microscopy. When a FITC filter set is used, the HSV antigen-antibody complex will exhibit an apple green fluorescence and the VZV antigen-antibody complex will fluoresce yellow-gold. Uninfected cells stain a dull red due to the presence of Evans blue in the reagent.
A blend of monoclonal antibodies directed against HSV and VZV is used in the Light Diagnostics SimulFluor™ HSV/VZV reagent. The use of monoclonal antibodies ensures increased specificity of the reagent and reduces the risk of non-specific background or interference.
Here's a summary of the acceptance criteria and study details for the Light Diagnostics SimulFluor™ HSV/VZV Immunofluorescence Assay, based on the provided text:
Acceptance Criteria and Reported Device Performance
The document does not explicitly state pre-defined acceptance criteria (e.g., "the device must achieve a sensitivity of at least X%"). Instead, it reports the performance of the device and concludes that it is "substantially equivalent" to predicate devices, thus demonstrating safety and effectiveness. The reported performance metrics are presented below.
| Metric | Site 1 (Direct Specimen) - HSV | Site 1 (Direct Specimen) - VZV | Site 2 (Direct Specimen) - HSV | Site 2 (Direct Specimen) - VZV |
|---|---|---|---|---|
| Sensitivity | 64.7% (CI 50.1-77.62%) | 100% (CI 83.2-100%) | 82.4% (CI 56.6-96.2%) | 100% (CI 71.5-100%) |
| Specificity | 97.5% (CI 91.3-99.7%) | 85.7% (CI 79.2-92.2%) | 99.5% (CI 97.5-100%) | 99.1% (CI 96.9-99.9%) |
| Metric | Site 1 (Culture Amplification) - HSV | Site 1 (Culture Amplification) - VZV |
|---|---|---|
| Relative Sensitivity | 100% (CI 93.8-100%) | 95.2% (CI 76.2-99.9%) |
| Relative Specificity | 100% (CI 97.1-100%) | 100% (CI 97-100%) |
Study Details
-
Sample sizes used for the test set and the data provenance:
- Site 1 (Northeast US): 203 specimens tested for HSV or VZV.
- Site 2 (West Coast US): 283 specimens submitted for HSV and/or VZV testing; 236 specimens tested for HSV and VZV in direct specimens.
- Data Provenance: Clinical evaluations were conducted at two separate hospital laboratories in the US (Northeast and West Coast). The data is retrospective, as it involves the comparison of direct patient specimens and cell cultures.
-
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The document does not specify the number of experts or their qualifications for establishing ground truth. The ground truth was established by "culture confirmation."
-
Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- The document does not describe any specific adjudication method for discrepancy resolution. Ground truth was determined solely by "culture confirmation."
-
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:
- No, this was not a multi-reader multi-case (MRMC) comparative effectiveness study involving human readers and AI. This is a study evaluating an immunofluorescence assay (a laboratory test) against predicate devices and culture.
-
If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- This device is a direct immunofluorescence assay, which inherently requires human observation (fluorescence microscopy). Therefore, a "standalone algorithm only" performance is not applicable in the context of this device. The performance reported is the performance of the assay as read by a human.
-
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The primary ground truth used for the clinical evaluation was culture confirmation.
-
The sample size for the training set:
- The document does not describe a "training set" in the context of machine learning. The non-clinical evaluations involved characterization of monoclonal antibodies using "reference viral strains and clinical isolates," but a specific sample size for this characterization is not provided, nor is it analogous to a machine learning training set.
-
How the ground truth for the training set was established:
- Not applicable, as there is no mention of a traditional machine learning training set. The characterization of antibodies involved testing against "reference viral strains and clinical isolates," implying known or well-characterized viral types.
§ 866.3900 Varicella-zoster virus serological reagents.
(a)
Identification. Varicella-zoster virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to varicella-zoster in serum. The identification aids in the diagnosis of diseases caused by varicella-zoster viruses and provides epidemiological information on these diseases. Varicella (chicken pox) is a mild, highly infectious disease, chiefly of children. Zoster (shingles) is the recurrent form of the disease, occurring in adults who were previously infected with varicella-zoster viruses. Zoster is the response (characterized by a rash) of the partially immune host to a reactivation of varicella viruses present in latent form in the patient's body.(b)
Classification. Class II (performance standards).