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The Diagnostic Hybrids, Inc D3 DFA Varicella-zoster Virus Identification Kit is intended for use in the qualitative detection of varicella-zoster virus (VZV) in cell cultures by immunofluorescence using fluoresceinated monoclonal antibodies (MAbs). Negative results do not preclude an infection and should not be used as the sole basis for diagnosis, treatment or other management decision. Performance testing has not been done on direct patient specimen testing.

The Diagnostic Hybrids, Inc. D3 DFA VARICELLA-ZOSTER IDENTIFICATION KIT includes a DFA Reagent that contains a blend of two fluorescein-labeled murine monoclonal antibodies directed against VZV antigens. The kit includes the following components: VZV DFA Reagent, Mounting Fluid, VZV Antigen Control Slides, PBS Concentrate.

Here's a breakdown of the acceptance criteria and study information for the Diagnostic Hybrids, Inc. D3 DFA Varicella-zoster Virus Identification Kit, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The 510(k) summary primarily focuses on establishing substantial equivalence to a predicate device rather than defining strict, pre-specified acceptance criteria with numerical targets. Instead, the performance is reported as agreement with the predicate device.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size: 251 specimens (after excluding 3 specimens due to toxic cell culture monolayers from an initial 254 prospectively collected specimens).
• Data Provenance: Prospectively collected specimens. The country of origin is not explicitly stated, but it was collected at "three laboratory sites" which typically implies within the country of submission (USA for FDA approval).

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The ground truth for the test set was established by comparison to a currently marketed Varicella-zoster virus identification kit (the predicate device) which serves as the reference method. No independent experts are mentioned as having adjudicated or established ground truth in this particular type of study (method comparison). The "experts" in this context would be the technicians and microbiologists performing and interpreting the predicate device's results. Their specific qualifications are not detailed in the summary, but it's implied they are qualified laboratory personnel accustomed to these types of assays.

4. Adjudication Method for the Test Set

The adjudication method was a direct comparison between the D3 DFA VZV Identification Kit and a predicate device, serving as the "comparison device." There is no mention of an independent expert adjudication process for discordant results. The table presented shows agreement and disagreement between the two kits.

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This study is a method comparison study between two diagnostic kits, not an evaluation of human reader performance with or without AI assistance.

6. Standalone (Algorithm Only Without Human-in-the-Loop) Performance Study

Yes, a standalone performance study was done. The study evaluates the performance of the D3 DFA Varicella-zoster Virus Identification Kit itself (using immunofluorescence read by a human under a microscope) against a predicate device. This is the "algorithm only" in the context of a laboratory assay, where the "algorithm" is the entire test procedure and the interpretation criteria provided. There is no automated image analysis or AI component involved in the reading of this specific device; it relies on human observation through a fluorescence microscope.

7. Type of Ground Truth Used

The ground truth used was established by comparison to a legally marketed predicate device (Light Diagnostics Varicella-zoster (VZV) Direct Immunofluorescence Assay or Light Diagnostics Simulfluor HSV/VZV Immunofluorescence Assay) which also uses immunofluorescence for VZV detection in cell cultures. This is a form of "reference method" ground truth.

8. Sample Size for the Training Set

The 510(k) summary does not explicitly describe a separate "training set" as would be common for machine learning applications. This is a traditional diagnostic kit submission. The "training" for such a kit involves the development and optimization of the antibodies and reagents by the manufacturer. The data presented in the performance characteristics section (Analytical performance, Analytical Specificity, Comparison Studies) are primarily for validation and demonstrate the kit's performance, not for training a model.

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

As noted above, a distinct "training set" and associated ground truth establishment in the context of statistical model training is not applicable to this type of device (an immunofluorescence assay kit). The development of the kit itself involves internal R&D and quality control, ensuring the antibodies correctly bind to VZV antigens. This developmental process would involve testing against known positive and negative VZV samples, where "ground truth" would be established by standard microbiological techniques (e.g., cell cultures, PCR, viral isolation) for VZV positivity. However, this is part of product development, not a separate "training set" study as described for AI/ML devices.

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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.

Study Details

1. 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.

2. 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."

3. 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."

4. 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.

5. 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.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • The primary ground truth used for the clinical evaluation was culture confirmation.

7. 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.

8. 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.

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