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The PANBIO West Nile Virus IgM Capture ELISA is for the qualitative presumptive detection of IoM antibodies to West Nile virus in serum as an aid in the clinical laboratory diagnosis of West Nile virus infection in patients with clinical symptoms consistent with encephalitis / meningitis. Positive results must be confirmed by plaque reduction neutralization test (PRNT), or by using the current Centers for Disease Control and Prevention (CDC) guidelines for diagnosis of this disease.

Assay performance characteristics have not been established for testing cord blood, neonate, prenatal screening, general population screening without symptoms of meningioencephalitis or automated instruments. The user is responsible for establishing these assay performance characteristics.

Caution: Cross-reactivity has been noted with the PANBIO West Nile IgM assay in specimens containing rheumatoid factor (RF). Reactive results must be reported with a caution statement regarding possible cross-reactivity with RF.

The West Nile Virus IgM Capture ELISA is an Enzyme Linked Immunosorbent Assay (ELISA) for the qualitative detection of IgM antibodies to West Nile virus in serum as an aid in the clinical laboratory diagnosis of West Nile virus in patients with clinical symptoms consistent with encephalitis / meningitis.

Acceptance Criteria and Device Performance Study for PANBIO West Nile Virus IgM Capture ELISA

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria (e.g., "The device must achieve at least X% sensitivity and Y% specificity"). However, the performance characteristics obtained serve as the benchmark for clearance. Given the context of a 510(k) summary, the "reported device performance" essentially functions as the de facto acceptance criteria, demonstrating substantial equivalence to the predicate device.

*CI = Exact confidence interval
¹ Sixteen samples testing indeterminate by IFA and negative by PANBIO were assigned to "IgM positive" for worst-case.
² Seven samples testing indeterminate by IFA and positive by PANBIO were assigned to "IgM negative" for worst-case.

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

• Study Site 1:
  • Total Samples: 420 retrospective sera
  • PRNT-confirmed subset: 130 samples (61 WNV positive, 69 WNV negative)
  • CDC MAC EIA presumptively characterized subset: 73 samples (11 WNV positive, 62 WNV negative)
  • IgM IFA presumptively characterized subset: 419 samples (96 IgM positive, 23 indeterminate, 300 negative) (Note: The sum is 419, not 420. One sample might have been excluded or lost from the initial 420).
  • Data Provenance (Country of Origin and Retrospective/Prospective): Retrospective sera from individuals in various locations:
    • California, USA (blood donation center)
    • Maryland, USA (private reference laboratory)
    • Utah, USA (private reference laboratory)
    • Texas, USA (university medical branch)
    • Minnesota, USA (private laboratory)
    • Canada (government medical laboratory)
• Study Site 2:
  • Total Samples: 51 retrospective sera confirmed by PRNT. These were encephalitis/meningitis patients.
  • Data Provenance (Country of Origin and Retrospective/Prospective): Retrospective sera from patients collected in 2002 at a hospital laboratory in Ohio, USA.
• Specificity of IgM Detection: 10 serum samples for DTT treatment, 8 serum samples for IgG interference. Provenance not specified but likely conducted in-house.
• Reproducibility: Not directly a test set for clinical performance; 27 observations for each of 9 samples.
• Cross-Reactivity: 160 specimens from patients with confirmed diseases other than WNV. Provenance not explicitly stated for individual samples, but the study was conducted at "Study Site 1" and "Study Site 2" (Ohio) and in-house at PANBIO.

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

The document does not explicitly state the number of experts or their specific qualifications (e.g., radiologist with X years of experience) who established the ground truth for the test sets. Instead, the ground truth was established by:

• Plaque Reduction Neutralization Test (PRNT): A laboratory method considered the gold standard for WNV confirmation. This is a laboratory assay, not an expert panel judgment in the traditional sense.
• CDC MAC EIA: Presumptive characterization based on another laboratory assay.
• WNV IgM IFA: Presumptive characterization based on another laboratory assay.

The characterization of specimens was performed by recognized laboratory methods, not by human expert adjudication of individual cases.

4. Adjudication Method for the Test Set

The ground truth for the clinical performance studies was established using laboratory reference assays:

• Plaque Reduction Neutralization Test (PRNT): Used to "confirm" WNV positive/negative status for the primary sensitivity/specificity calculations. This acts as the independent "adjudicator."
• CDC MAC EIA and WNV IgM IFA: Used for presumptive characterization for additional agreement studies.

There was no human expert adjudication method described (e.g., 2+1, 3+1 consensus) for the test sets. The laboratory results themselves served as the reference standard.

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done.

This device is an Enzyme Linked Immunosorbent Assay (ELISA) for the qualitative detection of IgM antibodies, which means it is a laboratory diagnostic test. It is not an AI-powered device or an imaging interpretation system that would involve human readers or AI assistance in the way typically discussed in MRMC studies. The device itself performs the detection.

6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, the performance study was a standalone (algorithm only) evaluation.

The PANBIO West Nile Virus IgM Capture ELISA is an in-vitro diagnostic device that directly produces a result (positive, equivocal, negative) based on the biochemical reaction. Its performance was evaluated by directly comparing its output to established reference laboratory methods (PRNT, CDC MAC EIA, IgM IFA). There is no "human-in-the-loop" component in the sense of a human interpreting the device's output to make a primary diagnosis; the output is the diagnostic aid.

7. The Type of Ground Truth Used

The ground truth used in the performance studies was primarily laboratory reference assays:

• Plaque Reduction Neutralization Test (PRNT): Considered the gold standard for WNV confirmation.
• CDC MAC EIA (ELISA): Another established laboratory assay for WNV IgM detection.
• WNV IgM IFA (Immunofluorescence Assay): Another laboratory assay for WNV IgM detection.

For the cross-reactivity study, the ground truth was based on specimens from patients with confirmed diseases other than WNV.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of device development. This is typical for traditional ELISA-based diagnostic kits, where the assay principles and reagents are developed and optimized rather than "trained" in the machine learning sense. The performance characteristics are then verified using independent test sets as described.

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

Since a "training set" (as understood in machine learning/AI) is not typically applicable to this type of device, the concept of establishing ground truth for it is also not relevant here. The device's components and parameters are likely optimized through laboratory R&D processes based on known positive and negative controls.

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