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The ARCHITECT HSV-1 IgG assay is a chemiluminescent microparticle immunoassay (CMIA) used for the qualitative detection of specific IgG antibodies to herpes simplex virus type 1 (HSV-1) in human serum (collected in serum and serum separator tubes) and plasma (collected in dipotassium EDTA, lithium heparin plasma separator tubes) on the ARCHITECT i System.

The ARCHITECT HSV-1 IgG assay is to be used for testing sexually active adults or expectant mothers to aid in the presumptive diagnosis of HSV-1 infection. The test results may not determine the state of active lessociated disease manifestations, particularly for primary infection. The predictive value of a reactive or nonreactive result depends on the prevalence of HSV-1 infection in the population and the pre-test likelihood of HSV-1 infection.

NOTE: The performance of the ARCHITECT HSV-1 IgG assay has not been established for use in the pediatric population, for neonatal screening, or for testing immunosompromised or immunosuppressed patients. The assay has not been FDA cleared or approved for screening blood or plasma donors.

This assay is an automated, two-step immunoassay for the qualitative detection of specific IgG antibodies to HSV-1 in human serum and plasma using chemiluminescent microparticle immunoassay (CMIA) technology. Sample, HSV-1 specific recombinant gG1 antigen coated paramagnetic microparticles, and assay diluent are combined and incubated. The IgG antibodies to HSV-1 (HSV-1 IgG) present in the sample bind to the HSV-1 specific recombinant gG1 antigen coated microparticles. The mixture is washed. Anti-human IgG acridinium-labeled conjugate is added to create a reaction mixture and incubated. Following a wash cycle, Pre-Trigger and Trigger Solutions are added. The resulting chemiluminescent reaction is measured as a relative light unit (RLU). There is a relationship between the amount of HSV-1 IgG in the sample and the RLU detected by the system optics. The presence or absence of HSV-1 IgG in the sample is determined by comparing the chemiluminescent RLU in the reaction to the cutoff RLU determined from an active calibration.

Here's a breakdown of the acceptance criteria and the studies performed for the ARCHITECT HSV-1 IgG assay, based on the provided document:

Acceptance Criteria and Device Performance

Study Details

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Tube Type Matrix Comparison: 62 sets of unique human serum samples, with each set including samples collected in serum, serum separator, dipotassium EDTA plasma, lithium heparin plasma, and lithium heparin plasma separator tubes.
  • Data Provenance: Not explicitly stated, but the company is based in Barcelona, Spain and the clinical study was conducted in the US. The type of samples suggests they would be clinical specimens. (Retrospective/Prospective not specified for this specific study, but the clinical agreement study was prospective).
• Precision (20-Day): 80 replicates per sample type (Negative Control, Positive Control, 3 Serum Panels, 3 Plasma Panels). Total of 8 samples * 80 replicates = 640 tests per reagent/calibrator lot combination (3 combinations used).
  • Data Provenance: Human serum and plasma panel samples. (Country/Retrospective/Prospective not specified for this specific study).
• Precision (12-Day): 96 replicates per sample type (2 Serum Panels, 2 Plasma Panels). Total of 4 samples * 96 replicates = 384 tests per lot combination (2 reagent lots).
  • Data Provenance: Human serum and plasma panel samples. (Country/Retrospective/Prospective not specified for this specific study).
• Reproducibility: 90 replicates per sample type (Negative Control, Positive Control, 3 Serum Panels, 3 Plasma Panels) across 3 sites.
  • Data Provenance: Human serum and plasma panel samples. (Country/Retrospective/Prospective not specified for this specific study).
• Interference (Endogenous & Drugs): Not a direct sample count, but 12 replicates for each negative and low reactive HSV-1 IgG sample for each substance tested.
  • Data Provenance: HSV-1 IgG negative and low reactive samples. (Country/Retrospective/Prospective not specified for this specific study).
• Cross-Reactivity: Total of 244 specimens (sum of 'n' column in the table).
  • Data Provenance: Specimens from individuals with antibodies to other microorganisms or medical conditions unrelated to HSV-1. Confirmed negative for HSV-1 IgG by a comparator immunoblot method. (Country/Retrospective/Prospective not specified for this specific study).
• CDC Panel Agreement: 100 aliquots (2 aliquots each of 50 serum samples).
  • Data Provenance: Obtained from the Centers for Disease Control and Prevention (CDC). Serum samples with unknown HSV-1 status, implying they are real-world clinical samples. (Country would be USA, retrospective).
• Clinical Agreement Study: 915 specimens.
  • Data Provenance: Collected prospectively within the US. Included sexually active individuals and pregnant females. Tested at 3 independent external laboratories.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

• Clinical Agreement Study: A "composite comparator method" was used, consisting of:
  • A commercially available anti-HSV-1 IgG immunoblot method.
  • A Western Blot reference confirmatory test (University of Washington, Seattle).
• The document does not specify the number of experts or their qualifications for establishing the ground truth using these comparator methods. It refers to the methods themselves as the ground truth.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

• Clinical Agreement Study: The "composite comparator method" suggests an adjudication process, where the immunoblot results were presumably confirmed or clarified by the Western Blot. However, the exact adjudication method (e.g., 2+1, 3+1) is not explicitly detailed. The document only states the combination of methods used to establish the comparator.

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 device is an automated, two-step chemiluminescent microparticle immunoassay (CMIA), not an AI-based imaging or diagnostic tool that involves human readers interpreting results. Therefore, an MRMC comparative effectiveness study comparing human readers with and without AI assistance is not applicable and was not performed.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

• Yes, the performance studies described (Precision, Interference, Cross-Reactivity, CDC Panel Agreement, and Clinical Agreement) all represent standalone performance of the ARCHITECT HSV-1 IgG assay. The device is fully automated and provides a qualitative result (reactive/nonreactive) based on the measured Relative Light Unit (RLU) compared to a cutoff. There is no human interpretation of the assay's output involved in its primary function.

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

• Tube Type Matrix Comparison, Precision, Interference: These studies used internal controls, spiked samples, or reference materials. The "ground truth" for these is defined by the expected values of these controls/samples.
• Cross-Reactivity: Comparator method (immunoblot) confirmed negative for HSV-1 IgG.
• CDC Panel Agreement: The "unknown HSV-1 status" samples from the CDC would have their 'true' status determined by the CDC's reference methods, which serve as the ground truth.
• Clinical Agreement Study: A composite comparator method comprising a commercially available anti-HSV-1 IgG immunoblot method and a Western Blot reference confirmatory test (University of Washington, Seattle). This acts as the "expert consensus" or "reference method" ground truth for the clinical samples.

8. The sample size for the training set

• The document does not specify a training set size because this device is an immunoassay, not a machine learning or AI algorithm that typically requires a separate training set. Immunoassays are developed through analytical optimization and validation, rather than model training.

9. How the ground truth for the training set was established

• As this is an immunoassay and not an AI/ML algorithm, there isn't a "training set" in the conventional sense used for machine learning. The development process would involve optimizing reagents and assay parameters against known positive and negative controls and clinical samples, but these are part of the assay development and validation, not a distinct "training set" for an algorithm.

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