(295 days)
The Gold Standard Diagnostics Herpes Simplex Virus Type 1 IgG ELISA Test Kit is intended for the qualitative detection of IgG antibodies to Herpes Simplex Virus Type 1 (HSV-1) in human serum. The test is indicated for sexually active individuals and expectant mothers as an aid for the presumptive diagnosis of HSV-1 infection.
The predictive value of positive or negative results depends on the population's prevalence and the pretest likelihood of HSV-1. The test is not intended for screening of blood and plasma donors. The performance of this assay has not been established for use in a pediatric population, neonates, or immunocompromised patients.
The Gold Standard Diagnostics Herpes Simplex Virus (HSV) Type I IgG ELISA Test is an enzyme linked immunosorbent assay for the qualitative detection of IgG antibodies to HSV-1 in human serum. The assay requires a total of 90 minutes incubation time. The test uses microtiter wells coated with a recombinant gG1 protein of HSV-1. Serum is added to each well and incubated for 30 minutes at 37℃. If antibodies are present they will bind to the antigen in the well. Unbound antibodies are removed by washing the wells three times. A Horse Radish Peroxidase (HRP) conjugated goat anti-human IgG (conjugate) is then added to each well and incubated for 30 minutes at 37°C. If antibodies are present in the patient's serum, the conjugate will bind to the antibody attached to the antigen on the wells are again washed to remove any unbound conjugate. In order to detect the bound conjugate a substrate containing tetramethylbenzidine (TMB) is added to each well and incubated for 30 minutes at 37°C. If conjugate is present, the HRP will react with the substrate to generate a colored product. After the incubation period, the reaction is stopped with a . Stop Solution and the color intensity is measured spectrophotometrically. The kit also includes a Wash Buffer, Diluent, a Negative Control, and a Cutoff Control. The cut-off control is used to determine the validity of the assay and subsequently to determine the result of the sample. Positive and Negative controls are provided to determine if the assay is functioning properly. The kit contains 12 x 8well antigen coated microtiter strips in a frame. The reagents are sufficient for 96 determinations.
Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for this device are implicitly defined by its comparison to a legally marketed predicate device (Focus Diagnostics HerpeSelect® 1 and 2 Immunoblot IgG) and by demonstrating acceptable precision, reproducibility, cross-reactivity, and interference performance. The document doesn't explicitly state numerical acceptance criteria for sensitivity and specificity a priori but lists the achieved performance values.
| Test Category | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Clinical Performance | Substantial equivalence to predicate device in intended use populations (pregnant women, sexually active adults, low prevalence). Comparable sensitivity and specificity to predicate. | Pregnant Women: |
| Sensitivity = 96.0% (95% C.I. = 90.1% - 98.9%) | ||
| Specificity = 96.5% (95% C.I. = 90.0% - 99.3%) |
Sexually Active Adults:
Sensitivity = 92.3% (95% C.I. = 88.6% - 95.0%)
Specificity = 95.5% (95% C.I. = 91.8% - 97.8%)
Low Prevalence:
Sensitivity = 93.8% (95% C.I. = 69.7% - 99.8%)
Specificity = 92.9% (95% C.I. = 85.1% - 97.3%)
CDC Seroconversion Panel:
Sensitivity = 97.8% (95% C.I. = 88.5% - 99.9%)
Specificity = 94.4% (95% C.I. = 84.6% - 98.8%) |
| Precision (Within-lab) | Demonstrable precision across various sample types (high positive, moderate positive, low positive, near cutoff, high negative, negative). CV values indicating low variability. | High Positive: SD 1.544, CV 2.6% (within-run); Total CV 13.1%
Moderate Positive: SD 1.290, CV 5.2% (within-run); Total CV 14.6%
Low Positive: SD 0.664, CV 3.7% (within-run); Total CV 15.0%
Near Cutoff: SD 0.601, CV 4.4% (within-run); Total CV 13.7%
High Negative: SD 0.388, CV 5.9% (within-run); Total CV 14.5%
Negative: SD 0.153, CV 8.0% (within-run); Total CV 18.0% |
| Reproducibility | Reproducibility across multiple sites, days, runs, and technicians for various sample types. CV values indicating acceptable variability. | Overall (across 3 sites):
High Positive: Overall Total CV 9.5%
Low Positive: Overall Total CV 14.6%
Positive Cutoff: Overall Total CV 5.2%
Negative Cutoff: Overall Total CV 2.9%
High Negative: Overall Total CV 10.9%
Negative: Overall Total CV 14.6%
(Site-specific data also provided with similar CVs) |
| Cross-Reactivity | Minimal or no cross-reactivity with common infectious diseases and conditions. If reactive, it should align with predicate device. | 10 tested for each with: CMV (0 reactive), EBV (1* reactive), VZV (1* reactive), Chlamydia trachomatis (0 reactive), Treponema pallidum (0 reactive), HPV (0 reactive), Rubella Virus (0 reactive), Toxoplasma gondii (3* reactive), Candida albicans (2* reactive), Neisseria gonorrhea (0 reactive), Rheumatoid Factor (0 reactive), ANA (0 reactive), Measles (0 reactive), HSV-2 (0 reactive), HIV (4* reactive), Bacteroides (0 reactive). *Samples also reactive with predicate device. |
| Interfering Substances | Performance unaffected (within ±20%) by specified high concentrations of common interfering substances (hemoglobin, bilirubin, cholesterol, triglycerides, albumin). | Performance not affected by: Hemoglobin (2 g/L), Bilirubin (342 µmol/L), Cholesterol (13 mmol/L), Triglycerides (37 mmol/L), Albumin (60 g/L). (Acceptance criterion of ±20% was used.) |
2. Sample Size Used for the Test Set and Data Provenance
- Clinical Performance Test Set:
- Total Samples: 703 samples.
- Pregnant Women: 185 samples.
- Sexually Active Adults: 518 samples.
- Low Prevalence Population: 96 samples (sera ages 16-19 years old).
- CDC Seroconversion Panel: 100 samples (46 positive, 54 negative - implied from counts).
- Data Provenance:
- Pregnant Women and Sexually Active Adults: Prospectively collected.
- Low Prevalence Population: Prospectively collected in a non-STD setting. Tested in-house.
- CDC Seroconversion Panel: Obtained from the CDC. Tested in-house.
- Cross-reactivity samples: Obtained from serum brokers.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The ground truth for the clinical performance study (the primary test set) was established by comparison to a commercially available predicate device: Focus Diagnostics HerpeSelect® 1 and 2 Immunoblot IgG test (K000238). The document does not mention the use of human experts to establish ground truth for this comparison study, as the predicate device itself serves as the reference.
For the cross-reactivity study, ground truth for the "positive for" status of the samples was confirmed by "serum brokers who confirmed positivity for each respective disease and conditions using FDA cleared tests." The number and specific qualifications of these "serum brokers" or the experts validating the FDA cleared tests are not specified.
4. Adjudication Method for the Test Set
For the clinical performance studies comparing the Gold Standard Diagnostics ELISA to the Focus Diagnostics Line Blot, the adjudication method for discordant results (equivocal results) was explicitly stated: "Equivocal results were treated as the worst case results (disagreement)". This implies that equivocal results were counted as disagreements with the predicate device's result when calculating sensitivity and specificity.
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, an MRMC comparative effectiveness study was not done. This device is an in-vitro diagnostic (IVD) ELISA test, which does not involve human readers interpreting images or data to the extent that an MRMC study for AI would typically describe. The "reading" is done by a spectrophotometer, and the comparison is between two IVD assay technologies.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, the device's performance as an algorithm-only system (an ELISA test measured by a spectrophotometer) was evaluated. The results presented for sensitivity, specificity, precision, reproducibility, cross-reactivity, and interfering substances all represent the standalone performance of the Gold Standard Diagnostics Herpes Simplex Virus Type 1 IgG ELISA Test Kit. There is no human-in-the-loop component described for the operation or interpretation of this particular assay's results.
7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)
The primary type of ground truth used was comparison to a legally marketed predicate device (Focus Diagnostics HerpeSelect® 1 and 2 Immunoblot IgG test).
Additionally:
- For the cross-reactivity panel, the ground truth for specific infections was established by "FDA cleared tests" as reported by serum brokers.
- For the CDC seroconversion panel, the ground truth was based on "well-characterized HSV I serum samples" obtained from the CDC, indicating a highly validated and accepted reference standard.
8. The Sample Size for the Training Set
The document does not mention a training set in the context of an algorithm or machine learning. This is an ELISA kit, which is a biochemical assay, not an AI/ML algorithm that requires training data in the traditional sense. The development and optimization of the ELISA kit would involve internal validation and batch testing, but this is distinct from an AI training set.
9. How the Ground Truth for the Training Set was Established
As explained above, there is no "training set" for this type of device in the AI/ML context. The assay's performance characteristics are established through analytical and clinical studies comparing it to known standards (predicate device, CDC panel) and characterized samples.
§ 866.3305 Herpes simplex virus serological assays.
(a)
Identification. Herpes simplex virus serological assays are devices that consist of antigens and antisera used in various serological tests to identify antibodies to herpes simplex virus in serum. Additionally, some of the assays consist of herpes simplex virus antisera conjugated with a fluorescent dye (immunofluorescent assays) used to identify herpes simplex virus directly from clinical specimens or tissue culture isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by herpes simplex viruses and provides epidemiological information on these diseases. Herpes simplex viral infections range from common and mild lesions of the skin and mucous membranes to a severe form of encephalitis (inflammation of the brain). Neonatal herpes virus infections range from a mild infection to a severe generalized disease with a fatal outcome.(b)
Classification. Class II (special controls). The device is classified as class II (special controls). The special control for the device is FDA's revised guidance document entitled “Class II Special Controls Guidance Document: Herpes Simplex Virus Types 1 and 2 Serological Assays.” For availability of the guidance revised document, see § 866.1(e).