(92 days)
The Gold Standard Diagnostics Borrelia burgdorferi IgG/IgM ELISA Test Kit is intended as a qualitative presumptive (first-step) test for the detection of IgG and IgM antibodies to B. burgdorferi sensu stricto in human serum from symptomatic patients or people suspected of infection. Positive and equivocal results must be supplemented by testing with a second-step Western blot assay.
The kit includes 12 x 8 well Antigen Coated strips, Conjugate, Substrate, Stop Solution, Wash Buffer. Diluent. Negative Control. Positive Control. The control. The controls are provided to determine if the assay is functioning properly and to determine the antibody level. The reagents are sufficient for 96 determinations.
During the test procedure, antibodies to B. burgdorferi (sensu stricto) if present in the human serum sample will bind to the antigens coated onto the wells forming antigen-antibody complexes. Excess antibodies are removed by washing. A conjugate of goat anti-human IgG/IgM antibodies conjugated with horseradish peroxidase are then added, which binds to the antigen-antibody complexes. Excess conjugate is removed by washing. This is followed by the addition of a chromogenic substrate, tetramethylbenzidine (TMB). If specific antibodies to the antigen are present in the patients' serum, a blue color will develop. The enzymatic reaction is then stopped with a stopping solution causing the contents of the well to turn yellow. The wells are read photometrically with a microplate reader at 450nm.
The antigens used in the Gold Standard Diagnostics Borrelia burgdorferi IgG/IgM ELISA Test kit is a combination of B. burgdorferi sensu strain B31 lysate, B. burgdorferi sensu stricto strain 2591 lysate, and a recombinant VIsE from B. burgdorferi sensu stricto strain B31. The lysates use spirochetes growing in BSK-H complete medium until mid-exponential phase. The recombinant VlsE protein is produced in E. coli SURE2 cells and purified by affinity chromatography. The purity of each antigen is assayed by SDS-PAGE followed by Coomassie staining and/or Western blotting.
Here's an analysis of the acceptance criteria and the study proving the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are not explicitly stated as distinct numerical targets in the provided document. Instead, the document demonstrates substantial equivalence to a predicate device and provides performance metrics from various studies. Based on the studies performed, the "reported device performance" is presented in the context of sensitivity, specificity, agreement with the predicate device, precision, and reproducibility.
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Analytical Specificity (Non-endemic region) | 98.0% (2 cases positive/equivocal out of 100 samples) |
| Analytical Specificity (Endemic region) | 97.3% (3 cases positive/equivocal out of 110 samples) |
| Precision (Within-Run CV) | Moderate Positive: 4.2%; Low Positive: 2.2%; High Negative: 3.4%; Negative: 6.6% |
| Precision (Total CV) | Moderate Positive: 8.9%; Low Positive: 11.9%; High Negative: 11.4%; Negative: 11.6% |
| Reproducibility (Within-Run CV) | Moderate Positive: 5.3%; Low Positive: 4.3%; High Negative: 5.0%; Negative: 9.1% |
| Reproducibility (Total CV) | Moderate Positive: 9.0%; Low Positive: 9.4%; High Negative: 12.8%; Negative: 23.0% |
| Cross-Reactivity (Demonstrated absence of significant interference from listed conditions) | Low false positive rates observed for conditions like Tick-borne Relapsing Fever (7.7%), Treponemal Infections (8.7%), Fibromyalgia (10%); 0% for Rickettsia, Ehrlichiosis, Babesiosis, Leptospirosis, Parvovirus B19, Influenza A&B, Epstein-Barr Virus, Cytomegalovirus, H. pylori, Rheumatoid Arthritis, Herpes Simplex Virus, Varicella Zoster Virus, Autoimmune Disease. (Note: 2 Treponemal Infection samples were also positive on the predicate device). |
| Interfering Substances (Demonstrated no effect) | None detected for Albumin, Bilirubin, Cholesterol, Hemoglobin, Triglycerides at specified concentrations. |
| Positive Percent Agreement with Predicate Device | 96.0% (72/75), 95% CI (88.8% - 99.2%) |
| Negative Percent Agreement with Predicate Device | 97.5% (434/445), 95% CI (95.6% - 98.8%) |
| Clinical Sensitivity (Overall from Sensitivity Study) | Early: 76.3%; Disseminated: 100.0%; Late: 97.2% |
| Clinical Sensitivity (CDC Panel) | Healthy: 100%; Early (0-2m): 86.7%; Convalescent (3-12m): 53.8%; Late (>1yr): 100% |
| Equivalence to Predicate Device | Demonstrated substantial equivalence through comparative performance in clinical and analytical studies. |
2. Sample Sizes and Data Provenance
- Test Set (Clinical Studies):
- Comparison with Predicate Device: 520 serum samples (prospective samples).
- Sensitivity Study (Clinically Characterized): 89 clinically characterized samples.
- CDC Panel: 40 samples (5 healthy, 35 Lyme disease stratified by stage).
- Analytical Specificity: 210 asymptomatic individuals (110 from endemic region/Pennsylvania, 100 from non-endemic region/Arizona).
- Cross-Reactivity: 221 samples (obtained from serum vendors, confirmed positive for respective markers).
- Interfering Substances: 3 samples (negative, low positive, moderate positive, spiked).
- Data Provenance: The data appears to be from a mix of regions within the US (Pennsylvania, Arizona for specificity, CDC for panel), and some samples from "serum vendors" for cross-reactivity. The clinical comparison study used "prospective samples submitted for Lyme serology testing" from three sites (one internal, two external reference laboratories). The sensitivity study used "clinically characterized samples."
3. Number of Experts and Qualifications for Ground Truth (Test Set)
- The document does not specify the number or qualifications of experts used to establish ground truth for the test set in the comparative clinical studies or sensitivity studies.
- For the "clinically characterized samples" and "patients diagnosed with Lyme disease" (CDC panel), it is implied that a clinical diagnosis (made by medical professionals) served as the ground truth, but no details on the specific experts (e.g., infectious disease specialists, their experience) are provided.
- For cross-reactivity, samples were from "serum vendors who confirmed their positivity for each respective marker," which likely relied on established diagnostic methods but doesn't detail expert involvement.
4. Adjudication Method (Test Set)
- The document does not describe a specific adjudication method (e.g., 2+1, 3+1, none) for resolving discrepancies in the test set.
- For the "Comparison with Predicate Device" table, "Equivocal samples counted as positive" is an interpretation rule, not an adjudication method for ground truth.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is an in-vitro diagnostic (IVD) ELISA test kit, which is a laboratory assay and does not involve human readers interpreting results in the same way an imaging AI would. Therefore, the concept of human readers improving with AI assistance is not applicable here.
6. Standalone Performance (Algorithm Only)
- Yes, the performance presented for the "Gold Standard Diagnostics Borrelia burgdorferi IgG/IgM ELISA Test Kit" throughout the document (e.g., Precision, Reproducibility, Analytical Specificity, Cross-Reactivity, and its results in the Clinical Sensitivity and CDC Panel studies) is its standalone performance. This test kit is a self-contained diagnostic assay.
7. Type of Ground Truth Used
- Clinical Diagnosis/Characterization: For the sensitivity study and the CDC panel, the ground truth was based on "clinically characterized samples" and "patients diagnosed with Lyme disease," implying a clinical diagnosis by medical professionals.
- Absence of Disease/Asymptomatic Status: For the analytical specificity study, ground truth was derived from "asymptomatic individuals" from endemic and non-endemic regions, presumed to be negative for Lyme disease.
- Confirmed Positivity: For the cross-reactivity study, samples were from "serum vendors who confirmed their positivity for each respective marker."
- ELISA Results (Predicate Device): For the "Comparison with Predicate Device" study, the predicate device's results served as a comparative reference point, but not necessarily the ultimate gold standard for true disease status.
8. Sample Size for the Training Set
- The document implicitly references a "training set" for the establishment of the assay cutoff: "The cutoff was determined by testing a total of 200 normal sera which consisted of 100 sera from an endemic region of Lyme disease and 100 sera from a non-endemic region of Lyme disease."
- Additionally, after initial cutoff determination, "125 characterized Lyme disease samples were tested" and an ROC analysis was generated with the 325 samples (200 normal and 125 characterized samples) "to verify the chosen cutoff." This combined set of 325 samples served as a "training" or calibration set for optimizing the assay's cutoff.
9. How the Ground Truth for the Training Set was Established
- For the "training set" used to determine the assay cutoff:
- Normal Sera: The 200 normal sera were obtained from "an endemic region of Lyme disease and a non-endemic region of Lyme disease." Their "normal" status implies they were considered negative for Lyme disease based on clinical assessment or lack of symptoms/exposure.
- Characterized Lyme Disease Samples: The 125 "characterized Lyme disease samples" likely had a confirmed clinical diagnosis of Lyme disease, although specific details of this characterization are not provided. The phrase "characterized Lyme disease samples" implies a definitive diagnosis beyond just a positive test.
§ 866.3830
Treponema pallidum treponemal test reagents.(a)
Identification. Treponema pallidum treponemal test reagents are devices that consist of the antigens, antisera and all control reagents (standardized reagents with which test results are compared) which are derived from treponemal sources and that are used in the fluorescent treponemal antibody absorption test (FTA-ABS), theTreponema pallidum immobilization test (T.P.I.), and other treponemal tests used to identify antibodies toTreponema pallidum directly from infecting treponemal organisms in serum. The identification aids in the diagnosis of syphilis caused by bacteria belonging to the genusTreponema and provides epidemiological information on syphilis.(b)
Classification. Class II (performance standards).