(60 days)
This enzyme-linked immunosorbent assay (ELISA) is indicated for the detection and measurement of circulating IgG antibodies to ß2 Glycoprotein in human serum. The presence of these antibodies, in combination with clinical observations and other serological tests, can aid in the diagnosis of Primary and Secondary Antiphospholipid Syndrome.
An enzyme-linked immunosorbent assay (ELISA) designed for the detection and measurement of IgG antibodies to ß, Glycoprotein I in human serum. The ELISA methodology is commonly used for serum antibody evaluations. Purified human B, glycoprotein has been attached to the inner surfaces of the microwell plate. During the initial incubation step, specific antibodies in patient serum will bind to the antigen and are immobilized on the surface. After incubation and a wash step, a peroxidase labeled anti human IgG (gamma chain specific) second antibody is added to the wells to react with the immobilized anti beta 2 GP1 antibodies. After incubation and another wash step, the substrate is added. In the wells where the specific antigenantibody-HRP complex remains bound, the peroxidase enzyme catalyzes a color change in the substrate. After the enzymatic reaction is stopped, the colored product is read in an EIA plate reader at a specified wavelength.
Here is an analysis of the provided FDA 510(k) summary for the VIRGO® ß₂ Glycoprotein I IgG Antibody Kit, detailing acceptance criteria and study information:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for this device are not explicitly stated as numerical thresholds (e.g., "sensitivity must be > X%", "specificity must be > Y%"). Instead, the document focuses on demonstrating the device's ability to effectively detect IgG antibodies to ß₂ Glycoprotein I in human serum, showing differentiation between positive and negative samples, and agreement with an existing commercial assay.
The reported device performance is presented in tables within the document. Since specific acceptance criteria (numerical targets) are not provided, the table below presents the demonstrated performance metrics as reported. The primary performance metrics are related to diagnostic accuracy (sensitivity, specificity) and precision.
| Performance Metric | Acceptance Criteria (Implicit/Demonstrated) | Reported Device Performance |
|---|---|---|
| Diagnostic Accuracy | Implicit: The device should show clinical utility in detecting IgG antibodies to ß₂ Glycoprotein I in patients with APS and differentiating them from healthy individuals and those with other autoimmune/infectious diseases. It should also show reasonable agreement, sensitivity, and specificity when compared to a commercially available anti-cardiolipin IgG EIA assay. | |
| Initial Clinical Panel | Distinction between patient groups (APS, SLE+APS) and control groups (Rheumatoid Arthritis, SLE (No APS), Scl-70 (No APS), Infectious, Normals). | APS: 74.4% positive (43 samples) SLE + APS: 85.7% positive (7 samples) Rheumatoid Arthritis: 2.5% positive (40 samples) SLE (No APS): 10.0% positive (20 samples) Scl-70 (No APS): 0% positive (20 samples) Infectious: 5.0% positive (40 samples) Normals: 0.8% positive (120 samples) |
| Relative Sensitivity | Implicit: Reasonable sensitivity when compared to a predicate/comparator anti-cardiolipin IgG EIA assay. | 72.7% (95% CI: 60.3% to 82.3%) |
| Relative Specificity | Implicit: Reasonable specificity when compared to a predicate/comparator anti-cardiolipin IgG EIA assay. | 92.6% (95% CI: 83.1% to 97.0%) |
| Relative Agreement | Implicit: Reasonable overall agreement with a predicate/comparator anti-cardiolipin IgG EIA assay. | 81.7% (95% CI: 70.2% to 89.5%) |
| Precision | Implicit: Consistent and reproducible results for inter-assay and intra-assay measurements across various sample types (low, medium, high concentrations, controls, calibrators). Lower % C.V. (Coefficient of Variation) indicates better precision. | |
| Inter Assay % C.V. | No explicit numerical criterion. | Range from 1.7% to 14.6% for samples and controls, 1.7% to 7.5% for calibrator dilutions. |
| Intra Assay % C.V. | No explicit numerical criterion. | Range from 6.1% to 11.6% for samples. |
2. Sample Sizes Used for the Test Set and Data Provenance
-
Initial Clinical Panel:
- Primary APS: 43 samples
- SLE + APS: 7 samples
- Rheumatoid Arthritis: 40 samples
- SLE (No APS): 20 samples
- Scl-70 (No APS): 20 samples
- Infectious: 40 samples
- Normals: 120 samples
- Total for initial clinical panel: 290 samples.
- Data Provenance: The document states "clinically characterized serum specimens" and "characterized serum specimens from individuals diagnosed with Primary APS and other diseases." It does not specify the country of origin. The study appears to be retrospective, as samples were "characterized" (diagnosed) prior to being tested with the device.
-
Comparison with aCL IgG:
- Clinically characterized serum samples: 37 samples (subset of the above panel or overlapping)
- Apparently healthy donors: 23 samples
- Total for comparison with aCL IgG: 60 samples.
- Data Provenance: Same as above, likely retrospective based on prior characterization. No country of origin specified.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document states that the samples were "clinically characterized serum specimens" or "from individuals diagnosed with Primary APS and other diseases." This implies that diagnoses were made by clinicians using standard diagnostic criteria. However, no specific number of experts, their names, or detailed qualifications (e.g., "radiologist with 10 years of experience") are provided for establishing the ground truth for the test set.
4. Adjudication Method for the Test Set
The document does not describe an explicit adjudication method (e.g., 2+1, 3+1) for the diagnoses of the "clinically characterized serum specimens." The implication is that these were established clinical diagnoses.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance
No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This device is an in-vitro diagnostic (IVD) assay designed to directly detect antibodies, not to assist human readers in interpreting images or other data. The comparative study was between the new assay and a predicate/commercial antibody assay (anti-cardiolipin IgG EIA assay), not human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, this was a standalone performance study of the device (assay kit) itself. The device (VIRGO® ß₂ Glycoprotein I IgG Antibody Kit) is an ELISA-based diagnostic test that provides a quantitative or qualitative (positive/negative based on cutoff) result for ß₂ Glycoprotein I IgG antibodies. Its performance characteristics (precision, diagnostic accuracy) were evaluated directly, without human interpretation as part of the primary output, other than reading the EIA plate reader results to determine the optical density.
7. The Type of Ground Truth Used
The ground truth used for the diagnostic accuracy studies was clinical diagnosis. Samples were obtained from individuals who had already been "diagnosed with Primary APS and other diseases." For the "Normals" group, the ground truth was "apparently healthy donors."
8. The Sample Size for the Training Set
The document does not explicitly describe a separate training set or its sample size. The performance data presented appears to be from a single evaluation study using "clinically characterized serum specimens." For IVD kits like this, the "development" or "training" often involves internal optimization of reagents, cutoff determination, and calibration, which typically uses various characterized panels internally, but these are not usually detailed in the same way as a machine learning training set for software. The "Calibrator" samples mentioned in the precision section are for daily assay standardization, not a machine learning training set.
9. How the Ground Truth for the Training Set Was Established
As no explicit training set is described in the provided summary, there is no information on how its ground truth was established. For the overall development of such diagnostics, ground truth would typically be based on established clinical diagnoses and/or reference laboratory results.
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1. Submitter's Name/Contact Person
loseph M. Califano Director, Regulatory Affairs
Address
Hemagen Diagnostics, Inc. 34-40 Bear Hill Road Waltham, MA, 02154
(781) 890-3766 x 257 Phone: (781) 890-3748 Fax: email: jcalifano@hemagen.com
Date Prepared
14 June 1999
Date Revised
25 August 1999
2. Device Name
| Trade Name: | VIRGO® β₂ Glycoprotein I IgG Antibody Kit |
|---|---|
| Common Name: | β₂ Glycoprotein I Antibodies Test System |
| Classification Name: | Multiple Autoantibodies Immunological Test System |
3. Predicate
Hemagen ® Cardiolipin Antibody Kit Trade Name: 510 (k) Docket No. K 932373, SE Date; 16 July 1993
The performance of the VIRGO® ® ß, Glycoprotein I IgC Antibody Kit was evaluated
with a panel of characterized serum specimens from individuals diagnosed with Primary APS and other diseases.
510(k) Summary Page 1
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Description of Device 3.
An enzyme-linked immunosorbent assay (ELISA) designed for the detection and measurement of IgG antibodies to ß, Glycoprotein I in human serum.
The ELISA methodology is commonly used for serum antibody evaluations. Purified human B, glycoprotein has been attached to the inner surfaces of the microwell plate. During the initial incubation step, specific antibodies in patient serum will bind to the antigen and are immobilized on the surface. After incubation and a wash step, a peroxidase labeled anti human IgG (gamma chain specific) second antibody is added to the wells to react with the immobilized anti beta 2 GP1 antibodies. After incubation and another wash step, the substrate is added. In the wells where the specific antigenantibody-HRP complex remains bound, the peroxidase enzyme catalyzes a color change in the substrate. After the enzymatic reaction is stopped, the colored product is read in an EIA plate reader at a specified wavelength.
4. Intended Use of Device
This enzyme-linked immunosorbent assay (ELISA) is intended for the detection and measurement of IgG antibodies to ß, Glycoprotein I in human serum.
5. Technological Characteristics
Proposed Device
The VIRGO ® ß, Glycoprotein I IgG Antibody Kit is an enzyme-linked immunosorbent assay. The device utilizes optical density as a measure of antibody presence, with an established cutoff between a positive and a negative reaction. The device also contains a IgG Calibrator to enable the assignment of arbitrary IgG antibody values to patient samples.
Predicate Device
The Hemagen ® Cardiolipin IgG/IgM Antibody Kit is an enzyme-linked immunosorbent assay. The device utilizes optical density as a measure of antibody presence, with an established cutoff between a positive and a negative reaction. The device also contains both an IgM Calibrator, and an IgG Calibrator to enable the assignment of MPL or GPL unit values to patient samples. The calibrators have been standardized to the IgG standards obtained from Louisville APL Diagnostics, Inc.
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5. Performance Data
Precision
To estimate the overall precision of the VIRGO ® βչ Glycoprotein I lgG Antibody Kit,
inter, and intra assay studies were conducted. The results of these studies is summarize in the tables below
Inter Assay
Three serum samples, the Negative, and Positive Controls, and the Calibrator were assayed five times each, twice a day, on five different days :
| Mean RGU | Std. Deviation | % C.V. | |
|---|---|---|---|
| Sample 1 | 95.7 | 11.2 | 11.7 |
| Sample 2 | 47.5 | 6.9 | 14.6 |
| Sample 3 | 12.1 | 1.7 | 13.9 |
| Neg. Control | < 10 | N/A | N/A |
| Pos. Control | 51.6 | 5.9 | 11.5 |
| Cal Dil 1 | 152.9 | 2.6 | 1.7 |
| Cal Dil 2 | 80.8 | 6.1 | 7.5 |
| Cal Dil 3 | 40.2 | 2.1 | 5.2 |
| Cal Dil 4 | 19.9 | 0.8 | 3.8 |
| Cal Dil 5 | 10.8 | 0.5 | 4.8 |
Intra Assay
The same three serum samples were assayed ten consecutive times in duplicate:
| Mean RMU | Std. Deviation | % C.V.' | |
|---|---|---|---|
| Sample 1 | 91.5 | 5.6 | 6.1 |
| Sample 2 | 49.3 | 5.7 | 11.6 |
| Sample 3 | 16.2 | 1.6 | 9.9 |
000003
ini
510(k) Summary Page 3
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Performance Testing
To demonstrate the effectiveness of the device, a number of clinically characterized serum samples were tested. The results are summarized in the table below:
| Patient Group | Number | Number Positive (%) |
|---|---|---|
| APS1 | 43 | 32 (74.4) |
| SLE + APS | 7 | 6 (85.7) |
| TOTAL | 50 | 38 (76.0) |
| Rheumatoid Arthritis | 40 | 1 (2.5) |
| SLE (No APS) | 20 | 2 (10.0) |
| Scl-70 (No APS) | 20 | 0 (0) |
| Infectious2 | 40 | 2 (5.0) |
| Normals | 120 | 1 (0.8) |
Notes
APS = Antiphospholipid syndrome 1.
The infectious group consisted of samples with positive syphilis serology. 2.
Comparison with aCL IgG
37 of the clinically characterized serum samples and 23 serum samples from apparently healthy donors were evaluated with the VIRGO® ß2Glycoprotein I IgG Antibody Kit, and a commercially available anti-cardiolipin IgG EIA assay. The results are summarized in the table below:
| aCL IgG | ||||
|---|---|---|---|---|
| IgG β₂ GPI | Positive | Positive24 | Negative2 | |
| Negative | 9 | 25 | ||
| TOTAL | 33 | 27 | ||
| Relative Sensitivity: | 72.7 %: {60.3 to 82.3 %; ₀.₉₅ Confidence Interval} | |||
| Relative Specificity: | 92.6 %: {83.1 to 97.0 %; ₀.₉₅ Confidence Interval} |
Relative Agreement: 81.7 %: { 70.2 to 89.5 %; 0.95 Confidence Interval}
{4}------------------------------------------------
Conclusion
The results of the both the comparative studies with the predicate device and the performance studies utilizing clinically characterized serum specimens support the claim that the proposed device is capable of effectively detecting IgG antibodies to ßycoprotein I in human serum.
510(k) Summary Page 5
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Image /page/5/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized caduceus symbol, which features a staff with a serpent entwined around it. The logo also includes the text "DEPARTMENT OF HEALTH & HUMAN SERVICES USA" arranged in a circular fashion around the caduceus symbol.
AUG 30 1999
Food and Drug Administration 2098 Gaither Road Rockville MD 20850
Mr. Joseph M. Califano Director, Regulatory Affairs Hemagen Diagnostics, Inc. 34-40 Bear Hill Road Waltham, Massachusetts 02154
Re: [K992224](https://510k.innolitics.com/device/K992224) Trade Name: VIRGO® ß, Glycoprotein I IgG Antibody Kit Regulatory Class: II Product Code: MSV Dated: June 14, 1999 Received: July 1, 1999
Dear Mr. Califano:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic OS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.
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Page 2
Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770) 488-7655.
This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification"(21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597, or at its internet address "http://www.fda.gov/cdrh/dsma/dsmamain.html".
Sincerely yours,
Steven Sutman
Steven I. Gutman, M.D, M.B.A. Director Division of Clinical Laboratory Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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#### VIRGO®ß,Glycoprotein I IgG Antibody Kit Device Name:
## Indication(s) For Use
This enzyme-linked immunosorbent assay (ELISA) is indicated for the detection and measurement of circulating IgG antibodies to ß2 Glycoprotein in human serum. The presence of these antibodies, in combination with clinical observations and other serological tests, can aid in the diagnosis of Primary and Secondary Antiphospholipid Syndrome.
# (PLEASE DO NOT WRITE BELOW THIS LINE)
Concurrence of CDRH, Office of Device Evaluation (ODE)
Peter E. Matin
(Division Sign-Off) Division of Clinical Laboratory Devices GG2224 510(k) Number -
Prescription Use
(Per 21 CFR 801.109) ✓
ーで
OR
Over-The-Counter-Use
§ 866.5660 Multiple autoantibodies immunological test system.
(a)
Identification. A multiple autoantibodies immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoantibodies (antibodies produced against the body's own tissues) in serum and other body fluids. Measurement of multiple autoantibodies aids in the diagnosis of autoimmune disorders (disease produced when the body's own tissues are injured by autoantibodies).(b)
Classification. Class II (performance standards).