IS-ANTI-SSB TEST SYSTEM (720-260)

K970237 · Diamedix Corp. · LLL · Apr 8, 1997 · Immunology

Device Facts

• Record ID: K970237
• Device Name: IS-ANTI-SSB TEST SYSTEM (720-260)
• Applicant: Diamedix Corp.
• Product Code: LLL · Immunology
• Decision Date: Apr 8, 1997
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.5100
• Device Class: Class 2

Intended Use

The assay is intended for use in detecting antibodies to SSB (La) antigen in a single human serum sample. The results of the assay are to be used as an aid in the diagnosis of autoimmune disorders.

Device Story

Is-anti-SSB Test System is an ELISA for detecting/semi-quantitating IgG to SSB (La) antigen in human serum. Purified SSB (La) antigen is immobilized on microtiter wells. Patient serum is added; if anti-SSB antibodies are present, they bind to the antigen. After washing, enzyme-labeled anti-human immunoglobulin conjugate is added, followed by a substrate solution. Enzyme activity converts substrate to a colored product. Color intensity is measured photometrically, providing an indirect measure of specific antibody concentration. Used in clinical laboratories; performed manually or via the MAGO automated system. Results assist clinicians in diagnosing autoimmune disorders.

Clinical Evidence

Performance evaluated using 165 sera (100 normal, 65 autoimmune). Compared to a commercial anti-SSB ELISA, the device showed 95% relative sensitivity (95% CI: 83-99%) and 100% relative specificity (95% CI: 97-100%). Agreement was 99%. Precision (intra- and inter-assay CVs) and linearity were assessed. Cross-reactivity testing on 24 sera positive for other autoimmune specificities (SSA, Sm, RNP, Jo-1, Scl-70) showed no significant interference.

Technological Characteristics

Enzyme-linked immunosorbent assay (ELISA). Solid phase: microtiter wells coated with purified SSB (La) antigen. Detection: enzyme-labeled anti-human immunoglobulin conjugate and substrate. Measurement: photometric color intensity. Compatible with manual processing or the MAGO automated system. Connectivity: standalone or integrated with MAGO processor.

Indications for Use

Indicated for detection and semi-quantitation of IgG to SSB (La) antigen in human serum to aid in the diagnosis of autoimmune disorders.

Regulatory Classification

Identification

An antinuclear antibody immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoimmune antibodies in serum, other body fluids, and tissues that react with cellular nuclear constituents (molecules present in the nucleus of a cell, such as ribonucleic acid, deoxyribonucleic acid, or nuclear proteins). The measurements aid in the diagnosis of systemic lupus erythematosus (a multisystem autoimmune disease in which antibodies attack the victim's own tissues), hepatitis (a liver disease), rheumatoid arthritis, Sjögren's syndrome (arthritis with inflammation of the eye, eyelid, and salivary glands), and systemic sclerosis (chronic hardening and shrinking of many body tissues).

Predicate Devices

• Helix Diagnostics Enzyme Immunoassay Anti-SS-B/La Antibody Test Kit

Submission Summary (Full Text)

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K910237

APR - 8 1997

# 510(k) Summary of Safety and Effectiveness

This summary of safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.

The assigned 510(k) number is: ________________

## Applicant Information:

Date Prepared: January 15, 1997

Name: Diamedix Corporation

Address: 2140 N. Miami Avenue

Miami, FL 33127

Contact Person: Dr. Lynne Stirling

Phone Number: 305-324-2354

Fax Number: 305-324-2585

## Device Information:

Trade Name: Is-(immunosimplicity)-anti-SSB Test System

Common Name: Anti-SSB EIA Test

Classification Name: Extractable Antinuclear Antibody

## Equivalent Device:

Helix Diagnostics Enzyme Immunoassay Anti-SS-B/La Antibody Test Kit

## Device Description:

The Is-anti-SSB Test Kit System is an enzyme-linked immunosorbent assay (ELISA) for the detection and semi-quantitation of IgG to SSB (La) antigen in human serum.

## Intended use:

The assay is intended for use in detecting antibodies to SSB (La) antigen in a single human serum sample. The results of the assay are to be used as an aid in the diagnosis of autoimmune disorders.

## Comparison to Predicate Device:

The Is-anti-SSB Test System is an enzyme-linked immunosorbent assay to detect IgG to SSB (La) in human serum. Purified SSB (La) antigen is attached to a solid phase microtiter well. Diluted test sera are added to each well. If antibodies which recognize the SSB antigen are present in the patient sample, they will bind to the antigen in the well. After incubation, the wells are washed to remove unbound antibody. An enzyme-labeled anti-human immunoglobulin (conjugate) is added to each test well. If antibody is present the enzyme-linked antibody will bind to it. After incubation, the wells are washed to remove unbound conjugate. A substrate solution is then added to each well. If enzyme is present from the prior step, the substrate will be converted to produce a colored product. The reaction is stopped and the color intensity is measured photometrically providing an indirect measure of the specific antibody present in the patient sample.

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Summary of Safety and Effectiveness

## Performance Characteristics

### A. Comparison Testing

The Diamedix Is-anti-SSB Test Kit was evaluated relative to another commercially available anti-SSB ELISA test kit using clinically characterized sera. One hundred sera from normal blood donors and 65 sera from autoimmune patients were tested by Is-anti-SSB and a commercially obtained anti-SSB ELISA test kit. The results are summarized in Table 1. below.

| Table 1 | Manual | | | MAGO | | |
| --- | --- | --- | --- | --- | --- | --- |
| | Number of Sera | % | 95% Confidence | Number of Sera | % | 95% Confidence |
| Relative Sensitivity | 38/40 | 95 | 83-99 | 38/40 | 95 | 83-99 |
| Relative Specificity | 124/124 | 100 | 97-100 | 124/124 | 100 | 97-100 |
| Agreement | 162/164* | 99 | 96-100 | 162/164* | 99 | 96-100 |

* One borderline sample was excluded from the calculation.

Two sera were negative in Is-anti-SSB and positive in the comparative method (manual and MAGO). Upon retest by a referee method, one of the sera was positive, the other was negative.

### B. Linearity

Figures 1 and 2 show typical examples of Is-anti-SSB Test Kit linearity. The figures depict the results of the Calibrator tested by Is-anti-SSB after a serial two-fold manual dilution in Sample Diluent. Separate dilutions were tested both manually and with MAGO. The results demonstrate a high degree of linearity for the Is-anti-SSA Test Kit throughout the testing range.

Figure 1. Manual Linearity

Figure 2. MAGO Linearity

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# C. Precision

The precision of the Is-anti-SSB Test Kit was determined by testing six different sera and kit Calibrator and controls in two runs on three different days. The intra- and inter assay precision is shown in Table 2.

| SERUM | OVERALL MEAN EU/ml | MANUAL INTRA-CV% INTER-CV% | | MAGO INTRA-CV % INTER-CV% | |
| --- | --- | --- | --- | --- | --- |
| 1 (NEG) | 1.4 | 10.1 | 21.4 | 27.3 | 30.8 |
| 2 (NEG) | 1.4 | 4.3 | 6.3 | 13.9 | 16.7 |
| 3 (POS) | 37.5 | 4.5 | 11.2 | 8.2 | 11.2 |
| 4 (POS) | 29.7 | 4.1 | 10.4 | 4.1 | 9.2 |
| 5 (POS) | 55.4 | 4.0 | 8.0 | 4.0 | 8.3 |
| 6 (POS) | 96.9 | 3.5 | 5.3 | 3.0 | 8.7 |
| CAL | 100.8 | 4.2 | 6.5 | 5.6 | 10.1 |
| POS CTRL | 39.8 | 2.5 | 8.5 | 4.5 | 11.3 |
| NEG CTRL | 0.9 | 10.3 | 30.0 | 53.0 | 50.0 |

# D. Crossreactivity

Twenty-four sera positive for the six autoimmune specificities were tested in Is-anti-SSB Test Kit. The results are shown in Table 3

| Sample | Is-anti-SSB EU/ml | Interp | Specificity |
| --- | --- | --- | --- |
| 1 | 5.5 | Neg | SSA |
| 2 | 3.7 | Neg | SSA |
| 3 | 0.9 | Neg | SSA |
| 4 | 1.6 | Neg | SSA |
| 5 | 236.2 | Pos | SSB |
| 6 | 48.3 | Pos | SSB |
| 7 | 148.3 | Pos | SSB |
| 8 | 128.4 | Pos | SSB |
| 9 | 6.3 | Neg | Sm |
| 10 | 1.4 | Neg | Sm |
| 11 | 1.1 | Neg | Sm |
| 12 | 1.6 | Neg | Sm |
| 13 | 3.7 | Neg | RNP |
| 14 | 2.1 | Neg | RNP |
| 15 | 2.3 | Neg | RNP |
| 16 | 3.3 | Neg | RNP |
| 17 | 1.4 | Neg | Jo-1 |
| 18 | 4.5 | Neg | Jo-1 |
| 19 | 1.5 | Neg | Jo-1 |
| 20 | 1.7 | Neg | Jo-1 |
| 21 | 2.1 | Neg | Scl-70 |
| 22 | 2.5 | Neg | Scl-70 |
| 23 | 2.3 | Neg | Scl-70 |
| 24 | 1.8 | Neg | Scl-70 |

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# E. Expected Values

The expected values in the normal population were determined by assaying 100 normal donor sera collected in South Florida. Figures 3 and 5 show the distribution of SSB results in the normal population performed manually and on MAGO respectively.

The distribution of EU/ml values for 65 clinically characterized sera along with the 100 normal donor sera are shown in Figures 4 and 6 performed manually and on MAGO respectively.

Figure 3. Manual Normals

Figure 4. Manual Expected Values

Figure 5 MAGO Normals

Figure 6. MAGO Expected Values

# F. Correlation of Manual and MAGO Results

Numerical comparison of EU/ml values, between manual and MAGO results for 165 samples in the Is-anti-SSB Test Kit showed a correlation of 0.91 (Pearson).

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