IS-ANTI-SCL-70 TEST SYSTEM (720-280)

K970239 · Diamedix Corp. · LLL · Apr 8, 1997 · Immunology

Device Facts

• Record ID: K970239
• Device Name: IS-ANTI-SCL-70 TEST SYSTEM (720-280)
• 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 Scl-70 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-Scl-70 Test System is an ELISA kit for detecting IgG antibodies to Scl-70 antigen in human serum. Process: purified Scl-70 antigen coated on microtiter wells; patient serum added; incubation; wash; enzyme-labeled anti-human immunoglobulin conjugate added; incubation; wash; substrate solution added; colorimetric reaction measured photometrically. Output: photometric intensity providing indirect measure of specific antibody concentration. Used in clinical laboratories; performed manually or via MAGO automated system. Results aid clinicians in diagnosing autoimmune disorders by identifying presence of Scl-70 antibodies.

Clinical Evidence

Performance evaluated using 100 normal donor sera and 63 autoimmune patient sera. Manual method: 88% sensitivity, 100% specificity, 98% agreement. MAGO automated method: 92% sensitivity, 99% specificity, 98% agreement. Precision testing (intra/inter-assay CVs) and cross-reactivity studies (n=24) performed. Correlation between manual and MAGO methods was 0.99 (Pearson).

Technological Characteristics

Enzyme-linked immunosorbent assay (ELISA) using purified Scl-70 antigen coated on solid-phase microtiter wells. Employs enzyme-labeled anti-human immunoglobulin conjugate and substrate for colorimetric detection. Photometric measurement. Compatible with manual processing or MAGO automated system.

Indications for Use

Indicated for detection and semi-quantitation of IgG to Scl-70 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-Scl-70 Antibody Test Kit

Submission Summary (Full Text)

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K970239

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-Scl-70 Test System

Common Name: Anti-Scl-70 EIA Test

Classification Name: Extractable Antinuclear Antibody

## Equivalent Device:

Helix Diagnostics Enzyme Immunoassay Anti-Scl-70 Antibody Test Kit

## Device Description:

The Is-anti-Scl-70 Test Kit System is an enzyme-linked immunosorbent assay (ELISA) for the detection and semi-quantitation of IgG to Scl-70 antigen in human serum.

## Intended use:

The assay is intended for use in detecting antibodies to Scl-70 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-Scl-70 Test System is an enzyme-linked immunosorbent assay to detect IgG to Scl-70 in human serum. Purified Scl-70 antigen is attached to a solid phase microtiter well. Diluted test sera are added to each well. If antibodies which recognize the Scl-70 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-Scl-70 Test Kit was evaluated relative to another commercially available anti-Scl-70 ELISA test kit using 100 sera from normal blood donors and 63 sera from autoimmune patients. The results are summarized in Table 1 below.

| Table 1 | Manual | | | MAGO | | |
| --- | --- | --- | --- | --- | --- | --- |
| | Number of Sera | % | 95% Confidence | Number of Sera | % | 95% Confidence |
| Relative Sensitivity | 21/24 | 88 | 68-97 | 22/24 | 92 | 73-99 |
| Relative Specificity | 138/138 | 100 | 97-100 | 138/139 | 99 | 96-100 |
| Agreement | 159/162* | 98 | 95-100 | 160-163 | 98 | 95-100 |

* One equivocal sample was excluded from the calculations.

Three sera negative by Is-anti-Scl-70 (manual) and positive by the comparative method were negative when tested by a third method. Two sera negative by Is-anti-Scl-70 (MAGO) and positive by the comparative method were negative when tested by a third method. One serum positive by Is-anti-Scl-70 (MAGO) and negative by the comparative method was positive when tested by a third method. Two of the discordant sera were from patient samples.

## B. Linearity

Figures 1 and 2 show typical examples of Is-anti-Scl-70 Test Kit linearity. The figures depict the results of the Calibrator tested by Is-anti-Scl-70 after serial two-fold manual dilutions in Sample Diluent. Separate dilutions were tested both manually and with MAGO. The results demonstrate a high degree of linearity for the Is-anti-Scl-70 Test Kit throughout the testing range.

Figure 1 Manual Linearity

Figure 2 MAGO Linearity

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C. Precision Testing

The precision of the Is-anti-Scl-70 Test Kit was determined at Diamedix by testing six different sera and kit Calibrator and controls in two runs on three different days. The intra- and interassay precision is shown in Table 2 below.

| Table 2 | anti-Scl-70 PRECISION | | | | |
| --- | --- | --- | --- | --- | --- |
| SERUM | Overall MEAN EU/ml | MANUAL | | MAGO | |
| | | INTRA-CV% | INTER-CV% | INTRA-CV % | INTER-CV % |
| 1 (NEG) | 2.3 | 5.7 | 8.7 | 18.3 | 18.2 |
| 2 (NEG) | 3.9 | 5.8 | 10.3 | 12.4 | 13.2 |
| 3 (POS) | 50.5 | 3.1 | 5.0 | 1.8 | 5.4 |
| 4 (POS) | 29.0 | 4.3 | 4.4 | 5.3 | 9.4 |
| 5 (POS) | 79.6 | 2.7 | 4.5 | 2.1 | 3.5 |
| 6 (POS) | 103.1 | 1.8 | 3.6 | 4.7 | 6.1 |
| CAL | 106.0 | 5.4 | 7.3 | 3.3 | 6.7 |
| POS CTRL | 52.3 | 1.5 | 3.1 | 3.9 | 6.6 |
| NEG CTRL | 1.6 | 12.6 | 14.3 | 20.2 | 29.4 |

D. Crossreactivity

Twenty-four sera positive for the six autoimmune specificities were tested in Is- anti-Scl-70 Test Kit. The results are shown in Table 3.

Table 3 Crossreactivity

| Sample | Is-anti-Scl-70 EU/ml | Interp | Specificity |
| --- | --- | --- | --- |
| 1 | 7.2 | NEG | SSA |
| 2 | 3.7 | NEG | SSA |
| 3 | 1.5 | NEG | SSA |
| 4 | 3.0 | NEG | SSA |
| 5 | 4.0 | NEG | SSB |
| 6 | 2.6 | NEG | SSB |
| 7 | 3.1 | NEG | SSB |
| 8 | 3.6 | NEG | SSB |
| 9 | 3.0 | NEG | Sm |
| 10 | 3.2 | NEG | Sm |
| 11 | 2.5 | NEG | Sm |
| 12 | 4.1 | NEG | Sm |
| 13 | 4.4 | NEG | RNP |
| 14 | 3.0 | NEG | RNP |
| 15 | 4.2 | NEG | RNP |
| 16 | 4.7 | NEG | RNP |
| 17 | 3.3 | NEG | Jo-1 |
| 18 | 5.1 | NEG | Jo-1 |
| 19 | 1.9 | NEG | Jo-1 |
| 20 | 2.9 | NEG | Jo-1 |
| 21 | 134.2 | POS | Scl-70 |
| 22 | 108.0 | POS | Scl-70 |
| 23 | 110.1 | POS | Scl-70 |
| 24 | 165.6 | POS | 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 Sm results in the normal population performed manually and on MAGO respectively.

The distribution of EU/ml values for 50 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 150 samples in the Is-anti-Scl-70 Test Kit showed a correlation of 0.99 (Pearson).

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