RESEARCH - Autoantibodies in SLE: comparison and concurrent assessment of seropositivity

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ACR/ARHP 2008 Scientific Meeting

SLE: Clinical Aspects II

Monday, Oct 27, 2008, 9:00 AM - 6:00 PM

Presentation: 1062 - Autoantibodies in Systemic Lupus Erythematosus

(SLE): Comparison of Historical and Concurrent Assessment of

Seropositivity

Author(s): Petri1, Ippolito1, Lawrence Magder2,

SLICC. 1s Hopkins University, Baltimore, MD; 2University of

land, Baltimore, MD

Abstract: Introduction: Systemic lupus erythematosus (SLE) is

characterized by multiple autoantibodies and low complement. Anti-DNA

and low complement are well-known to improve with immunosuppressive

treatment. Past studies have shown that anti-ENA also fluctuates over

time. Many clinical trials require current autoantibody positivity for

enrollment. We sought to determine the correlation between historical

autoantibody tests and concurrent testing in patients with systemic

lupus erythematosus.

Methods: 302 SLE patients from the ACR Reclassification of SLE (AROSE)

database with both historical and concurrent laboratory data were

selected for analysis. The historical laboratory data were compared to

the reference laboratory (Rheumatology Diagnostic Laboratories, Los

Angeles, CA) autoantibody profile and tested for agreement using Kappa

statistic. Serologic tests included anti-dsDNA, anti-, Anti-RNP,

Anti-Ro, anti-La, rheumatoid factor, C3 and C4.

Results: There was good agreement between the historical and current

tests for anti-Ro, anti-La, anti-, and anti-RNP with Kappas of

69%, 61%, 55%, and 48%, respectively. The Kappa for anti-dsDNA by

Crithidia and FARR was only 24% and 25%, respectively. Rheumatoid

factor had a Kappa of 35%. Finally, low C4 had a Kappa of 34% and low

C3 demonstrated the least amount of correlation, with a Kappa of only

0.14%.

Conclusion: Our results categorize serologic tests into two groups,

those with good agreement over time (Ro, La, RNP, and Sm) and those

with poor agreement (anti-dsDNA, low complement, rheumatoid factor).

Variation in the tests could be partially explained by assay variation

or, in terms of complement levels, by genetic factors such as the null

allele. However, the clear differentiation into two groups suggests a

different immunopathology and response to treatment. We feel these

results have important implications for diagnosis, enrollment in

clinical trials, as well as for the diverse immunopathology of SLE.

Given the constancy of the anti-ENA autoantibodies, it may not be cost

effective to continually recheck these serologies during treatment.

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Not an MD