Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Anti-beta2 Glycoprotein I IgA in Systemic Lupus Erythematosus Versus Controls.

Orbai1,  Ana-Maria, Fang1,  Hong, Merrill2,  Joan T., Alarcon3,  Graciela S., Gordon4,  Caroline, Fortin5,  Paul R., Bruce6,  Ian N.

Johns Hopkins University School of Medicine, Baltimore, MD
University Hospital Lund, Lund, Sweden
Northwestern University Feinberg School of Medicine, Chicago, IL
Hanyang University Hospital for Rheumatic Diseases, Clinical Research Center for Rheumatoid Arthritis (CRCRA), Seoul, South Korea
Dalhousie University, Halifax, NS
University Health Network/Mount Sinai Hospital, Toronto, ON
Research Institute of the McGill Univ. Health, Montreal, QC
Feinstein Institute for Medical Research, Manhasset, NY
Allegheny Singer Research Institute, Pittsburgh, PA
Toronto Western Hospital and University of Toronto, Toronto, ON
Toronto Western Research Institute, University of Toronto, University Health Network, Toronto, ON
Oklahoma Medical Research Foundation, Oklahoma City, OK
UCSD School of Medicine, La Jolla, CA
North Dallas Dermatology Assoc, Dallas, TX
University of Maryland, Baltimore, MD
3University of Alabama at Birmingham, Birmingham, AL
University of Birmingham, Birmingham, United Kingdom
Toronto Western Hospital, Toronto, ON
A, Manchester, United Kingdom
University College London, London WC1E 6JF, United Kingdom
Cedars-Sinai/UCLA, Los Angeles, CA
University Hospital, Lund, Sweden

Background/Purpose:

Anti-beta2 glycoprotein I (GPI) is not part of the ACR classification criteria for SLE, and IgA isotypes are omitted from the classification criteria for APS. We studied the prevalence and associations of anti-beta2 glycoprotein I IgA in a large multi-center study.

Methods:

The dataset consisted of 1384 patients with both anti-beta2-GPI IgA measured and a consensus physicians diagnosis (657 with SLE and 727 controls with other rheumatologic diseases). Of the 657 SLE patients, 599 (91%) were female, 394 (60%) were Caucasian, 134 (20%) were of African descent, and 76 (12%) were Asian. Their mean age (years) was 37.9±13.3. P-values were calculated based on the chi-square test (SAS Institute, Cary, NC, USA).

Results:

The prevalence of anti-beta2-GPI IgA was 14% (94/657) in SLE patients and 7% (49/727) in controls (P-value<0.0001, OR=2.3 (95% CI: 1.6, 3.3)). Eleven percent (73/657) of SLE patients had anti-beta2-GPI IgA alone (no anti-beta2-GPI IgG or IgM).

Table 1: Percentage of SLE Patients with Anti-beta2-GPI IgA, by Demographic Variables

  Percentage with Anti-beta2-GPI IgAP-value
EthnicityAfrican Descent21.60.019
 Caucasian11.4 
 Asian18.4 
 Other11.3 
GenderFemale14.20.78
 Male15.5 
Age<=3020.30.0035
 >3011.7 

Table 2: Percentage of SLE Patients with Various Clinical Conditions, by Anti-beta2-GPI IgA Status

ACR criteriaAnti-beta2-GPI IgA (%)No Anti-beta2-GPI IgA (%)P-valueOdds Ratio (95% CI)Adjusted P-value for Race and Age
Malar Rash52.143.50.121.4 (0.9, 2.2)0.16
Discoid Rash20.217.90.601.3 (0.7, 2.2)0.42
Photosensitivity48.951.00.711.0 (0.6, 1.5)0.91
Oral Ulcers38.341.60.550.9 (0.6, 1.4)0.57
Arthritis66.065.90.991.0 (0.6, 1.6)0.93
Serositis38.330.90.151.3 (0.8, 2.0)0.33
Pleurisy34.025.40.081.4 (0.9, 2.3)0.16
Pericarditis12.810.80.580.9 (0.5, 1.9)0.86
Renal39.431.10.111.1 (0.7, 1.8)0.63
Proteinuria37.230.00.161.1 (0.7, 1.8)0.71
Urinary casts9.67.10.401.1 (0.5, 2.5)0.73
Neurologic6.47.10.800.8 (0.3, 2.1)0.72
Seizure5.35.50.941.0 (0.4, 2.6)0.92
Psychosis3.22.00.441.5 (0.4, 5.8)0.54
Hematologic lupus61.749.70.0321.5 (0.9, 2.4)0.09
Leukopenia35.128.40.191.2 (0.7, 1.9)0.56
Lymphopenia29.830.90.830.9 (0.6, 1.5)0.72
Thrombocytopenia18.114.00.301.2 (0.7, 2.3)0.46
Anti-dsDNA75.557.00.00072.4 (1.4, 4.1)0.001
Anti-Smith25.523.60.690.8 (0.5, 1.4)0.51
Lupus anticoagulant70.248.90.00012.4 (1.5, 3.9)0.0003
Anticardiolipin IgG40.416.2<.00013.0 (1.9, 5.0)<.0001
Anticardiolipin IgM35.111.6<.00014.0 (2.4, 6.7)<.0001
Anticardiolipin IgA8.50.9<.000110.8 (3.2, 36.8)0.0001
False positive RPR9.63.40.0323.3 (1.1, 10.1)0.033

Table 3: Sensitivity and Specificity for SLE, based on Anti-beta2 Glycoprotein I IgA Positivity

 Sensitivity %Specificity %
Anti-beta2-GPI IgA14.393.3

Conclusion:

Anti-beta2 glycoprotein I IgA was more prevalent in SLE patients (14%) than in patients with other rheumatologic diseases (7%) in this international multi-center study. It can occur as the sole isotype of anti-beta2-GPI in SLE. It was strongly associated with age, anti-dsDNA and other antiphospholipid antibodies and was highly specific for SLE. This was the rationale to include anti-beta2 glycoprotein I IgA in the new SLICC classification criteria for SLE.

To cite this abstract, please use the following information:
Orbai, Ana-Maria, Fang, Hong, Merrill, Joan T., Alarcon, Graciela S., Gordon, Caroline, Fortin, Paul R., et al; Anti-beta2 Glycoprotein I IgA in Systemic Lupus Erythematosus Versus Controls. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :4
DOI:

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