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.


Prevalence of Direct Coombs Test in Systemic Lupus Erythematosus. Clinical and Immunologic Associations.

Orbai1,  Ana-Maria, Fang1,  Hong, Alarcon2,  Graciela S., Gordon3,  Caroline, Merrill4,  Joan T., 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
University of Alabama at Birmingham, Birmingham, AL
UCSD School of Medicine, La Jolla, CA
North Dallas Dermatology Assoc, Dallas, TX
University of Maryland, Baltimore, MD
University of Birmingham, Birmingham, United Kingdom
Oklahoma Medical Research Foundation, Oklahoma City, OK
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:

To determine the prevalence of the direct Coombs in SLE and controls with other rheumatologic diseases, and to characterize its clinical associations.

Methods:

The Systemic Lupus International Collaborating Clinics Revision of SLE Classification Criteria derivation and validation datasets were merged for the purpose of this study. The analyses were based on 868 patients with both direct Coombs measured and physician consensus diagnosis available (456 SLE and 412 controls). Of the 456 SLE patients, 412 (90.4%) were female, 279 (61.2%) Caucasian, and 89 (19.5%) African descent. Their mean age was 37.7±13.4. The results were based on the chi-square test (SAS Institute, Cary, NC, USA). A p-value <=0.05 was considered statistically significant.

Results:

The prevalence of the positive direct Coombs test was 21% (96/456) in SLE patients and 6% (25/412) in controls (P-value <.0001), sensitivity 21%, and specificity 94% for SLE. Of 96 SLE patients with positive direct Coombs, 79 (82.3%) had never had hemolytic anemia.

Table 1. Association between Demographic Characteristics and Direct Coombs in SLE

Variable Positive Direct Coombs (%)P-value
EthnicityAfrican descent16.80.39
 Caucasian16.5 
 Asian25.0 
 Other12.5 
GenderFemale17.70.46
 Male13.6 
Age<=3021.10.15
 >3015.6 

Table 2. Association between ACR Criteria and Direct Coombs Status in SLE, Excluding Patients with Hemolytic Anemia

VariablePositive Direct Coombs (%)Negative Direct Coombs (%)Odds Ratio (95% CI)P-value
Malar Rash40.542.70.9 (0.6, 1.5)0.72
Discoid Rash12.718.30.6 (0.3, 1.3)0.23
Photosensitivity41.849.10.7 (0.5, 1.2)0.24
Oral Ulcers39.240.31.0 (0.6, 1.6)0.86
Arthritis69.661.31.4 (0.9, 2.4)0.16
Serositis36.731.81.2 (0.7, 2.1)0.40
Pleurisy32.925.21.5 (0.9, 2.5)0.16
Pericarditis15.212.21.3 (0.6, 2.6)0.47
Renal criterion36.734.21.1 (0.7, 1.8)0.67
Neurologic10.16.41.7 (0.7, 3.8)0.23
Hematologic60.847.51.7 (1.0, 2.8)0.032
Leukopenia36.726.81.6 (0.9, 2.6)0.08
Lymphopenia34.228.11.3 (0.8, 2.2)0.28
Thrombocytopenia21.513.81.7 (0.9, 3.2)0.08
Immunologic94.981.24.4 (1.5, 12.3)0.0027
Anti-dsDNA7662.11.9 (1.1, 3.4)0.02
Anti-Smith34.223.61.5 (0.9, 2.8)0.049
Antiphospholipid64.652.81.6 (0.9, 2.7)0.055
Anticardiolipin IgG27.9171.9 (1.1, 3.3)0.025
Low complement8160.52.8 (1.5, 5.1)0.0005

Conclusion:

The great majority of patients with SLE and a positive direct Coombs had never had hemolytic anemia. A positive direct Coombs test was highly associated with SLE versus other rheumatologic diseases. It was associated with the ACR hematologic criterion, anti-dsDNA, anti-Smith, anticardiolipin IgG and low complement. These data justify the decision by SLICC to include direct Coombs in the new classification criteria for SLE.

To cite this abstract, please use the following information:
Orbai, Ana-Maria, Fang, Hong, Alarcon, Graciela S., Gordon, Caroline, Merrill, Joan T., Fortin, Paul R., et al; Prevalence of Direct Coombs Test in Systemic Lupus Erythematosus. Clinical and Immunologic Associations. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1383
DOI:

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