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.


Cluster Analysis of Autoantibodies in 852 Patients with Systemic Lupus Erythematosus From a Single Center: Four Main Clusters with Prognostic Implications.

Artim-Esen1,  Bahar, Cene2,  Erhan, Sahinkaya1,  Yasemin, Ertan1,  Semra, Pehlivan1,  Özlem, Kamali1,  Sevil, Gul1,  Ahmet

Istanbul Faculty of Medicine, Department of Internal Medicine, Division of Rheumatology, Istanbul, Turkey
Yildiz Technical University, Department of Statistics, Faculty of Arts and Sciences, Istanbul, Turkey

Background/Purpose:

Systemic Lupus Erythematosus (SLE) is an autoimmune disease with various serological and clinical manifestations. Associations between autoantibodies and clinical features have been described. Herein, we aimed to define autoantibody clusters and their clinical correlations in a large cohort of lupus patients.

Methods:

We analysed 852 patients who attended our clinic (lupus clinic after 1993) between 1980 and 2010. Mean duration of disease was 115±85,9 months and 87% was female. Seven autoantibodies, namely anti-DNA, anti-Sm, anti-RNP, anticardiolipin IgG or IgM (aCL IgG/M), Lupus anticoagulant (LAC), anti-Ro, anti-La were selected for cluster analysis to identify subsets of lupus patients with similar autoantibody patterns. K-means cluster and Kaplan-Meier survival analyses were used.

Results:

The frequencies of the selected autoantibodies in the cohort were as follows: anti-dsDNA 70%, anti-Sm 19%, anti-RNP 15%, Anti-Ro 24%, anti-La 11%, LAC 11%, aCL IgG/M 29%. Four clusters were identified by cluster analysis. Cluster 1 consisted of anti-Sm and anti-RNP, cluster 2 of anti-dsDNA only, cluster 3 of anti-Ro and anti-La and cluster 4 of aCL IgG/M autoantibodies. Although it did not reach statistical significance, LAC was more prevalent in cluster 4. Patients in cluster 1 when compared to 3 other clusters had significantly higher incidence of pulmonary hypertension (11%) and lower incidence of renal (12%) and neuropsychiatric involvement (7,9%). Cluster 2 had the highest incidence of renal involvement (43,2%) with diffuse proliferative nephritis dominating. In cluster 4, there were significantly more patients with neuropsychiatric involvement (42,9%), arterial (53,6%) and venous (54%) thrombotic events and autoimmune hemolytic anemia (33,3%). According to SLICC damage index, the highest frequency of damage was in cluster 2 (32,7%). Among SLICC damage items, there were significantly more patients with renal damage (43,1%) in cluster 2 compared to other clusters (11,1%, 15,3% and 30,6% in clusters 1, 3 and 4 respectively). Patients in cluster 4 had the highest percentage of damage due to arterial and/or venous thrombotic events. This cluster also had significantly more neuropsychiatric (40,2%) and cardiovascular (32,6%) damage compared to 3 other clusters. Comparison of 10 (98%, 92%, 95%, 88%) and 20 (98%, 87%, 88%, 80%) years survival in four clusters shows a trend towards reduced survival in Cluster 4 but the analysis did not reveal any statistical difference.

Table 1. Frequency of autoantibodies in clusters, n (%)

AutoantibodyCluster 1 (n=136)Cluster 2 (n=293)Cluster 3 (n=240)Cluster 4 (n=183)
Anti dsDNA69 (50,7)293 (100)*98(40,8)141 (77)
Anti Sm135 (99,2)*9 (3)14 (5,8)5 (2,7)
Acl IgG/IgM43 (31,6)0 (0)21 (8,7)183 (100)*
LAC12 (8,8)10 (4)15 (6,2)55 (30)
Anti RNP121 (88,9)*2 (0,8)4 (1,6)4 (2,1)
Anti RO36 (26,4)0 (0)152 (63,3)*17 (9,2)
Anti LA14 (10,2)2 (0,8)71 (29,5)*4 (2,1)

Conclusion:

This study confirms the prognostic importance of autoantibodies and shows that disease subsetting according to autoantibody clusters may be useful in predicting the outcome of the disease. The cluster with only anti-dsDNA positivity in the absence of other important autoantibodies carries the highest risk for a major organ involvement and damage in our cohort.

To cite this abstract, please use the following information:
Artim-Esen, Bahar, Cene, Erhan, Sahinkaya, Yasemin, Ertan, Semra, Pehlivan, Özlem, Kamali, Sevil, et al; Cluster Analysis of Autoantibodies in 852 Patients with Systemic Lupus Erythematosus From a Single Center: Four Main Clusters with Prognostic Implications. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :2305
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