APPLICATION OF CLUSTER ANALYSIS TO IDENTIFY DISEASE PHENOTYPE ASSOCIATED WITH EROSIVE ARTHRITIS IN SYSTEMIC LUPUS ERYTHEMATOSUS
- Francesco Natalucci (Italy)
Abstract
Background and Aims
The definition of Systemic Lupus Erythematosus (SLE) related arthritis have been substantially changed due to the application of more sensitive imaging techniques. Thus, erosive arthritis could be identified in 40% of patients, suggesting the need for specific biomarkers. In this view, ACPA and anti-CarP have been associated with erosive damage; furthermore, the role of Dkk-1 was suggested. We used Cluster Analysis (CA) to identify different clinical and laboratory features associated with erosive arthritis.
Methods
We enrolled patients with a clinical history of joint involvement, evaluating the presence of erosive arthritis by hands ultrasound. Clinical and laboratory data were collected, including Rheumatoid Factor (RF), ACPA, anti-CarP, Dkk-1 levels. An unsupervised hierarchical CA was performed (SPSS 26 version) to identify the aggregation of patients into different subgroups sharing common features.
Results
One hundred twelve patients (M/F 6/106; median age 45 years, IQR 17; median disease duration 96 months, IQR 165) were analyzed. Erosive arthritis was identified in 25.9% of patients; RF was positive in 31.2% of patients, anti-CarP in 23.2%, ACPA in 8%, detectable Dkk-1 in 6.2%. CA for clinical characteristics identified four defined clusters (figure 1). Interestingly, in the same cluster were allocated ACPA and anti-CarP positivity, detectable Dkk-1 levels, erosive arthritis and renal manifestations. RF resulted allocated in a different cluster, including anti-SSA and anti-SSB.
Conclusions
CA identified a specific SLE phenotype with erosive arthritis, renal manifestations, anti-CarP and ACPA positivity and detectable Dkk-1. We could speculate about the presence of a shared pathogenic mechanism, involving NETosis, contributing to nephritis and erosive arthritis.