AB1004 EPIDEMIOLOGY AND RISK FACTORS OF CUTANEOUS VASCULITIS IN SYSTEMIC LUPUS ERYTHEMATOSUS: INSIGHTS FROM A 20-YEAR LONGITUDINAL STUDY
Authors: A. Saleh, C. Gordon, J. Reynolds
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Cutaneous vasculitis (CV) is the most common form of vasculitis observed in patients with SLE, however the precise epidemiological trends and underlying risk factors remain unclear. According to the classic BILAG index, CV is classified into i) major CV, which includes ulcerations with infarction, and ii) minor CV, which includes nailfold vasculitis, digital vasculitis, purpura, and urticaria. <h3>Objectives:</h3> The aim of this study was to identify the changes in epidemiology and the potential risk factors of CV in systemic lupus erythematosus (SLE) patients over a period of 20 years. <h3>Methods:</h3> The Birmingham Lupus Cohort is a longitudinal observational cohort of patients with SLE. All patients fulfilled the 1997 ACR Updated Classification Criteria for SLE. Inception patients were recruited within 3 years of their fourth ACR criterion. Disease activity was assessed using the classic BILAG index, and laboratory results and medications were recorded. The BILAG vascular domain was used to determine the incidence rate, which refers to the rate at which new cases of minor and major CV attributed to active SLE occur. A multivariable Cox proportional hazard frailty model was developed to identify clinical, laboratory, and treatment variables associated with the development of CV. <h3>Results:</h3> We analysed 392 patients, of whom 375 (92.5%) were females. There were 213 (55.0%) White, 72 (18.6%) African-Caribbean, 82 (21.1%) South Asian, 9 (2.3%) East Asian, and 11 (2.8%) other ethnicities. The median (IQR) age at enrolment was 33 (26 - 44) years and the median duration of follow up was 9.2 (5.1 - 14.7) years. Within the 1<sup>st</sup> 3 years following enrollment the incidence rate of minor CV was 106.5 (95% CI: 88.9, 127.5) per 1000 person-years; however, after 18 years of follow-up, the incidence rate decreased to 7.6 (95% CI: 0.1, 54.1) per 1000 person-years. Similarly, the incidence rate of major CV was at 16.2 (95% CI: 10.2, 25.7) per 1000 person-years in the first three years and then decreased to 2.8 (95% CI: 0.3, 20.1) per 1000 person-years between 12 and 15 years of follow-up (Table 1). In the Cox proportional hazard model, there was a positive association between CV and Raynaud's phenomenon (hazard ratio [HR] 3.37 [95% CI: 2.40, 4.72]), and general (HR 2.42 [95% CI: 1.43, 4.29]), mucocutaneous (HR 2.23 [95% CI: 1.56, 3.18]), musculoskeletal (HR 1.85 [95% CI: 1.28, 2.68]), and haematological (HR 1.76 [95% CI: 1.21, 2.54]) domains of the classic BILAG index. In addition, CV was positively associated with anti-dsDNA (HR 1.46 [95% CI: 1.04, 2.04]), anti-Sm antibodies (HR 2.36 [95% CI: 1.31, 4.24]), and hypocomplementemia (HR 1.86 [95% CI: 1.32, 2.62]). However, there was a negative association between CV and the use of methotrexate (HR 0.38 [95% CI: 0.14, 1.03]), azathioprine (HR 0.60 [95% CI: 0.41, 0.87]), and hydroxychloroquine (HR 0.65 [95% CI: 0.47, 0.92]), suggesting a protective effect. <h3>Conclusion:</h3> The incidence of CV decreases over follow-up. CV is associated with defined clinical and serological features and occurs in the context of overall increased lupus disease activity. Treatment with methotrexate, azathioprine, and hydroxychloroquine may reduce the risk of developing CV. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>