Background/Purpose: Giant cell arteritis (GCA) is the most common form of vasculitis in patients over the age of 50. Interleukin-6 (IL-6) has been shown to play a potential role in the pathogenesis and prognosis of GCA, becoming a key therapeutic target. Moreover, some studies have suggested a potential prognostic value. This study explores the association between baseline IL-6 concentrations and the clinical phenotype of the disease, with the aim of identifying patients who may benefit from anti–IL-6 therapies.

Methods: We conducted a cross-sectional study of a cohort of patients diagnosed with GCA between 2020 and 2024 in a tertiary care hospital. Patients were classified into two groups: those with exclusively cranial involvement (cranial GCA) and those with extracranial fluorodeoxyglucose (FDG) uptake at a PET-CT scan with or without cranial involvement (extracranial/mixed GCA).A multiple linear regression model was used to evaluate the association between IL-6 levels and the clinical phenotype of GCA, adjusting for potential confounding and interaction variables (age, BMI, smoking status, type 2 diabetes mellitus, and prior corticosteroid therapy).Regression coefficients (β), 95% confidence intervals (95% CI), and p-values were calculated, using a significance threshold of p < 0.05.Model fit was assessed using the adjusted R-squared (adjusted R²) and the F-test.

Results: A total of 39 patients were included. Epidemiological, clinical and diagnostic variables are detailed in Table 1. In the multiple regression analysis, no significant association was found between IL-6 levels and clinical phenotype (p = 0.673).A significant negative association was observed between IL-6 levels and age (β = -1.059, 95% CI: -1.741 to -0.376, p = 0.003), as well as between IL-6 le levels and prior corticosteroid therapy (β = -16.398, 95% CI: -26.709 to -6.086, p = 0.003).A significant positive correlation was found between IL-6 and CRP (r = 0.4546, p = 0.0032) and between IL-6 and ESR (r = 0.3754, p = 0.0185).Other clinical and diagnostic variables did not reach statistical significance.

Conclusion: In our cohort, no significant association was found between IL-6 levels and the clinical phenotype of GCA. Patients with constitutional symptoms and PMR tended to have higher IL-6 levels, which may suggest a greater inflammatory burden—an observation that should be confirmed in studies with larger sample sizes. Notably, IL-6 levels were inversely associated with age, a finding that contrasts with current literature and may open new avenues for research.This study reinforces the importance of further exploring the role of IL-6 to identify patients who may benefit most from targeted therapy against this molecule.*The first two authors contributed equally to this abstract.

Table 1. Patient’s epidemiological, clinical, and diagnostic characteristics.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-baseline-il-6-levels-and-the-clinical-phenotype-of-giant-cell-arteritis/