Phenotypic heterogeneity of giant cell arteritis in an Asian cohort: clinical, imaging, and laboratory characteristics.

Giant cell arteritis (GCA) exhibits phenotypic heterogeneity. The diagnosis of large vessel involvement in GCA remains challenging, and conventional inflammatory markers have limitations. This study aimed to characterize phenotypic profiles and explore the role of novel hematological indices in an Asian cohort. This single-center retrospective study enrolled 110 patients diagnosed with GCA between 2015 and 2025. Patients were classified into cranial (cGCA), mixed (mixGCA), and isolated large-vessel (LV-GCA) phenotypes. Demographics, clinical features, and laboratory parameters-including the systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and serum albumin-were analyzed. The performance of the 1990 ACR and 2022 ACR/EULAR classification criteria was evaluated. The cohort comprised 110 patients (65 men, 59.1%; 45 women, 40.9%), and was divided into cGCA (44.5%), mixGCA (36.4%), and LV-GCA (19.1%). LV-GCA presented with more constitutional symptoms and limb claudication but fewer cranial symptoms. Novel hematological indices, particularly SII and PLR, showed significant positive correlations with C-reactive protein levels. Multivariate logistic regression analysis revealed that serum albumin level was independently associated with large-vessel involvement (LVI; OR = 0.865, 95% CI [0.767-0.974], p = 0.017). The 2022 ACR/EULAR criteria had higher overall sensitivity (77.3%) than the 1990 ACR criteria (69.1%). GCA presents a distinct clinical profile in this Asian cohort. Novel hematological indices (including SII and PLR) correlate with acute-phase reactants, and serum albumin is associated with LVI. These preliminary findings suggest that these biomarkers, alongside lower-limb arterial ultrasound, may aid in identifying LVI, requiring prospective validation.