Association between histological features and clinical features of patients with biopsy positive giant cell arteritis

Objective. The aim of this study was to investigate the association between histological biopsy features and clinical features, such as blindness, in patients with biopsy positive giant cell arteritis (GCA). Methods. Positive temporal artery biopsies registered on the South Australian Giant Cell Arteritis Registry were identified between 1991 and 2013 (n=186). Clinical and serological data was recorded using both patient questionnaire and case note review. Patients without clinical data were excluded from the analysis (n=42). Statistical analysis was performed using chi-squared and Wilcoxon's tests. Results. 144 biopsy positive GCA cases were analysed. The mean age at biopsy was 77 years; 71% were female. In total 25% experienced blindness. Although not individually significant, transmural inflammation (p=0.11), luminal thrombus (p=0.17) and giant cells (p=0.20) were more frequent in patients who suffered blindness, whereas fragmentation of the internal elastic lamina (p=0.04), and intimal thickening (p=0.02) were more frequent in patients without blindness. The presence of giant cells was associated with transmural inflammation (p=0.06), jaw claudication (p=0.02), and higher inflammatory markers. In contrast, characteristics of patients with intimal thickening included a lower frequency of giant cells (0.01) and jaw claudication (p=0.01), and lower inflammatory markers. Conclusion. Giant cells are strongly associated with jaw claudication and systemic markers of inflammation, perhaps reflecting more acute and aggressive disease. We did not find any histological features that were individually significantly associated with an increased risk of blindness in GCA patients.