Treatment and risk of relapse in GCA in Western Norway 2013-2020: a retrospective cohort study.

Objectives: During recent decades, there has been a growing recognition of the spectrum of GCA. This study aims to identify predictors of variation in the initial treatment of GCA and compare the relapse risk among patients with four different clinical phenotypes using a cohort of 256 well-defined GCA patients in Western Norway. Methods: Regression models were used to identify predictors of differences in initial oral glucocorticoid (GC) dosage and for the administration of intravenous GC (IVGC). Tapering of GCs was analysed using a linear mixed effects model. Time to GC discontinuation, end of rheumatological follow-up, and relapse were assessed with Kaplan-Meier methods and Cox regression. Results: Patients with cranial phenotype had lower risk of relapse, were more likely to discontinue GC treatment, and had shorter follow-up time at the rheumatological department compared with patients with other phenotypes. Neither the initial GC treatment nor GC tapering differed between the phenotypes. The only factor strongly associated with more intensive initial treatment was visual disturbances. Conclusions: Patients with the cranial GCA phenotype seem to have a shorter and less complicated disease course compared with patients with other phenotypes. This could suggest that early phenotype identification can yield important prognostic information.