Comparison of biopsy-proven giant cell arteritis in North America and Southern Europe: a population-based study.

To compare clinical characteristics, treatment and prognosis of two population-based cohorts of patients with biopsy-proven giant cell arteritis (GCA) from Olmsted County, Minnesota, USA (Olmsted cohort) and the Reggio Emilia area, Northern Italy (Reggio cohort).All patients residing in Olmsted County and the Reggio Emilia area with a new diagnosis of biopsy-proven GCA in 1986-2007 were retrospectively identified. Patients were followed from GCA...