Giant cell arteritis in Finland from 2010 to 2020: incidence, developing diagnostic methods and disease presentation.

Abstract

Objectives: To study the annual incidence, diagnostic methods used and clinical presentation of giant cell arteritis (GCA) over time in Finland.

Methods: Newly diagnosed GCA patients from 2010 to 2020 were retrospectively identified from four healthcare districts in Finland. Medical records were reviewed and data on incidence, diagnostic methods, phenotype [cranial vs large vessel (LV)-GCA] and clinical presentation were analysed.

Results: We identified 602 newly diagnosed GCA patients. The annual incidence was 9.0 cases/100 000 persons (95% CI 8.3, 9.7) ≥50 years of age and was significantly higher in the period 2016-2020 compared with the period 2010-2015 [11.3 (95% CI 10.1, 12.5) vs 7.0 (95% CI 6.2, 7.9), P < 0.001]. Imaging- or biopsy-confirmed diagnosis was recorded in 75% of GCA patients, while 25% had a clinical diagnosis. The proportion of imaging- or biopsy-confirmed diagnoses increased over time [64.7% (2010-2015) vs 82.2% (2016-2020)] while that of clinical diagnoses decreased. The use of imaging methods increased while the use of temporal artery biopsies decreased between the two time periods. LV-GCA was discovered more often in the period 2016-2020 when compared with 2010-2015 (34.0% vs 19.3% of patients).

Conclusion: The incidence of GCA increased during the study period, as well as the proportion of imaging- or biopsy-confirmed diagnoses, probably due to more frequent use of advanced imaging methods. Additionally, patients with LV-GCA were more commonly identified.