Frequency, diagnosis, and pharmacological treatment of giant cell arteritis in Germany: database analysis of medical insurance data

Background: For giant cell arteritis (GCA), a north-south gradient in incidence and prevalence has been described, peaking in Scandinavia. Objective: This analysis aimed to obtain up-to-date, representative data on the prevalence and incidence of GCA in Germany, updating the old, regional information on low incidence and prevalence rates. Design: Cross-sectional analysis using a large German health insurance database. Methods: This study is based on a cross-sectional analysis of claims data from the InGef (Institute for Health Research Berlin GmbH) research database, which includes a representative sample of 4.8 million insured individuals. Individuals aged ⩾50 years with continuous insurance coverage for a 3-year baseline period and the subsequent 2 years for longitudinal analysis were included. Estimates were standardised and projected to the German population. Results: Each year from 2018 to 2021, 1.7 million insured individuals met the inclusion and exclusion criteria. Extrapolated to the German population ⩾50 years in 2021, the incidence was 24/100,000, and the prevalence was 146/100,000. Diagnosis was made predominantly in outpatient settings by general practitioners (GP, 31.9%) and internists (19.5%), followed by rheumatologists (13.1%) and ophthalmologists (5.7%). Within 2 years, 16.3% of incident patients were referred to rheumatologists for treatment after diagnosis. Treatment was most commonly initiated by GPs (45.8%), followed by rheumatologists (36.1%), and included glucocorticoids (88.2%), methotrexate (26.7%), and tocilizumab (14.1%). Most common comorbidities of prevalent patients comprised arterial hypertension (77.2%), dyslipidaemia (55.0%), diabetes mellitus (28.8%), osteoporosis (34.6%), and cataract (31.2%). Conclusion: Contrary to previous reports, Germany has higher incidence and prevalence rates of GCA than previously assumed. Only approximately one-third of the incident patients were initially treated by rheumatologists. Comorbidities such as diabetes or cardiovascular diseases were common.