Estimating the Cost of Illness of Giant Cell Arteritis in the United States

INTRODUCTION Giant cell arteritis (GCA) is a chronic vasculitis affecting approximately 230,000 Americans. Limited data exist on the healthcare resource utilization and costs attributable to GCA. The objective of this study was to estimate the cost of illness in patients with GCA in the US. METHODS A cohort of patients with a new GCA diagnosis was identified from a large US claims database between 1 January 2008 and 31 December 2012. Newly diagnosed GCA patients were defined by two claims with GCA (ICD-9 446.5) as one of the listed diagnoses during the study period and no GCA diagnosis in the 12 months prior. Subjects without a GCA diagnosis were matched 5:1 to cases. One-year healthcare costs were compared among cases and controls, adjusting for covariates using generalized linear models. RESULTS A cohort of 1293 GCA patients and 6465 controls was identified. The mean age was 73 years, and 69% were females. Mean Charlson Comorbidity Index was 1.9 for GCA patients and 1.0 for controls. Mean 1-year cost for GCA patients was $34,065 [standard deviation (SD) $52,411], and mean 1-year cost for controls was $12,890 (SD $37,345). After multivariate adjustment, the difference in 1-year cost between GCA patients and controls was $16,431 (95% CI $13,821-$19,041). CONCLUSIONS Patients with GCA experience substantially higher healthcare costs in the first year following diagnosis compared to patients without GCA. These results add to the limited evidence available to inform researchers, clinicians, and policymakers on the cost burden of GCA in the US. FUNDING Genentech Inc.