Risk of Vertebral Fracture in Patients with ESKD Secondary to Vasculitis

Background Glucocorticoids are central to vasculitis treatment, but increase vertebral fracture risk. This study assessed whether vasculitis as the cause of ESKD is associated with incident vertebral fracture, controlling for corticosteroid use. Methods A retrospective cohort study was conducted from 2006 to 2019 on adults in the United States Renal Data System initiating dialysis between 2006 and 2017, surviving $1 year, with continuous Medicare Part D coverage during the first year of dialysis. Primary exposure was vasculitis as the cause of ESKD determined from Centers for Medicare & Medicaid Services form 2728, completed by a physician at dialysis initiation. A granulomatosis with polyangiitis (GPA) subgroup had $1 International Classification of Diseases, Ninth Revision (ICD-9)/International Classification of Diseases, Tenth Revision (ICD-10) code for GPA in the first dialysis year. One inpatient or two outpatient ICD-9/10 codes within 90 days defined incident vertebral fracture. Clinical covariates were ascertained from Centers for Medicare & Medicaid Services form 2728 and ICD-9/10 codes and pharmacy claims over the first dialysis year. Multivariate logistic regression examined the association of ESKD secondary to vasculitis with incident vertebral fracture and in GPA in a secondary analysis. Results Among 633,543 patients with ESKD, vertebral fracture occurred in 6.18% with and 3.23% without ESKD from vasculitis. After multivariate adjustment including corticosteroid daily dose in the first dialysis year, ESKD secondary to vasculitis was associated with vertebral fracture (relative risk, 1.33; 95% confidence interval, 1.17 to 1.52) and similarly in those with GPA (relative risk, 1.47; 95% confidence interval, 1.23 to 1.75). Conclusions ESKD from vasculitis, and from GPA specifically, increases vertebral fracture risk among patients with ESKD after accounting for first dialysis year corticosteroid dose.