Clinical and Economic Burden of Antineutrophil Cytoplasmic Antibody-associated Vasculitis in the United States.

OBJECTIVE To describe the prevalence of major relapse and healthcare costs among patients with granulomatosis with polyangiitis (GPA); to find patients with microscopic polyangiitis (MPA) in administrative databases, because no MPA diagnosis code exists; and to describe the clinical and economic burden associated with MPA. METHODS Adults (≥ 18 yrs) with ≥ 2 diagnoses of GPA [International Classification of Diseases-9-Clinical Modification (ICD-9-CM 446.4)] during 2009-2013 were extracted from the Truven Health MarketScan Commercial and Medicare Supplemental databases. Evidence of major relapse (based on the Birmingham Vasculitis Activity Score) and healthcare costs were collected during 12-month and 24-month followup periods. Adults with ≥ 2 diagnoses of unspecified arteritis (ICD-9-CM 447.6) were found as potential patients with MPA and additional criteria based on clinical input were applied to refine the sample. Major relapse-associated conditions and healthcare costs in the 6 months pre- and post-diagnosis were measured. Costs were inflated to 2013 US$. RESULTS A total of 2784 patients with GPA were found and 18.7% experienced a major relapse in the 12-month followup period. The patients with a major relapse incurred higher average all-cause (12-month: $88,065 vs $30,682; p < 0.0001) and GPA-related costs (12-month: $61,636 vs $15,748; p < 0.0001) than patients without a relapse. Trends were consistent over the 24-month followup period. There were 612 incident patients with MPA. Following MPA diagnosis, healthcare costs nearly doubled ($30,166 vs $56,642; p < 0.0001). CONCLUSION In a real-world setting, patients with GPA who experience major relapse have higher economic burden, compared to patients without a relapse. MPA diagnosis was associated with nearly a 2-fold increase in healthcare costs.