Abstract
INTRODUCTION: Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are two related forms of systemic vasculitis. Patients with these conditions often experience relapses affecting various body systems. Here we describe rates of relapse and review healthcare costs resulting from relapse among patients with GPA/MPA. METHODS: Two groups of patients with GPA and MPA were selected from the MarketScan claims databases between 2011 and 2013 based on diagnosis codes. Patients were followed for 12 months to identify relapses based on an algorithm of diagnoses in medical and medication claims. Relapses were categorized into one of the following groups: renal relapse, pulmonary relapse, other relapse-associated condition relapse, GPA or MPA utilization relapse, and mixed relapse. RESULTS: The final sample of patients with GPA and MPA consisted of 2707 and 740 patients, respectively. In both groups, approximately one-quarter of patients experienced relapse during the 12-month follow-up period. The mean all-cause healthcare costs in the 4-month period after relapse were $38,313 (SD, $54,120) for patients with GPA and $35,947 (SD, $48,065) for patients with MPA. In both groups, renal relapses were the costliest. Costs during the 4 months immediately following relapses were substantially higher than what could be expected over a 4-month follow-up among patients who did not experience relapse based on 12-month all-cause costs (GPA, $32,005 [SD, $64,570]; MPA, $61,044 [SD, $125,093]). CONCLUSIONS: Relapses are common among patients with GPA and MPA, and treatment of relapses can be costly. More effective therapies are needed to prevent relapses. FUNDING: Genentech, Inc.