Background/Purpose: Eosinophilic granulomatosis with polyangiitis (EGPA), formerly Churg-Strauss Syndrome, is a rare, complex multisystem disorder belonging to a group of autoimmune inflammatory diseases characterized by vascular inflammation, multisystem organ damage that manifests as chronic rhinosinusitis, asthma, and peripheral blood eosinophilia. In part due to the rare nature of EGPA and lack of specific ICD-9 codes, there is an absence of burden of illness data. Introduction of an EGPA-specific ICD-10 diagnosis code (M30.1) should facilitate such analyses. In this regard, this study aims to describe EGPA burden of illness in the United States (US).

Methods: This is a retrospective analysis of two US administrative claims databases. The index date was defined as the first medical claim with an ICD-10 diagnosis for EGPA. The study period spanned from ICD-10 introduction (01 October 2015) through the most recent data availability (Database #1 [DB#1]: 31 December 2016; Database #2 [DB#2]: 31 March 2017). Patients were ≥18 years of age, had ≥1 medical claim with an ICD-10 diagnosis code for EGPA, and had 6 months of continuous health plan enrollment post-index. Six-month post-index clinical and economic characteristics are reported as counts (percentages) and means (standard deviations [SD]).

Results: Approximately 0.0017% of the population had an EGPA diagnosis (DB#1: 567/33,293,530; DB#2: 413/23,796,590) (Table 1). Mean (SD) age was 54.9 (14.1) in DB#1 and 59.7 (16.0) in DB#2; and overall, approximately 60% of patients were female. Mean (SD) Quan-Charlson Comorbidity Index score was 1.3 (1.3) in DB#1 and 1.6 (1.7) in DB#2 (AHRQ top 5 comorbidities were similar across databases). Post-index concomitant medications included (DB#1/DB#2): asthma-related medications (non-biologic: 65.5%/55.9%; biologic: 5.2%/3.4%), immunosuppressive medications (84.8%/75.5%), and oral corticosteroids (OCS; 73.5%/59.0%). Among patients receiving OCS, mean (SD) prednisone-equivalent daily dose was 53.9 mg/day (248.1) in DB#1 and 18.8 mg/day (13.8) in DB#2 (median dose was 15 mg/day in both databases). Post-index, all-cause healthcare resource utilization was similar across databases with 16.9% of patients in DB#1 incurring an inpatient admission (mean [SD] admissions: 1.5 [1.1) and 20.3% of patients in DB#2 (mean [SD] admissions: 1.3 [0.7]). Mean (SD) all-cause total costs incurred in the post-index period were $32,388 (113,895) in DB#1 and $20,865 (33,665) in DB#2.

Conclusion: This study descriptively characterizes the substantial clinical and economic burden associated with EGPA. While EGPA is a rare disease, the introduction of an EGPA-specific ICD-10 diagnosis code should allow researchers to better quantify the burden of illness.

This study was funded by GlaxoSmithKline (Study #: HO-17-18985)

Abstract previously presented at ATS 2018, A4951 (P162)