Retrospective study characterising clinical manifestations and treatment patterns of hypereosinophilic syndrome in Europe

Introduction: Hypereosinophilic syndrome (HES) is a rare group of blood disorders characterised by prolonged eosinophilia leading to organ damage. Limited information is available on the clinical manifestations of HES, and treatment patterns for patients with HES in Europe. Aims: To describe the clinical characteristics and treatment patterns for patients with HES in Europe. Methods: This retrospective chart review study included patients ≥6 years old with a confirmed HES diagnosis and ≥1 year of follow-up data from index (first physician encounter: Jan 2015–Dec 2019). Chart review was conducted using a panel of 121 physicians from 5 European countries. Clinical characteristics and treatment patterns were assessed. Results: Of the 280 patients included, 65% were male, patients received multiple diagnostic tests (mean [SD] = 9.2 [4.1]) and 55% had idiopathic HES. Overall, mean (SD) age at HES diagnosis was 42 (16.2) years and the most common comorbidities were asthma (45%) and anxiety or depression (36%). Post diagnosis, 39% of patients received ≥3 distinct HES therapies, 89% used OCS and 64% used immunosuppressive/cytotoxic agents. During follow-up, 29% of patients reported ≥5 distinct clinical manifestations, the lungs (49%) and skin (48%) were the organs most frequently affected and 50% of patients had fatigue; 23% of patients experienced a flare. Conclusions: There is a substantial burden of comorbidities and heterogeneity in manifestations among patients with HES and many tests are required to reach a diagnosis. Despite receiving multiple therapies some patients experienced a flare, highlighting suboptimal management and unmet needs. Funding: GSK (214657)