Real-World Insights on the Burden of Hypereosinophilic Syndrome (HES)

HES is a group of rare hematological disorders marked by a persistently elevated eosinophil count along with tissue and organ damage. Real-world data describing characteristics and treatment patterns of HES patients managed by specialists in non-academic centers is limited. We performed a retrospective chart review study using Electronic Medical Record (EMR) data from Allergy Partners (AP) network (2007–2021). HES patients were identified based on a clinical diagnosis of HES and an absolute eosinophil count (AEC) of >=1,500/microliter. Patients were followed longitudinally from index date (first AP visit) until end of data availability. Of the 99 HES patients identified, 52 patients met all eligibility criteria (53.8% female, 57.7% white, median age of diagnosis: 40.5 years, median age at index: 42.5 years). Half of the patients received their first HES diagnosis outside the AP network and primary care physicians were the most common referring physician (65.4%), followed by hematologist (11.5%). Rhinitis (71.2%) and asthma (44.2%) were common comorbidities. The median (interquartile range [IQR]) peak AEC was 2200.0/microliter (1700.0, 3300.5). Half of the patients reported >=15 distinct symptoms during entire study period, with >80% of the patients reporting fatigue, headache, dizziness, rash, itch, vomiting, diarrhea, abdominal pain, chest pain, palpitations, respiratory symptoms, and weight loss. 50.0% of the patients received oral corticosteroids (OCS) and 44.2% received chronic OCS dose (>=5 mg/day prednisone equivalent). Our findings highlight a substantial burden of illness and considerable unmet need in HES patients, emphasizing the need to improve diagnosis and management in this patient population.