Poster: MDS-094 Characteristics and Management of Medicare Beneficiaries With Advanced Systemic Mastocytosis

Advanced systemic mastocytosis (AdvSM) (subtypes: aggressive SM, SM with associated hematological neoplasm, mast cell leukemia) is a rare clonal mast cell neoplasm driven by the KIT D816V mutation. Uncontrolled proliferation, accumulation, and activation of mast cells result in severe symptoms in various organ systems, making SM difficult to diagnose. Clinical guidelines recommend comprehensive testing and specialist care management.To describe AdvSM patient characteristics and use of healthcare services before AdvSM diagnosis in the US Medicare population. Design, Patients, and Outcomes: Medical and pharmacy encounter data for the full US Medicare Fee-for-Service population and a claims-based algorithm were used to identify patients with newly diagnosed AdvSM (≥2 medical claims for AdvSM-related diagnoses [ICD-10 C94.3, D47.02, C96.21] or other qualifying mast cell neoplasm codes by subtype) between January 1, 2017, and December 31, 2019. Continuous enrollment in Medicare for 12 months pre- and post-AdvSM diagnosis was required. Demographics, comorbidity profile, and pre-diagnosis healthcare resource utilization were analyzed.A total of 468 patients with AdvSM met the criteria for analysis; most received their index diagnosis from a hematologist/oncologist. The mean (SD) age was 66.8 (13.6) years, 62% were female, 91% were Caucasian, 30% were dually eligible for Medicare/Medicaid (indicating lower socioeconomic status), and 31% qualified for Medicare due to non-age-related factors (e.g., disability). The mean (SD) Charlson Comorbidity Index score was 4.1 (3.2). Comorbidities included hypertension, 65%; malignancies (including mast cell neoplasms, solid tumors, and hematologic cancers), 62%; pulmonary disease, 43%; depression, 32%; anxiety, 29%; diabetes, 29%; asthma, 26%; and osteoporosis, 22%. In the year before AdvSM diagnosis, patients had a mean (SD) of 4.6 (5.1) primary care visits and 19.6 (18.5) physician specialist visits; 22% underwent bone marrow biopsy, 5% KIT D816V mutation testing, and 48% serum tryptase testing. The majority of patients were prescribed anti-mediator drug therapy (67% corticosteroids, 41% proton pump inhibitors, 29% antileukotrienes, 28% montelukast); 20% were prescribed epinephrine injectors for treatment or prevention of anaphylaxis.Medicare patients newly diagnosed with AdvSM had evidence of high rates of comorbid disease, specialist visits, and symptom management regimens prior to confirmed diagnosis. Care should be closely coordinated by specialists to optimize timely AdvSM diagnosis and management.