Patient Reported Outcomes Among Systemic Mastocytosis (SM) Patients in Routine Clinical Practice: Results from the TouchStone Survey

Introduction: SM is a rare, clonal mast cell neoplasm characterized by uncontrolled proliferation and activation of mast cells driven by the KIT D816V mutation, which leads to severe and unpredictable symptoms. This study evaluated disease and healthcare system burden of SM in a real-world treatment setting in the US.

Methods: In this cross-sectional study, SM patients recruited through the Mast Cell Connect Registry completed an online survey. The 100-item survey consists of symptom assessments using the ISM-SAF^© and widely used patient-reported outcomes (PRO) measures including the Short Form (SF)-12, Work Productivity and Activity Impairment (WPAI), and questions regarding SM-related medication and physician and emergency department (ED) visits during the past year. Patients ≥18 years with a self-reported diagnosis were included after providing informed consent. Established PRO measures were scored using established scoring algorithms. Data from the first 30 patients enrolled were analyzed using descriptive statistics.

Results: Thirty patients completed the survey: 87% female; mean age of 54 years; mean time since diagnosis of 8 years; mean time from symptom onset to diagnosis of 7 years; 80% reported indolent SM, 10% reported aggressive SM, 3% reported smoldering SM, and the remainder (7%) were uncertain of their type. Ninety percent reported ≥10 symptoms during the past year, the most bothersome being abdominal/stomach pain (17%), anaphylactic episodes (13%), diarrhea/loose stools (13%), and fatigue (10%). Most patients indicated they have moderate (43%) or severe (33%) disease.

Symptom Burden and Quality of Life (QoL) Impact

Mean ± SD mental and physical component summary scores from the SF-12 were 44 ± 1.8 and 43 ± 2.5, respectively, indicating below average health and mental well-being. The mean total symptom score (TSS) from the ISM-SAF was 50, with >28 indicating moderate-severe SM. Nearly all (27/30) patients reported that they strongly agreed (27%), agreed (40%) or somewhat agreed (23%) that SM had a negative impact on their QoL, and 50% (15/30) reported feeling a great deal (17%), quite a bit (10%), or somewhat (23%) depressed or discouraged due to their disease.

Use of Healthcare Services & Medications

Patients reported encounters with multiple physicians over the course of 1 year (Table). Most patients (90%) reported taking ≥2 over-the-counter (OTC) medications, and 40% of patients reported taking >3 prescription medications to manage SM. Twenty percent of survey respondents visited the ED due to anaphylaxis, with 50% of these patients requiring ED care for anaphylaxis on 3 different occasions. Fifty-seven percent (17/30) of patients reported managing at least 1 anaphylactic episode at home without visiting the ED, with 4 of these patients reporting ≥12 anaphylactic episodes within the past year.

Work Impairment

Limited activities due to pain attributed to SM were reported by 60% (18/30) of patients, and 56% (17/30) of patients indicated that pain interfered with their ability to work. 17% of respondents reported they were unable to work for pay, 46% of patients reported having to reduce work hours because of SM, and 20% of patients had filed for disability, all due to SM.

Conclusions: Despite close management by healthcare providers, and taking prescription and OTC medications, early findings from the TouchStone survey show that the majority of SM patients continue to report significant burden of disease, including inadequate symptom control, negative effects on QoL, reduced ability to work, frequent physician visits to manage SM and multiple, potentially costly, ED visits. These findings suggest high unmet medical need underscoring the value of more effective therapeutic interventions.