People with indolent systemic mastocytosis (ISM) — the most common form of systemic mastocytosis (SM) — had more symptoms and higher rates of bone disease than similar individuals without the condition in a real-world study published in the Journal of Allergy and Clinical Immunology: Global.
Researchers at the Mayo Clinic used natural language processing to analyze the health records of approximately 7.5 million patients between 2005 and 2022. The study compared 203 individuals diagnosed with ISM to a control group of 2,030 people to better understand the long-term impact and natural history of this rare disease.
The results revealed that the impact of ISM is not static. At the start of the study, patients with ISM had a mean symptom burden of 7.4. This number represents the average count of the different types of symptoms — such as skin rashes, digestive issues or joint pain — reported by each patient. By the end of the follow-up period (which averaged 4.4 years), this number increased significantly, to 10.4. This indicates that as time passes, patients do not just feel existing symptoms more intensely; they often develop new types of complications across different organ systems.
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Despite the increasing severity of symptoms, researchers found no significant difference in mortality rates between patients with ISM and matched controls. However, they found the condition carries a high risk of acute events. The risk of life-threatening anaphylaxis was eight times higher in those with ISM, affecting 26.6% of the group compared with just 3.3% of the control cohort.
One of the most persistent findings was the high rate of bone involvement. Osteopenia or osteoporosis affected 68% of patients with ISM, while these conditions affected only 28% of the control group. The condition also took a toll on mental health; more than half of patients (52.2%) reported anxiety and 45.3% experienced depression, rates that were notably higher than those seen in the control group.
Healthcare use was also significantly higher among patients with ISM, including more outpatient, inpatient and emergency department visits. Additionally, medication use was greater, often focused on symptom control rather than modifying the disease itself.
“These findings support the consideration of disease-modifying therapies in ISM management,” the study’s authors noted. They emphasized that the high symptom burden and frequent use of healthcare services reinforce the need for earlier diagnosis and multidisciplinary management strategies.
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