I. How to Use
When to Use
This prognostic tool is relevant for patients with both non-advanced and advanced systemic mastocytosis.
Pearls / Pitfalls
The validation study excluded patients with mast cell sarcoma and children (< 17 years) with cutaneous mastocytosis. The score did not evaluate nonroutine laboratory values such as ß2-microglobulin given the retrospective nature.
Why Use
This simple tool has strong prognostic implications based on age, laboratory values, and skin involvement. It can be incorporated into clinic discussions to potentially assist in treatment decisions.
II. Next Steps
Advice
This tool should not be the sole basis for care, and clinicians should use judgment and a full clinical evaluation. The score could be used to contextualize WHO classification and aid in treatment discussions.
Management
The validation study did not lead to any specific management recommendations but instead to consider the risk stratification when balancing tradeoffs between curative potential and side effects of treatment options.
Critical Actions
Management of systemic mastocytosis should be guided by clinician judgment, regardless of the IPSM score.
III. Evidence
Evidence Appraisal
The validation study that created the IPSM confirmed the prognostic value of the WHO classification of mastocytosis into distinct variants. A total of 1639 patients were analyzed to identify variables predictive of survival that were included in the score and 462 patients to validate the IPSM. Prognostic variables were included if the hazard ratio was 1.50 or higher (+1) or 0.50 or lower (-1). IPSM scores were predictive of overall survival, progression-free survival, and event-free survival (all p<0.0001).
A follow-up study further stratified the advanced systemic mastocytosis (AdvSM) IPSM risk score by using serum tryptase, alkaline phosphatase, ß2 microglobulin, lactate dehydrogenase, and albumin.
Formula
Non-Advanced Systemic Mastocytosis
Age: 60+ yo (+1) vs < 60 yo (0)
Alkaline Phosphatase: 100+ IU/L (+1) vs < 100 IU/L (0)
Risk Level = low (0), intermediate-1 (1), and intermediate-2 (2)
Advanced Systemic Mastocytosis (AdvSM)
Age: 60+ yo (+1) vs < 60 yo (0)
Tryptase: 125+ ng/mL (+1) vs < 125 (0)
Leukocyte: 16+ x 109/L (+1) vs < 16 x 109/L (0)
Hemoglobin: < 11 g/dL (+1) vs > 11 g/dL (0)
Platelet: < 100 x 109/L (+1) vs > 100 x 109/L (0)
Skin Involvement: yes (-1) vs no (0)
Risk Level = AdvSM-1 (-1 to 0), AdvSM-2 (1), AdvSM-3 (2-3), AdvSM-4 (4-5)
Facts & Figures
10-year overall survival was 98.1% for low-risk non-advanced systemic mastocytosis, 87.1% for intermediate-1 risk, and 52.1% for intermediate-2 risk level, and 22.0% for advanced systemic mastocytosis (AdvSM). 10-year progression-free survival was 96.3%, 86.7%, 76.3%, and 61.1%, respectively. AdvSM risk groupings were prognostic for overall survival, progression-free survival, and event-free survival (p<0.0001).
Literature
Original/Primary & Validation
Sperr WR et al. International prognostic scoring system for mastocytosis (IPSM): a retrospective cohort study. Lancet Haematol. 2019;6(12):e638-e649. PMID 31676322.
Other References (including meta-analyses, CPGs, and impact analyses)
Lübke J et al. Serum chemistry profiling and prognostication in systemic mastocytosis: a registry-based study of the ECNM and GREM. Blood Adv. 2024;8(11):2890-2900. PMID 38593217.