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HEOR / Market Access

Monte Carlo
Budget Impact Model

A probabilistic budget impact model simulating the financial consequences of bezuclastinib entering the systemic mastocytosis market against Ayvakit (avapritinib). This proof of concept demonstrates AMCP-format payer analytics with 10,000 Monte Carlo iterations, tornado sensitivity analysis, and three-scenario comparison — built entirely in-browser with no backend dependencies.

Monte Carlo SimulationTornado SensitivityBudget Impact AnalysisHEORScenario ModelingProbabilistic DistributionsPMPM ProjectionsInteractive Parameters

Methodology: Monte Carlo simulation (10,000 iterations) with configurable epidemiological, pricing, and market share parameters. Tornado sensitivity analysis and scenario comparison across payer archetypes.

Running 10,000 Monte Carlo iterations...

Technical Architecture

Monte Carlo Engine

10,000 iterations with seeded PRNG (Mulberry32) for full reproducibility. Each iteration independently samples 16 parameters from their respective distributions, computes the population funnel, and calculates two-world cost differentials.

Distribution Sampling

Normal (Box-Muller), Beta (Marsaglia-Tsang gamma method), and Triangular (inverse CDF) distributions. Beta distributions model bounded proportions while Triangular captures expert-elicited ranges with asymmetric uncertainty.

Sensitivity Analysis

One-way tornado analysis varies each parameter ±20% from base case while holding all others constant. Ranks parameters by absolute swing in net budget impact, identifying the key cost drivers for payer negotiation strategy.

References

  • Sullivan SD, et al. Budget impact analysis — principles of good practice: report of the ISPOR 2012 Budget Impact Analysis Good Practice II Task Force. Value Health. 2014;17(1):5-14.
  • AMCP Format for Formulary Submissions, Version 4.1. Academy of Managed Care Pharmacy. 2020.
  • Gotlib J, et al. Avapritinib for advanced systemic mastocytosis (PATHFINDER). N Engl J Med. 2021;384(14):1343-1353.
  • DeAngelo DJ, et al. Bezuclastinib for advanced systemic mastocytosis (APEX): Phase 2 results. Blood. 2023;142(Suppl 1):Abstract 620.
  • Jennings S, et al. The Mastocytosis Society survey on mast cell disorders: prevalence and clinical phenotype. J Allergy Clin Immunol Pract. 2014;2(1):70-76.
  • Briggs AH, et al. Model parameter estimation and uncertainty analysis: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force. Med Decis Making. 2012;32(5):722-732.

Daniel Tran, PharmD

UC San Diego — Skaggs School of Pharmacy

Source code MIT. Content © 2026 Daniel Tran (CC BY-NC-SA 4.0).