Budget Impact Analysis of Disease-Modifying Therapies for Alzheimer's Disease in Ireland: A Model-Based Analysis

BackgroundDisease-modifying therapies (DMTs) for Alzheimers disease, including lecanemab and donanemab, have received regulatory approval in multiple jurisdictions. These therapies require complex diagnostic workup and safety monitoring, raising significant budget impact concerns for healthcare payers. No budget impact analysis specific to Ireland or comparable small European healthcare systems has been published. ObjectiveTo estimate the 5-year budget impact of introducing DMTs for early-stage Alzheimers disease in Ireland from the Health Service Executive (HSE) payer perspective. MethodsA budget impact model was developed following International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines. The model incorporated Irish epidemiological data, published drug prices, and healthcare resource utilisation estimates. Three treatment uptake scenarios (conservative, base case, optimistic) were modelled over a 5-year time horizon. Sensitivity analyses examined parameter uncertainty. ResultsFrom an estimated eligible population of 11,568 individuals with early-stage Alzheimers disease, annual budget impact in Year 5 ranged from {euro}12.8 million (conservative: 3% uptake) to {euro}89.6 million (optimistic: 20% uptake), with a base case estimate of {euro}35.8 million (8% uptake). Cumulative 5-year budget impact ranged from {euro}32.0 million to {euro}224.0 million. Drug acquisition costs represented 61% of total expenditure, with diagnostic and monitoring costs comprising 24% and 15%, respectively. Sensitivity analysis identified drug price, eligible population size, and treatment uptake as the most influential parameters. ConclusionsIntroduction of DMTs for Alzheimers disease will have a substantial but manageable budget impact on the Irish healthcare system, contingent on treatment uptake rates constrained by diagnostic capacity. Strategic investment in diagnostic infrastructure, phased implementation, and negotiated drug pricing could mitigate budgetary pressures while enabling patient access to these novel therapies. Key Points for Decision MakersO_LIThis is the first budget impact analysis of disease-modifying therapies (DMTs) for Alzheimers disease specific to Ireland, a small European healthcare system with constrained diagnostic capacity. C_LIO_LIAnnual budget impact ranges from {euro}12.8 million (conservative scenario) to {euro}89.6 million (optimistic scenario) in Year 5, representing 0.05% to 0.33% of the total Health Service Executive budget. C_LIO_LIDrug acquisition costs account for 58-65% of total expenditure, with diagnostic workup and safety monitoring comprising substantial ancillary costs. C_LIO_LIPhased implementation aligned with diagnostic infrastructure expansion could enable budget-neutral introduction through efficiency gains in dementia care pathways. C_LI