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The relevance of the spillover effects in the evaluation of Alzheimer's disease interventions
Published on 5 December 2024


Since dementia carries significant social and economic implications, the evaluation of health and social care systems is crucial. This approach can offer the most reliable evidence for policy and service development. In this sense, one of the main functions of economic analysis is to generate information useful for informing decision-makers about the health and welfare costs and benefits of choices about health interventions [1], as broad public health programmes, new treatments, the use of medical devices, or changes in the organisation of health care services, without exhausting the list.


An important element to consider is the perspective from which the analysis is performed. This perspective is usually limited to the health system (on the cost side) and to the patients affected by a disease (in the case of health and well-being outcomes). However, in the case of diseases such as dementia, such a perspective is clearly insufficient.


The term ‘spillover effect’ refers to situations in which a situation experienced, or action taken by one person can affect not only that person but also the well-being of others [2]. Although the concept can be applied to a variety of situations, e.g. vaccination programmes, the context in which spillover effects have been most studied has been in the family and affective environment of people receiving non-professional (informal) care [3].


In the specific case of Alzheimer's disease, the scientific literature shows that the resource most used in the care of patients, and which has the greatest weight in the total cost of the disease, is informal care [4][5][6][7][8][9]. A recent Spanish study estimated that the replacement of informal care by professional carers for people with Alzheimer's disease would require a budget similar to that of the entire System for Autonomy and Dependency Care [10].


Likewise, from the perspective of the health and well-being of carers, although caregiving can have positive aspects from the point of view of personal fulfilment, an excessive burden, derived from long hours of care, with arduous tasks, and prolonged for months or years with hardly any rest, translates into the appearance and exacerbation of problems in the work, family and social spheres, as well as the deterioration of the carer's own health [11][12][13].


Both elements, the resource of time spent on care and the impact on the well-being of carers, mean that the perspective to be applied in interventions affecting people with Alzheimer's disease should be the social perspective. The sole consideration of the health perspective could make interventions that save resources for the health system good and convenient, despite resulting in a greater burden and impact on the well-being of caregivers [14][15]. For this reason, interventions such as CAREPATH must consider both the effect on costs and health outcomes in patients and their care environment, in order for the analysis to be consistent with the goals of effectiveness, safety, efficiency and equity.



References
  1. O’Rourke B, Oortwijn W, Schuller T (2020). The new definition of health technology assessment: A milestone in international collaboration. Int J Technol Assess Health Care;1–4.
  2. Basu A, Meltzer D. Implications of spillover effects within the family for medical cost-effectiveness analysis. J Health Econ. 2005;24(4):751–73.
  3. Grosse, S.D., Pike, J., Soelaeman, R. et al. Quantifying Family Spillover Effects in Economic Evaluations: Measurement and Valuation of Informal Care Time. PharmacoEconomics 37, 461–473 (2019).
  4. Kosaner Kließ M, Martins R, Connolly MP. Major Cost Drivers in Assessing the Economic Burden of Alzheimer's Disease: A Structured, Rapid Review. J Prev Alzheimers Dis. 2021;8(3):362-370.
  5. Wimo A, Seeher K, Cataldi R, Cyhlarova E, Dielemann JL, Frisell O, Guerchet M, Jönsson L, Malaha AK, Nichols E, Pedroza P, Prince M, Knapp M, Dua T. The worldwide costs of dementia in 2019. Alzheimers Dement. 2023 Jul;19(7):2865-2873.
  6. Onetiu, V., Aurelian, S. M., Capisizu, A., Cristescu, F., Zus, I. C., & Kissimova-Skarbek, E. (2016). Cost of dementia in Romania: a cross-sectional Cost-of-Illness study undertaken in Bucharest. Zeszyty Naukowe Ochrony Zdrowia, Zdrowie Publiczne i Zarządzanie, 14(3).
  7. Martins R, Kotsopoulos N, Michalowsky B, Pemberton-Ross P, Urbich M, Connolly MP. Evaluation of the Fiscal Costs and Consequences of Alzheimer's Disease in Germany: Microsimulation of Patients' and Caregivers' Pathways. J Prev Alzheimers Dis. 2022;9(4):758-768.
  8. Lenox-Smith A, Reed C, Lebrec J, Belger M, Jones RW. Potential cost savings to be made by slowing cognitive decline in mild Alzheimer's disease dementia using a model derived from the UK GERAS observational study. BMC Geriatr. 2018 Feb 23;18(1):57.
  9. Gómez Maldonado L, de Mora-Figueroa R, López-Angarita A, Maravilla-Herrera P, Merino M. Cost of Patients with Alzheimer's Disease in Spain According to Disease Severity. Pharmacoecon Open. 2024 Jan;8(1):103-114.
  10. Vilaplana Prieto C, Oliva-Moreno J. Time value of informal care of people with alzheimer's disease in Spain: a population-based analysis. Eur J Health Econ. 2024.
  11. Peña-Longobardo LM, Oliva-Moreno J. Caregiver burden in Alzheimer's disease patients in Spain. J Alzheimers Dis. 2015;43(4):1293-302.
  12. Frederiksen KS, Lanctôt KL, Weidner W, Hahn-Pedersen JH, Mattke S. A Literature Review on the Burden of Alzheimer's Disease on Care Partners. J Alzheimers Dis. 2023;96(3):947-966.
  13. Bauer, J., Sousa-Poza, A.: Impacts of informal caregiving on caregiver employment, health, and family. J. Popul. Ageing. 8, 113–145 (2015).
  14. Mott DJ, Schirrmacher H, Al-Janabi H, Guest S, Pennington B, Scheuer N, Shah KK, Skedgel C. Modelling Spillover Effects on Informal Carers: The Carer QALY Trap. Pharmacoeconomics. 2023 Dec;41(12):1557-1561.
  15. Lin PJ, D'Cruz B, Leech AA, Neumann PJ, Sanon Aigbogun M, Oberdhan D, Lavelle TA. Family and Caregiver Spillover Effects in Cost-Utility Analyses of Alzheimer's Disease Interventions. Pharmacoeconomics. 2019 Apr;37(4):597-608.