Uso de modelos de análise de decisão nos programas de vacinação contra a varicela / Use of decision analysis models in the programs of vaccination against varicella

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

BACKGROUND: The choice between different decision analysis models introduces variability in the results of economic evaluations. Static models do not take into account the indirect effects of vaccination, thus compromising the overall assessment of vaccination benefits. This work developed two models one dynamic and another static to conduct cost-effectiveness analyses (CEA) of varicella vaccine, comparing the results of the two. METHODS: Comprehensive economic evaluation CEA using modeling. The analysis compared two strategies: 1) introduction of routine vaccination for children under 12 months, versus 2) current situation (vaccination after outbreaks in nurseries and vaccination of immunocompromised). The time horizon of the analysis was 30 years. RESULTS: The dynamic model estimated that in the absence of the vaccination program, 2 915 294 cases of varicella occurred every year in Brazil, resulting in 879,095 outpatient cases, 4,507 hospitalizations, 119 deaths and 4 sequela cases. The total annual cost of varicella was estimated at R$ 27,378,957 for the society and at R$ 14,412,610 for the health care system. From the perspective of society, the incremental cost-effectiveness ratio (ICER) was R$ 14,749 per life-year saved, while from the perspective of the health care system, it amounted to R$ 16,582. The model estimated that, in the absence of a vaccination program, there would be 1,656,547 cases of varicella every year in Brazil, resulting in 629,488 outpatient cases, 5,120 hospitalizations, 82 deaths and 1 case of sequela. The total annual cost of varicella was estimated at R$ 17,311,412 for the society, and at R$ 9,570,551 for the health care system. The ICER was R$ 35,254 and R$ 36,599 from the perspective of society and the health care system, respectively. When applying the World Health Organization (WHO)s cost-effectiveness threshold to the dynamic model results, vaccination was considered a cost-effective strategy; this was nevertheless not the case with the static model. In the sensitivity analysis for the incidence rate employed in the static model, the ICER was R$ 19,905 per life-year saved from the perspective of society, and R$ 21,176 from the perspective of the health care system, with vaccination deemed cost-effective. CONCLUSION: Estimating the cost-effectiveness of vaccination programs requires the use of an appropriate model. Establishing an appropriate course of action will depend on the context of proposal evaluation, understanding of disease epidemiology, availability of data, and the existence of a qualified team to build these models and interpret their results.

ASSUNTO(S)

immunity herd cost-effectiveness evaluation avaliação de custo-efetividade custos e análises de custo varicela models economic imunidade coletiva modelos epidemiológicos chickenpox modelos econômicos costs and cost analysis epidemiologic models

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