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Invasive aspergillosis: cost-effectiveness of the use of the galactomannan test in the decision to treat oncohaematological patients with antifungals: evaluation of the six-year experience at the Clinical Hospital of Unicamp (2012-2017)


Invasive fungal infection by Aspergillus spp (AI) is a complication seen mainly among patients with severe neutropenia due to chemotherapy for hematological malignancy or hematopoietic stem cell transplantation (HSCT). This infection presents great diagnostic difficulties, resulting in the delayed prescription of antifungals and high mortality. The diagnosis of AI is based on the combination of risk factors, symptoms, and signs, culture, histopathological examination and detection of antigenic components of the fungus, such as galactomannan (GM). GM is a component of the cell wall and its serum level has been used to establish rapid AI diagnosis. However, the impact of this test on the clinical decision to prescribe antifungals and whether it is cost-effective is still questioned. Objectives: To evaluate whether the GM test is a cost-effective decision-making strategy to introduce antifungal (preemptive treatment), comparing to empirical treatment or culture-confirmed treatment, from the perspective of the Hospital de Clínicas of UNICAMP; to determine the incidence of proven, probable and possible invasive aspergillosis according to the definition of EORTC / MSD in patients with hematological malignancies or who underwent bone marrow transplantation at Hospital de Clinicas, Unicamp, Campinas, in the period 2012-2017. Participants: All patients who underwent the GM test in the period 2012-2017 (450 patients) and attended by the Hematology discipline and in the HSCT service will be included. We will group the patients in relation to the empirical treatment (possible aspergillosis), preemptive (probable aspergillosis) and the diagnosis confirmed by culture (proved aspergillosis). We will analyze the patient's evolution too. Design: a cost-effectiveness economic analysis will be carried out from a retrospective cohort study. We will consider the direct costs related to diagnosis (GM, TC, and culture), antifungal treatment and hospital procedures, and hospitalization, health professionals involved in the strategies under investigation and overhead costs. To do so, we will use the bottom-up approach, through data collection in medical records and hospital cost management for overhead costs. Analysis: we will develop an analytical decision tree model to represent decision making on antifungal treatment. We will review the literature of economic evaluation studies of the GM test and consult specialists. We will calculate the incremental cost-effectiveness ratio by dividing incremental costs by incremental effectiveness, both in relation to the GM test compared to the culture. We will perform a sensitivity analysis of the model. The national and international methodological recommendations will be followed in economic evaluation. Expected results: contribute to improve the therapeutic decision protocols used in the institution; strengthen the line of research of evaluation of technologies in health, already developed by the Nucleus of Technology Assessment of UNICAMP. Collaborate for the training of students of scientific initiation and post-graduate students in health technology assessment. There are no national studies of economic analysis on the subject, and the results of this study can help to fill this knowledge gap (AU)