Comparing the cost-effectiveness of two screening strategies for latent tuberculosis infection in Portugal
Sofia Sousa,
Diogo Rocha,
Joelma C. Silva,
Ana Isabel Ribeiro,
Guilherme Gonçalves,
Álvaro Almeida,
Ana Maria Correia,
Raquel Duarte,
Carlos Carvalho
Affiliations
Sofia Sousa
Public Health Unit - South Sousa Valley, Northern Regional Health Administration, Paredes, Portugal; Multidisciplinary Unit for Biomedical Research (UMIB), Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal; Corresponding author.
Diogo Rocha
Faculty of Medicine, University of Porto, Porto, Portugal
Joelma C. Silva
Pulmonology Department of Centro Hospitalar de Trás-os-Montes e Alto Douro, Vila Real, Portugal
Ana Isabel Ribeiro
Epidemiology Research Unit (EpiUnit) - Institute of Public Health, University of Porto, Porto, Portugal; Departamento de Ciências de Saúde Pública, Ciências Forenses e Educação Médica, Faculty of Medicine, University of Porto, Porto, Portugal
Guilherme Gonçalves
Multidisciplinary Unit for Biomedical Research (UMIB), Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
Álvaro Almeida
CEF.UP – Center for Economics and Finance at the University of Porto and Faculdade de Economia, Universidade do Porto
Ana Maria Correia
Northern Regional Health Administration, Department of Public Health, Porto, Portugal
Raquel Duarte
Epidemiology Research Unit (EpiUnit) - Institute of Public Health, University of Porto, Porto, Portugal; Departamento de Ciências de Saúde Pública, Ciências Forenses e Educação Médica, Faculty of Medicine, University of Porto, Porto, Portugal; Serviço de Pneumologia, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal; National Tuberculosis Program, Directorate-General of Health, Lisbon, Portugal
Carlos Carvalho
Public Health Unit - South Sousa Valley, Northern Regional Health Administration, Paredes, Portugal; Department of Public Health, Northern Regional Health Administration, Porto, Portugal; Multidisciplinary Unit for Biomedical Research (UMIB), Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
Introduction and objectives: Screening for latent tuberculosis infection (LTBI) in close contacts of infectious TB cases might include Tuberculin Skin Test (TST) and Interferon-Gamma Release Assays (IGRA), in combination or as single-tests. In Portugal, the screening strategy changed from TST followed by IGRA to IGRA-only testing in 2016. Our objective was to compare the cost-effectiveness of two-step TST/IGRA with the current IGRA-only screening strategy in immunocompetent individuals exposed to individuals with respiratory TB. Materials and Methods: We reviewed clinical records of individuals exposed to infectious TB cases diagnosed in 2015 and 2016, in two TB outpatient centers in the district of Porto. We estimated medical, non-medical and indirect costs for each screening strategy, taking into account costs of tests and health care personnel, travel distance from place of residence to screening site and employment status. We calculated the incremental cost-effectiveness ratio (ICER) as the cost difference between the two screening strategies with the difference number of LTBI diagnosis as a measure of cost-effectiveness, assuming that treating LTBI is a cost-effective intervention. We also calculated adjusted odds-ratios to test the association between diagnosis of LTBI and screening strategy and estimated the total cost for averting a potential TB case. Results: We compared 499 contacts TST/IGRA screened with 547 IGRA-only. IGRA-only strategy yielded a higher screening effectiveness for diagnosing latent tuberculosis infection (aOR 2.12, 95%CI: 1.53 - 2.94). ICER was €106 per LTBI diagnosis, representing increased effectiveness with a slightly increased cost of IGRA-only screening strategy. Conclusions: Our data suggests that in Portugal LTBI screening with IGRA-only is more cost-effective than the two-step TST/IGRA testing strategy, preventing a higher number of cases of TB cases.
