Cost-effectiveness of serological tests for human visceral leishmaniasis in the Brazilian scenario

Human visceral leishmaniasis (VL) is a severe and potentially fatal parasitic disease if not correctly diagnosed and treated. Brazil is one of the three countries most endemic for VL and, like most countries affected by this disease, has a large budget constraint for the incorporation of new health technologies. Although different diagnostic tests for VL are currently available in the country, economic studies evaluating diagnostic kits are scarce. The objective of this study was to conduct a cost-effectiveness analysis of the nine available diagnostic tests for human VL in HIV-infected and uninfected patients in Brazil. The perspective of analysis was the Brazilian public health system, and the outcome of interest was "cases diagnosed correctly". The costs of the tests were estimated using the microcosting technique, and comparisons were performed with decision trees. Sensitivity analyses were explored applying variations in cost and effectiveness values. For VL diagnosis among HIV-uninfected patients, using blood samples for the rapid tests (RDTs), the noncommercial direct agglutination test (DAT-LPC) and IT-LEISH were cost-effective tests compared with the baseline OnSite test, but they presented different incremental cost-effectiveness ratios (ICER) of US$7.04 and US$ 205.40, respectively. Among HIV-infected patients, DAT-LPC was the most cost-effective diagnostic test. Comparisons among the tests with the same methodology, based on the low ICER values, revealed that IT-LEISH was the most cost-effective test among the RDTs and the Ridascreen Leishmania Ab among the ELISA tests. These results confirm that cost-effectiveness analyses can provide useful information to support the incorporation of new health technologies within a known scenario and willingness to pay threshold. It was observed that tests based on the same methodologies presented different cost-effectiveness ratios for the same group of patients and that different tests should be recommended for different patient groups. DAT-LPC was an important cost-effective strategy for all patients, requiring minimum laboratorial infrastructure, and IT-LEISH was the cost-effective test for VL screening in HIV-uninfected patients. IT-LEISH and DAT-LPC have complementary profiles and should both be provided by the Brazilian health system.Author summary: Human visceral leishmaniasis (VL) is a neglected illness affecting economically vulnerable populations in more than 80 countries. Approximately 90% of the cases registered in Latin American occur in Brazil, where more than 7% of cases are also HIV-infected, and the public health system sustains the costs of illness. Considering the importance of correct diagnosis for VL control and for the optimal use of limited public health resources, we present a cost-effectiveness analysis of the available tests in Brazil up to 2019, stratified according to HIV status. In the different analyses performed, a national noncommercial direct agglutination test (DAT-LPC) and the rapid test IT LEISH were the most cost-effective diagnostic tests. DAT-LPC is especially cost-effective for VL screening among HIV-infected patients, presenting the lowest cost and highest effectiveness. DAT-LPC and IT LEISH are tests that can be performed in laboratories with minimal installed infrastructure, allowing cost-effective strategies for the diagnostic investigation of cases with VL symptoms. The results confirm the importance of cost-effectiveness analyses prior to the incorporation of new health technologies.