Comparison of seven diagnostic tests to detect Trypanosoma cruzi infection in patients in chronic phase of Chagas disease

Objective: To compare the diagnostic performance of seven methods to determine Trypanosoma cruzi infection in patients with chronic Chagas disease. Methods: Analytical study, using the case-control design, which included 205 people (patients with Chagasic cardiomyopathy, n= 100; control group, n= 105). Three enzyme linked immunosorbent assays, one indirect hemagglutination assay and one immunochromatographic test were assessed. Additionally, DNA amplification was performed via the PCR method using kinetoplast and nuclear DNA as target sequences. For the comparative analysis of diagnostic tests, the parameters used were sensitivity, specificity, positive and negative predictive values, Receiver Operator Characteristic (ROC), positive and negative likelihood ratio, as well as κ quality analysis. Results: The commercial BioELISA Chagas test showed the highest sensitivity (98%), specificity (100%), and positive and negative predictive values; additionally, it had the highest discriminatory power. Otherwise, the amplification of T. cruzi DNA in blood samples showed low values of sensitivity (kinetoplast DNA= 51%, nuclear DNA= 22%), but high values of specificity (100%), and moderate to low discriminatory ability. Conclusion: The comparative analysis among the different methods suggests that the diagnostic strategy of T. cruzi infection in patients with chronic Chagas disease can be performed using ELISA assays based on recombinant proteins and/or synthetic peptides, which show higher diagnosis performance and can confirm and exclude the diagnosis of T. cruzi infection. The molecular methods show poor performance when used in the diagnosis of patients with chronic Chagas disease. Objetivo: Comparar la capacidad diagnostica de siete metodos para determinar infeccion por Trypanosoma cruzi, en pacientes con enfermedad de Chagas cronica. Metodos: Estudio analitico de casos y controles, que incluyo 205 personas (pacientes con miocardiopatia chagasica, n= 100; grupo control, n= 105). Se evaluaron tres inmunoensayos enzimaticos, una hemaglutinacion indirecta y una inmunocromatografia. Adicionalmente, se realizo amplificacion de ADN de T. cruzi por reaccion en cadena de la polimerasa utilizando como secuencias diana ADN de kinetoplasto y nuclear. Para el analisis comparativo de las pruebas diagnosticas, los parametros utilizados fueron sensibilidad, especificidad, valores predictivos positivo y negativo, analisis ROC, razon de verosimilitud positiva y negativa, asi como