Rapid diagnostic tests and ELISA for diagnosing chronic Chagas disease: Systematic revision and meta-analysis

OBJECTIVE

To determine the diagnostic validity of the enzyme-linked immunosorbent assay (ELISA) and Rapid Diagnostic Tests (RDT) among individuals with suspected chronic Chagas Disease (CD).

METHODOLOGY

A search was made for studies with ELISA and RDT assays validity estimates as eligibility criteria, published between 2010 and 2020 on PubMed, Web of Science, Scopus, and LILACS. This way, we extracted the data and assessed the risk of bias and applicability of the studies using the QUADAS-2 tool. The bivariate random effects model was also used to estimate the overall sensitivity and specificity through forest-plots, ROC space, and we visually assessed the heterogeneity between studies. Meta-regressions were made using subgroup analysis. We used Deeks' test to assess the risk of publication bias.

RESULTS

43 studies were included; 27 assessed ELISA tests; 14 assessed RDTs; and 2 assessed ELISA and RDTs, against different reference standards. 51.2 % of them used a non-comparative observational design, and 46.5 % a comparative clinical design ("case-control" type). High risk of bias was detected for patient screening and reference standard. The ELISA tests had a sensitivity of 99% (95% CI: 98-99) and a specificity of 98% (95% CI: 97-99); whereas the Rapid Diagnostic Tests (RDT) had values of 95% (95% CI: 94-97) and 97% (95% CI: 96-98), respectively. Deeks' test showed asymmetry on the ELISA assays.

CONCLUSIONS

ELISA and RDT tests have high validity for diagnosing chronic Chagas disease. The analysis of these two types of evidence in this systematic review and meta-analysis constitutes an input for their use. The limitations included the difficulty in extracting data due to the lack of information in the articles, and the comparative clinical-type design of some studies.

Diagnostic evaluation of two enzyme-linked immunosorbent assay tests for Trypanosoma cruzi infection in a Colombian population

Objective: To evaluate the diagnostic accuracy of two enzyme-linked immunosorbent assay tests to determine Trypanosoma cruzi infection in a Colombian population. Material and methods: Analytical study with case-control design of a diagnostic evaluation. Sensitivity, specificity and diagnostic efficacy of total CHAGATEK ELISA and recombinant CHAGATEK ELISA were determined. Positive predictive value, negative predictive value, and positive and negative likelihood ratios were calculated. The kappa coefficient was found to estimate the concordance between the index and reference tests. The discriminatory capacity of the tests was expressed by the area under the ROC curve. Results: Of the 184 samples included in the study, 99 were negative for T. cruzi and 85 were positive according to the reference tests used. Sensitivity for total and recombinant ELISA was 97.6 % and 98.8 %, respectively; while specificity was 97.0% and 94.9%. The level of concordance of the total and recombinant ELISA was almost perfect and the discriminatory ability of the two tests were good. Conclusions: It was demonstrated that the two tests can confirm and exclude the diagnosis of Chagas disease and have a good diagnostic performance.

Sensitivity and Specificity of two rapid tests for the diagnosis of infection by Trypanosoma cruzi in a Colombian population

Objective

To evaluate diagnostic precision of two rapid diagnostic tests (RDT’s) on patients with chronic Chagas disease.

Methodology

Prospective study with the following inclusion criteria: subjects older than 3 years, signed informed consent. Exclusion criterion: subjects could not have previously received treatment for infection with T. cruzi. The study population were participants in a screening process undertaken in rural and urban zones of the department Boyacá, Colombia. Two RDT’s were performed to all participants: the Chagas Detect Plus InBios (CDP) and the Chagas Stat-Pak (CSP) and as a reference standard the ELISA Chagas III GrupoBios and the Chagas ELISA IgG+IgM I Vircell tests were used. In the case of discordant results between the two ELISA tests, an indirect immunofluorescence was done.

Results

Three hundred-five (305) subjects were included in the study (38 patients with leishmaniasis), of which 215 tested negative for T cruzi and 90 tested positive according to the reference standard. The sensitivity of the RDT’s were 100% (CI 95% 95.9–100), and the specificity of the CDP was 99.1% (CI 95% 96.6–99.8) and for CSP was 100% (CI 95% 98.3–100). The agreement of CDP was 99.5% and for CSP was 100% with Kappa values of (k = 99.1; CI 95% 92.6–99.8%) and (k = 100; CI 95% 94.3–100), respectively. RDT’s did not present cross-reactions with samples from patients who were positive for leishmaniasis.

Conclusions

The findings demonstrate excellent results from the RDT’s in terms of validity, safety, and reproducibility. The results obtained provide evidence for the recommendation for using these tests in a Colombian epidemiological context principally in endemic areas in which laboratory installations necessary to perform conventional tests are not available, or they are scarce and to help in diagnosing chronic Chagas disease in order to provide access to treatment as soon as possible.

Chagas is a disease caused by the parasite Trypanosoma cruzi, and is one of the most important public health concerns affecting the population of Latin America. This disease presents an acute phase that generally goes undiagnosed and a chronic phase with cardiac manifests principally, is diagnosed through serological tests that are not available in the majority of regions endemic for Chagas disease (CD), the results may take weeks to be returned due to logistical and operational reasons that comprise the main obstacles in initiating treatment of the disease. In the present article, quality indices of two RDT’s were evaluated during a field study in the department of Boyacá Colombia, these tests are easy to administer, require only minimal quantities of sample, provide rapid results and do not require electrical equipment or refrigeration. The sensitivity of the two RDT’s was 100% and the specificity of CDP was 99.1% and for CSP was 100% according to reference tests. The results obtained support the recommendation of using RDT’s in order to help diagnose chronic Chagas disease and thus to improve access to treatment for the populations studied as soon as possible.

Estilos de vida en estudiantes de una universidad de Boyacá, Colombia

Introducción. La organización mundial de la salud define el estilo de vida como una forma general de vivir, basada en la interacción entre las condiciones de vida y los patrones individuales de conducta.Objetivo. Identificar estilos de vida saludables en estudiantes universitarios.Materiales y métodos. Estudio en 109 estudiantes, donde se aplicó un instrumento sobre hábitos de vida saludables y medidas antropométricas, de las cuales se obtienen medidas de magnitud, tendencia central y asociación.Resultados. El 38.5% presentó estilo de vida saludable. Sus promedios fueron: edad de 20.75 años, talla de 1.59cm, peso de 56.34kg e índice de masa corporal (IMC) de 22.16 m/t2. Los comportamientos frente a la presencia o no de un estilo de vida saludable fueron estadísticamente significativos: p=0.019 para realizar 30 minutos de actividad física al menos tres veces por semana; p=0.050 si le gustaría realizar más o mejor actividad física regularmente; p=0.046 si ingiere frutas, verduras, granos y alimentos sin procesar; y p=0.008 al dormir entre 7 y 8 horas.Conclusión. Hubo un alto porcentaje de participantes sin estilos de vida saludables, según factores como abandono del domicilio familiar, interacción con personas de diferentes sitios de origen, cambio en hábitos nutricionales, actividades académicas y patrones de sueño y descanso, los cuales interfieren en el intento por mantener una vida saludable.