Estimated performance for all index tests (RDTs).

BackgroundChagas disease (CD), caused by the parasite Trypanosoma cruzi, is the most important endemic anthropozoonosis in Argentina. Since 2010, the World Health Organization has highlighted the urgent need to validate diagnostic systems that allow rapid detection of T. cruzi, infection in primary healthcare centers. Serological rapid diagnostic tests (RDTs) for T. cruzi, infection could be used to improve case management, as RDTs do not require specialized laboratories or highly trained staff to use them. We aimed to generate unbiased performance data of RDTs in Argentina, to evaluate their usefulness for improving T. cruzi, diagnosis rates.Methods and principal findingsThis is a retrospective, laboratory-based, diagnostic evaluation study to estimate the clinical sensitivity/specificity of four commercially available RDTs for T. cruzi, using the Chagas disease diagnostic algorithm currently used in Argentina as the reference standard. In total, 400 serum samples were tested, 200 from individuals with chronic T. cruzi infection and 200 from individuals not infected with T. cruzi. All results were registered as the agreement of at least two operators who were blinded to the reference standard results. The sensitivity estimates ranged from 92.5–100% (95% confidence interval (CI) lower bound 87.9–98.2%); for specificity, the range was 76–96% (95% CI lower bound 69.5–92.3%). Most RDTs evaluated showed performances comparable with the reference standard method, showing almost perfect concordance (Kappa 0.76–0.92).ConclusionsOur study demonstrates that, under controlled laboratory conditions, commercially available RDTs for CD have a performance comparable to the Argentinian diagnostic algorithm, which is based on laboratory-based serological tests. For the next stage of our work, the RDTs will be evaluated in real-world settings.</div

Excel spreadsheet containing reference test results.

Excel spreadsheet containing reference test results.</p

Three-way analysis (significant differences in sensitivity and specificity between two methods, in a paired fashion versus the reference algorithm).

Three-way analysis (significant differences in sensitivity and specificity between two methods, in a paired fashion versus the reference algorithm).</p

Number of positive/negative samples needed for a range of estimated sensitivities/specificities.

Number of positive/negative samples needed for a range of estimated sensitivities/specificities.</p

Usability scores of the RDTs evaluated by four operators.

Usability scores of the RDTs evaluated by four operators.</p

Images of each index test verified with the WHO anti-<i>Trypanosoma cruzi</i> I and II antibody reference panel (NIBSC).

a) WL Check Chagas, positive control result; b) WL Check Chagas, negative control result; c) Chagas Rapid First Response, positive control result d) Chagas Rapid First Response, negative control result; e) ACCU-TELL Chagas Cassette, positive control result; f) ACCU-TELL Chagas Cassette, negative control result; g) SD Chagas Ab Rapid, positive control result; h) SD Chagas Ab Rapid, negative control result. (TIF)</p

Manufacturer’s details for the rapid diagnostic tests evaluated.

Manufacturer’s details for the rapid diagnostic tests evaluated.</p

Flowchart depicting study design in conformity with the Standards for Reporting of Diagnostic Accuracy Studies (STARD) guidelines.

Flowchart depicting study design in conformity with the Standards for Reporting of Diagnostic Accuracy Studies (STARD) guidelines.</p