Background: Chagas disease is caused by the parasite Trypanosoma cruzi. (T. cruzi) and is endemic to Latin America. In the chronic phase of the disease, treatment success is determined by seronegativisation, i.e. disappearance of anti-T. cruzi antibodies.
Objectives: To describe the evolution of conventional serological tests after treatment with nifurtimox or benznidazole in chronically infected subjects.
Methods: The systematic review and meta-analysis protocol was registered in PROSPERO (CRD42012002162). Electronic searches were updated in July 2015.
Primary outcomes were dichotomised as negative or positive: enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence (IIF), and indirect hemagglutination assay (IHA). The Risk of Bias (RoB) was assessed by using Cochrane tools. It was judged as low, moderate, or serious. Discrepancies and queries were resolved through discussion and by contacting the primary authors.
The survival and hazard functions were estimated. The Kaplan-Meier method, Log-rank test, and Cox proportional hazards regression model were applied. A random-effect model was included. Hazard Ratios with 95% of confidence interval were calculated. Subgroup analyses were based on the age at treatment (1-19 years vs >19 years) and the country/region where the infection was acquired (Argentina, Bolivia, Chile, Paraguay-TcV genotype predominant vs Brazil -TcII predominant). SAS software was used. PRISMA-IPD statement was followed.
Results: Individual-level data from 27 out of 48 studies were obtained (1.311 subjects) (Figure 1). RoB was low in 17 studies (63%). Survival plots showed differences between children/adolescents (1-19 years) and adults (Long-rank test <0.001 for ELISA, IIF and IHA test) (Figure 2).
Adjusted Cox model showed interaction between region and age at treatment. There was a higher chance of seronegativisation for subjects treated at 1-19 years compared to adults, especially in the region of Brazil (Table 1).
Conclusions: soccurs earlier in children/adolescents compared to adults. Interaction between age at treatment and region was observed for all outcomes, being stronger for IIF test.