Addressing under-registration in Chagas disease mortality: insights from the SaMi-Trop and REDS cohorts

Chagas disease (ChD) remains a significant public health concern in the Americas, with challenges to accurately assessing its mortality burden due to under-reporting and misclassification. This study aimed to analyze mortality patterns of two cohorts of individuals with ChD-one comprising asymptomatic individuals with positive serology (REDS) and another with patients showing Chagas cardiomyopathy (SaMi-Trop)-to propose a method for estimating the potential under-registration of Chagas-related deaths and to find the factors influencing the identification of ChD as the underlying cause of death. We carried out a retrospective analysis of mortality data from these cohorts together with data on the Brazilian Mortality Information System. Causes of death were classified according to ICD-10 codes, and an expert review was used to find possible Chagas-related deaths. Logistic regression was used to explore predictors of ChD identification considering demographic and clinical variables. Of 2,488 patients, 381 died, 28.9% attributed to ChD, predominantly chronic ChD with cardiac involvement (B57.2). Using our method, we estimated a 53.8% potential under-registration rate for possible Chagas deaths. Males were negatively associated with Chagas disease identification, with an odds ratio of 0.52 (95%CI 0.24-1.1). No other significant associations were found, and the overall significance of the model was low. Our findings provide a potential measurement of under-registration, indicating that it may be substantial. These results underscore the need for improved identification and accurate reporting on death certificates. Strengthening the quality of mortality data is essential to understand Chagas-related mortality and guide public health strategies to reduce its impact.