Comparison of different criteria for rheumatic heart disease screening: an empirical study in Sierra Leone

Rheumatic heart disease (RHD) affects approximately 40 million people, primarily in low- and middle-income countries. Transthoracic echocardiography is the gold standard for early detection of RHD. Yet, no single echocardiographic finding or combination of findings unequivocally confirms RHD, especially in subclinical stages. As a result, multiple diagnostic guidelines have been proposed. To characterise the echocardiographic RHD findings and criteria included in five of those guidelines; to assess how these diagnostic criteria differ when applied to a concrete population, namely a cohort of high-school students in Sierra Leone; and, as a secondary objective, to provide an initial estimate of the burden of RHD in this country. Our study has two parts. First, we performed a qualitative comparison of five major echocardiographic guidelines, mapping every diagnostic criterion into four roles (required, sufficient, combined, or not considered) for each guideline. Second, we conducted a school-based screening in Sierra Leone. A cohort of 604 asymptomatic female students (aged 10–22 years) underwent a two-phase echocardiographic protocol. We quantified regurgitant jet characteristics and morphological signs according to the criteria of the compared guidelines. Guideline discrepancies were substantial, particularly in jet length thresholds and the diagnostic role of morphological features. These differences shifted individual classifications across categories. In our cohort, 13 students (2.2%) had findings beyond normal under at least one guideline, and positive cases ranged from 0.99% to 2.15% depending on the guideline. Using the World Heart Federation (WHF) 2023 criteria, 1.16% (95% CI: 0.47–2.37) were classified as positive. Variability in echocardiographic criteria influences RHD classification and prevalence estimation. Our empirical study shows that the use of rigid echocardiographic cut-offs may lead to discarding some cases suspicious of RHD, especially in the WHF 2023 screening guideline, because one unfulfilled criterion automatically leads to a negative diagnosis, regardless of the number and relevance of positive findings. We argue that a probabilistic causal model that ponders the numerical measurements and considers correlations among findings would be more appropriate for screening and diagnosis.