Repeat community-based screening for school-age congenital heart disease: impact on the detection of cases requiring treatment in resource-limited settings

BACKGROUND: School-based screening is a critical strategy for detecting congenital heart disease (CHD) in resource-limited regions, yet single-round programs may miss a substantial number of treatable cases. The value of repeat screening in identifying these missed cases remains underexplored. METHODS: As part of the Yunnan Provincial Comprehensive Plan for CHD Prevention and Control, we conducted two rounds of community-based CHD screening using cardiac auscultation followed by portable echocardiography in 23 counties. The first round (2017-2020) screened 1,024,998 children aged 3-18 years, and the second round (2021-2025) screened 1,059,156 children after intervals of 4, 5, 6, or 7 years. Children with CHD requiring treatment were identified and categorized by screening history. RESULTS: The first screening detected 938 cases (prevalence: 0.92/1000), while the second screening detected 557 cases (prevalence: 0.53/1000). Of note, a significant proportion of cases identified in the second round represented missed diagnoses from the first screening. When comparing these missed cases ("previously covered") to the true new cases identified in the second round ("newly covered"), the "newly covered" cases were younger and had lower odds of moderate or great anatomical complexity [adjusted odds ratio (OR) for moderate complexity: 0.58, 95% confidence interval (CI) = 0.36-0.92; adjusted OR for great complexity: 0.29, 95% CI = 0.11-0.71]. CONCLUSIONS: Repeat school-based screening identifies a distinct group of previously missed and newly covered CHD cases, many of which are of higher anatomical complexity and would otherwise remain undiagnosed. These findings underscore the necessity for periodic rescreening to mitigate diagnostic gaps and improve CHD outcomes in resource-limited populations.