LAUSR

Congenital heart disease (CHD) is an important contributor to morbidity and mortality in children, and the global burden of this illness has raised unique challenges to the healthcare system [1, 2]. China is among the countries with the highest burden of this disorder despite having achieved huge advances in cardiac surgery or interventional therapies in CHD during the past two decades [3]. Interestingly and unexpected is the lower prevalence rate of CHD reported in China. The prevalence of CHD at live birth is estimated to be 9.4 per 1000 worldwide [4]. However, this figure is much lower in China, with only 4.9 per 1000 live births between 2015 and 2019 [5]. Furthermore, contrary to the general understanding [2], rural areas in China have a lower CHD prevalence than urban areas [5]. This counterintuitive discrepancy is likely attributed to unrecognized cases of CHD [3], which is still a major public health burden in many developing countries [6–8]. Even though neonatal CHD screening has been adopted for the universal newborn screening program in China since 2018 [10, 11], a longer period may be required for its benefits to come to fruition in rural areas. Late presentation with severe complications (such as heart failure, endocarditis, or irreversible pulmonary hypertension) due to delayed diagnosis has been known to contribute significantly to adverse outcomes, which may largely explain the high disease burden in these settings. Accurate estimates of unrecognized CHD, thus, could contribute to quantifying unmet health needs for diagnosis and treatment. School age has been suggested to be a period optimal for CHD screening to detect previously unrecognized CHD in rural areas [6, 12]. However, data on the epidemiological survey of CHD among school-age children are still sparse. We are aware of only five studies that have reported the CHD prevalence among school-age children in the whole population, ranging from 0.5 to 2.1 per 1000 [14–18]. As to unrecognized CHD, the global estimate in a recent systematic review was 1.4 per 1000 [13]. Of note, only nine studies were available for this estimate, with four of them from Thailand. Nonetheless, almost all studies have used a traditional survey strategy, where an echocardiographic examination was performed only in suspected cases after clinical assessment. In China, the largest survey of 540,574 students conducted in urban areas has reported a prevalence of 2.1 per 1000, but with only 2.7% undergoing echocardiography [15]. This would inevitably lead to an underestimation of the true prevalence of CHD. On the other hand, although four studies based on a systematic echocardiographic approach reported a higher prevalence (ranging from 6.6 to 19.6 per 1000) [19–22], these studies were sample surveys with a limited sample size between 357 and 4213. Although less likely to be practical or affordable under most current health care systems, echocardiographic screening of all children would provide an accurate estimate of the unrecognized CHD. Our recent work provided such an estimate in a selected rural area through echocardiographic screening of 21,861 children aged 5–18 years in one town and four townships in Luchun County (totaling 99.2% of all school-age children) [23]. Among the 285 children with CHD identified in the study, only 33 already had parent-reported CHD; the remaining 252 were unrecognized cases. In other words, these 252 were diagnosed for the first time during our screening. Thus, our data showed a prevalence rate of 11.5 per 1000 children, tenfold the global estimate of unrecognized CHD based on the traditional survey strategy. Moreover, unlike previously thought, more than 70% of unrecognized CHD were moderate cases who are physically appreciable and require treatment or were severe cases who already had heart failure symptoms, including cyanosis, fatigue, decreased activity, and growth retardation. * Guo-Ying Huang [email protected]