Author + information
- Mariana Mirabel, MD, PhD∗ (, )
- Muriel Tafflet, PhD,
- Baptiste Noël, MD,
- Tom Parks, MD, PhD,
- Corinne Braunstein, MD,
- Bernard Rouchon, MD,
- Eloi Marijon, MD, PhD and
- Xavier Jouven, MD, PhD
- ↵∗Paris Cardiovascular Research Centre, Inserm U970, Hôpital Européen Georges Pompidou, 56 rue Leblanc, 75737 Paris Cedex 15, France
Rheumatic heart disease (RHD) remains the leading acquired heart disease in the young, causing >350,000 premature cardiovascular deaths each year worldwide (1). Detecting the condition early is useful, permitting prompt initiation of secondary prophylaxis with penicillin, thereby avoiding progression of heart valve disease. The advent of echocardiographic screening in endemic areas has led to a new epidemiological pyramid-type model combining subclinical RHD at the base and symptomatic RHD leading to hospital admission at the top (2). There are, however, no data published to date to support this model. Our aim was to report the prevalence of subclinical and of symptomatic RHD in New Caledonia.
New Caledonia is a high-income nation in the South Pacific where RHD remains endemic among indigenous populations. For the present study, cases were identified from 2 sources. First, patients with subclinical disease were identified through a national school-based screening campaign, a government-funded initiative targeting primary schoolchildren in the fourth grade (ages ∼9 to 10 years). Second, hospitalized patients with symptomatic disease were identified respectively at Centre Hospitalier Territorial de Nouvelle Calédonie, to which, as the only institution in the country providing specialist services in cardiology and pediatrics, all patients with symptomatic RHD are referred.
Using these data, we estimated the prevalence among school-aged children of both subclinical RHD and symptomatic RHD (severity sufficient to require hospitalization). Prevalence was computed with exact 95% confidence intervals and using estimates of population size published in 2009 by the New Caledonian Bureau of Statistics as the denominator for the hospital-based data. All data were managed, controlled, and analyzed with SAS version 9.4 (SAS Institute, Cary, North Carolina).
The school-based screening campaign used a 2-step process to identify cases. All primary schoolchildren in the fourth grade for whom parental consent was obtained underwent screening echocardiography. If heart disease was suspected, the child underwent further echocardiography by an experienced cardiologist. Among the 18,621 schoolchildren targeted by the campaign from 2008 to 2011, 17,287 (92.8%) were ultimately screened. There were 85 children (0.49%) with histories of acute rheumatic fever or known RHD. Among 15,047 children ages 9 to 10 years, 1,340 (7.7%) were referred for a second opinion on nonportable equipment, of whom 335 (25.0%) did not attend the free-of-charge clinic. In the study, 130 children were diagnosed with subclinical RHD. The overall prevalence of subclinical RHD was 8.6 per 1,000 children 9 to 10 years of age (95% confidence interval: 7.5 to 10.7). Prevalence rates by year of the screening campaign are shown in Table 1. None of the children with subclinical RHD was subsequently admitted to the hospital.
Potential hospitalized patients were detected retrospectively from a database of International Classification of Diseases–coded discharge diagnoses covering 2008 to 2011 using codes for RHD and acute rheumatic fever. To confirm or refute RHD, the clinical records of each case were reviewed and reevaluated with respect to standardized echocardiographic criteria (3). Eighty-four children ages 9 to 10 years were diagnosed with symptomatic RHD from 2008 to 2011 (Table 1).
By combining information from school- and hospital-based studies, our study provides valuable insight into the relationship of clinical and subclinical RHD in this population. The data are especially interesting because of the unusual juxtaposition of high rates of RHD in a population with high levels of school attendance (increasing the accuracy of school-based surveys) and ready access to hospital services (increasing the accuracy of hospital-based analyses). In both studies, prevalence was higher among indigenous populations (data not shown). The echocardiography-based survey prevalence estimates in children ages 9 to 10 years were at least 3- to 5-fold higher than figures driven from the hospital cohort, a result that is in keeping with the recently advanced model incorporating asymptomatic and symptomatic RHD (2). A major challenge remains, however, in identifying patients with subclinical disease at risk for progression of symptomatic disease. Indeed, it is likely that significant numbers of patients with subclinical disease never become symptomatic (4), while a proportion of patients with clinically apparent disease (e.g., with a murmur) never present with cardiovascular events (5). We acknowledge that a number of subclinical cases may have gone undiagnosed given that a number of patients with suspected RHD did not attend the clinic. Furthermore, children not captured by the survey were by their sociodemographic characteristics at high risk for RHD. The ratio of subclinical to symptomatic RHD may therefore be higher than 3 to 5. Overall, our results encourage further efforts to assess the role of echocardiography as a screening tool in endemic, and often resource-deprived, settings.
Please note: Dr. Mirabel has received funding from Fédération Française de Cardiologie, Fondation Lefoulon Delalande, and Fondation pour la Recherche Médicale. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. The authors are grateful to Aurélia Jewiné and Nathalie Simon for their work in collecting the hospital data. Corinne Robillard, Agnès Germain, and Nina Guillot provided access to the national survey at Agence Sanitaire de Nouvelle Calédonie.
- American College of Cardiology Foundation