It has been estimated that RHD affects over 32 million people worldwide, with the vast majority of cases occurring in the developing world. RHD is the most common cardiovascular disease in children and young adults and is a major cause of death in children above the age of 5 in many parts of the developing world, particularly sub-Saharan Africa.
RHD results from repeated attacks of acute rheumatic fever (ARF). ARF is a systemic inflammatory disease occurring mainly in children, characterized by fever, painful joints, and heart, skin, and neurological manifestations. ARF is linked with preceding Group A streptococcal (GAS) throat infections, which, if left untreated, carry an estimated 2-3% risk of developing ARF.
The pathologic hallmark of RHD is classically a valvulitis that affects mostly the mitral and/or aortic valves. Inflammation of the myocardium and pericardium may exacerbate the effects of valvular insufficiency, resulting in congestive heart failure, stroke and other complications. Over time, severe disability or death can ensue, especially in developing countries where the management of RHD patients is challenging and surgical interventions are not readily available.
ARF and RHD are diseases of poverty, especially in countries with limited healthcare systems. GAS thrives in situations of over-crowding where poor nutrition and sanitation are common and where medical treatment for sore throat is not readily available. For these reasons, RHD is endemic in many parts of the developing world, particularly sub-Saharan Africa, while it almost disappeared from most parts of the developed world (except for indigenous populations in some countries). It should be noted that the initial decline of ARF/RHD in the US and Europe most likely was due to improved living conditions and hygiene (primordial prevention), since it predated the introduction of penicillin.
RHD is one of few truly preventable chronic diseases. Currently, many sub-Saharan African countries do not focus efforts on primary and secondary prevention due to lack of resources. The long-term goal of an ongoing effort in Zambia is to develop capability to provide effective primary and secondary prevention of RHD, with the ultimate goal of eliminating new cases.
Although RHD is associated with major morbidity and mortality in children and young adults, until recently few reliable estimates of the burden from this disease existed in sub-Saharan Africa. Population-based screening for RHD had been limited to clinical examination, which does not detect early RHD in which a heart murmur or other clinical signs of disease are absent (subclinical disease). Estimates of RHD prevalence based on clinical surveillance methods compared with screening echocardiography have been shown to result in gross underestimates (up to 10 fold).
With advances in portable ultrasonography and the development of international guidelines for echocardiographic diagnosis of RHD, population-based screening for subclinical RHD is now possible. Using this new approach, recent studies in countries with similar geographic and demographic profiles to Zambia showed that RHD prevalence in sub-Saharan Africa is much higher than previously thought; approximately 1-3% of schoolgoing children appear to have evidence of definite or borderline RHD.
In this study, the investigators will apply echocardiographic screening methods to determine the prevalence of RHD in a large population of Zambian school children. Data on the disease burden of RHD in Zambia will be used to inform the design and conduct of health programs to combat RHD.
The proposed study will involve a sample size of at least 1,024 students in grades 7-12 in fifteen randomly selected schools in Lusaka. Each student that meets inclusion criteria will undergo a focused history and physical examination and rapid echocardiographic screening. The fifteen schools involved in the study will be identified as a random sample from 119 currently operating primary and secondary schools in Lusaka using standard sampling methods. Approximately 60-80 students from each school will be screened. The screening will be conducted using an ultraportable ultrasound device and an abridged screening protocol that has been validated in a separate study by investigators at the University of Cape Town in South Africa. Children with suspected ARF or RHD will be followed up at UTH for an in-depth clinical examination and quantitative electrocardiogram. Children with definite or borderline RHD according to World Heart Federation Criteria will be offered secondary penicillin prophylaxis according to national guidelines in Zambia. Children with sore throat will be referred for evaluation and treatment with penicillin according to national guidelines for primary prevention of RHD at UTH or a local health clinic.
An additional feature of this study is the development of local technical expertise to conduct echocardiographic screening. This is necessary because few health workers in Lusaka are proficient in cardiac echocardiography. The feasibility of task-shifting echocardiographic screening to non-expert health workers has been demonstrated in similar settings. The investigators will therefore train radiography technicians who have little or no previous experience with echocardiography to conduct school-based screening.
Given that radiographers will be newly trained to conduct screening echocardiography, two mechanisms will be implemented to help ensure successful school screening: (1) international echocardiography technician experts will periodically accompany study staff during school screenings to support the work of local radiographers; and (2) all screening echocardiograms will be de-identified and reviewed remotely by a professional third-party echocardiographer who will report back on any echocardiograms that are determined to be read as falsely negative by the field team.
Most data that will be obtained for the study will be entered through mobile electronic devices (computer tablets) at the time of capture into a digital system ("eRegister") that will be developed specifically for the study. The system uses DiMagi's "CommCare" platform, which includes a customizable mobile health data collection application and an online portal, "CommCareHQ," for secure data viewing and reporting. All access to the CommCare platform including mobile submissions will be done over HTTPS (hypertext transfer protocol) and will be cryptographically secure. Mobile devices will be password-locked and accessible only by the study staff member to whom the device is allocated. Once data are submitted to the server they will be automatically erased from the mobile device. Echocardiograms will also be saved in the system; images and videos will be temporarily stored on the hard drive of the ultrasound device and then transferred to the eRegister.
