Study design and sampling:
Suez Canal region representing the eastern section of Egypt was our study area. A cluster random sample was used to ensure full representation of all population varieties of the region. The region was divided into rural and urban areas and then in each area the schools were divided into primary, preparatory and secondary schools. A cluster random samples was chosen from the studied region then a random number of students were included.
Approval of the survey by the ethics committee of the Ministry of Health and Education Ministry of the selected regions were obtained. After obtaining an informed consent from parents or guardians, children at school age (6-18 years) were included in the study as follows:
The region under study was classified into rural and urban areas. All schools in the chosen area were enumerated and classified into either primary, preparatory or secondary. The sample size was distributed proportionally on the three stages according to gender distribution (Table 1). Schools in each stage were chosen on random basis by using computer software (Epi-Info 3.4.3) and the selected schools were visited by the study group.
A total of 1680 students were screened, 119 echocardiographic studies were non-interpretable; so, a total of 1560 studies were evaluated.
Each student from the chosen sample was subjected to 1) Medical history (including demographic data, pervious history of rheumatic fever and any current symptoms) through a verbally administered questionnaire. 2) Detailed cardiac examination and detected murmurs were reported and correlated with echocardiographic findings. 3) A transthoracic Echocardiographic assessment by portable echo machine (Esoate MyLab30) were performed on site by well-trained experts in the standard views.
We developed an abbreviated echocardiographic protocol that took 5–10 min per child and focused on rheumatic pathology of the mitral and aortic valves from the parasternal long axis, apical four and five chamber views, with particular attention being paid to valve morphology on two-dimensional imaging and the degree and extent of mitral and aortic regurgitation, assessed by color flow Doppler imaging. Transvalvular flow was assessed by measuring the peak velocity with continuous wave Doppler imaging. Echocardiographic data was stored on the device to be revised in the echo lab by two separate experts blinded to the clinical data.