***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Echocardiography is emerging as a screening tool for  rheumatic heart disease ( RHD ) in endemic regions . The vast majority of surveys have been limited to children . We ought to appreciate the interest of including adolescents in their late teens in such school screening programmes . METHODS School-based echocardiography cross-sectional survey conducted in Dakar , Senegal ( March 2010 ) . A total of 2004 school attendees were r and omly selected and enrolled in the study , among which 1116 were aged 5 - 15 years old ( group 1 ) , and 888 were 16 - 18 years old ( group 2 ) .  Case detection rates and phenotype of RHD were compared according to age groups . RESULTS A total of 22 youngsters were suspected by on-site  echocardiography  , 12 in group 1 and 10 in group 2 . Among the 12 RHD cases suspected on-site in group 1 , 6 ( 50 % ) were eventually considered as confirmed RHD , compared to 9 out of 10 ( 90 % ) in group 2 , giving prevalence rates of 5.4 ( CI 95 % 2.0 - 11.7 ) and 10.1 ( CI 95 % 4.6 - 19.2 ) per 1000 in group 1 and group 2 , respectively . The proportion of marked/advanced lesions was 33 % in group 1 , and 89 % in group 2 ( p=0.08 ) . Mean concordance rates between the 3 review ers were 40 % for group 1 , compared to 93 % in group 2 ( p=0.05 ) . CONCLUSIONS Extension of screening to adolescents in their late teens should be considered with interest in the light of the higher prevalence of the disease and relative clarity of sub clinical cardiac lesions that could be more easily detected in the field While rheumatic heart disease ( RHD ) is a treatable disease nearly eradicated in the United States , it remains the most common form of acquired heart disease in the developing world . This study used echocardiographic screening to determine the prevalence of RHD in children in American Samoa . Screening took place at a subset of local schools . Private schools were recruited and public schools underwent cluster r and omization based on population density . We collected survey information and performed a limited physical examination and echocardiogram using the World Heart Federation protocol for consented school children aged 5–18 years old . Of 2200 students from two private high schools and two public primary schools , 1058 subjects consented and were screened . Overall , 133 ( 12.9 % ) children were identified as having either definite ( 3.5 % ) or borderline ( 9.4 % ) RHD . Of the patients with definitive RHD , 28 subjects had abnormal mitral valves with pathologic regurgitation , three mitral stenosis , three abnormal aortic valves with pathologic regurgitation , and seven borderline mitral and aortic valve disease . Of the subjects with borderline disease , 77 had pathologic mitral regurgitation , 12 pathologic aortic regurgitation , and 7 at least two features of mitral valve disease without pathologic regurgitation or stenosis . Rheumatic heart disease remains a major cause of morbidity and mortality worldwide . The prevalence of  RHD in American Samoa ( 12.9 % ) is to date the highest reported in the world literature . Echocardiographic screening of school children is feasible , while reliance on murmur and Jones criteria is not helpful in identifying children with RHD Rheumatic heart disease ( RHD ) results in morbidity and mortality that is disproportionate among individuals in developing countries compared to those living in economically developed countries . The global burden of disease is uncertain because most previous studies to determine the prevalence of RHD in children relied on clinical screening criteria that lacked the sensitivity to detect most cases . The present study was performed to determine the prevalence of RHD in children and young adults in León , Nicaragua , an area previously thought to have a high prevalence of RHD . This was an observational study of 3,150 children aged 5 to 15 years and 489 adults aged 20 to 35 years r and omly selected from urban and rural areas of León .  Cardiopulmonary examinations  and  Doppler echocardiographic studies  were performed on all subjects . Doppler echocardiographic diagnosis of RHD was based on predefined consensus criteria that were developed by a working group of the World Health Organization and the National Institutes of Health . The overall prevalence of RHD in children was 48 in 1,000 ( 95 % confidence interval 35 in 1,000 to 60 in 1,000 ) . The prevalence in urban children was 34 in 1,000 , and in rural children it was 80 in 1,000 . Using more stringent Doppler echocardiographic criteria design ed to diagnose definite RHD in adults , the prevalence was 22 in 1,000 ( 95 % confidence interval 8 in 1,000 to 37 in 1,000 ) . In conclusion , the prevalence of RHD among children and adults in this economically disadvantaged population far exceeds previously predicted rates . The findings underscore the potential health and economic burden of acute rheumatic fever and RHD and support the need for more effective measures of prevention , which may include safe , effective , and affordable vaccines to prevent the streptococcal infections that trigger the disease BACKGROUND Auscultation-based surveys in Ethiopia conducted in the late 1990 's reported a rural prevalence of 4.6/1000 and an urban prevalence of 6.4/1000 of rheumatic heart disease ( RHD ) . With echo-based screening , we aim ed to estimate the national prevalence of RHD in school children by taking school-based sample s from six regions across the country using the 2012 World Heart Federation echocardiographic criteria . PATIENTS AND METHODS We conducted a cross-sectional echocardiographic screening of RHD in school children aged 6 - 18years from 28 r and omly selected primary and secondary schools found in six different geographic regions of Ethiopia . We used the st and ardized WHF echocardiographic criteria . RESULTS A total of 3238 children ( 48.5 % females ) were screened . The mean age was 13.2±3.2years . Of these , 44 patients ( 1.4 % ) met the WHF criteria for definite RHD , while 15 ( 0.5 % ) met the criteria for borderline disease , yielding a prevalence of 19 [ 13.9 - 23.4 , 95 % CI ] cases per 1000 school children between the ages of 6 - 18years . The majority of those who tested positive were girls ( 26/44 ) . The prevalence was lowest in children aged 6 - 9years and otherwise uniformly distributed across ages 10 - 18years . Definite RHD involved the mitral valve in 42 subjects , 39 of whom had mitral regurgitation and 3 with mitral stenosis . The aortic valve was affected in 6 children . The ratio of definite to borderline cases was 2.9 . CONCLUSION This study demonstrated a consistent pattern of high prevalence of asymptomatic RHD with definite disease predominating over borderline involvement across six regions of Ethiopia BACKGROUND Echocardiography has been proposed as a method to screen children for rheumatic heart disease . The World Heart Federation has established guidelines for echocardiographic screening . In this study , we describe a rapid echocardiogram screening protocol according to the World Heart Federation guidelines in Samoa , endemic for rheumatic heart disease . METHODS We performed echocardiogram screening in schoolchildren in Samoa between 2013 and 2015 . A brief screening echocardiogram was performed on all students . Children with predefined criteria suspicious for rheumatic hear diseases were referred for a more comprehensive echocardiogram . Complete echocardiograms were classified according to the World Heart Federation guidelines and severity of valve disease . RESULTS Echocardiographic screening was performed on 11,434 children , with a mean age of 10.2 years ; 51 % of them were females . A total of 558 ( 4.8 % ) children underwent comprehensive echocardiography , including 49 students who were r and omly selected as controls .  Definite rheumatic heart disease was observed in 115 students ( 10.0 per 1000 ) : 92 students were classified as borderline ( 8.0 per 1000 ) and 23 with CHD . Advanced disease was identified in 50 students ( 4.4 per 1000 ) : 15 with severe mitral regurgitation , five with severe aortic regurgitation , 11 with mitral stenoses , and 19 with mitral and aortic valve disease . CONCLUSIONS We successfully applied a rapid echocardiographic screening protocol to a large number of students over a short time period - 28 days of screening over a 3-year time period - to identify a high prevalence of rheumatic heart disease . We also reported a significantly higher rate of advanced disease compared with previously published echocardiographic screening programmes Background The objective of the study was to evaluate the implication s of different classifications of rheumatic heart disease on estimated prevalence , and to systematic ally assess the importance of incidental findings from echocardiographic screening among schoolchildren in Peru . Methods We performed a cluster r and omized observational survey using portable echocardiography among schoolchildren aged 5 to 16 years from r and omly selected public and private schools in Arequipa , Peru . Rheumatic heart disease was defined according to the modified World Health Organization ( WHO ) criteria and the World Heart Federation ( WHF ) criteria . Findings Among 1395 eligible students from 40 classes and 20 schools , 1023 ( 73 % ) participated in the present survey . The median age of the children was 11 years ( interquartile range [ IQR ] 8–13 years ) and 50 % were girls . Prevalence of possible , probable and definite rheumatic heart disease according to the modified WHO criteria amounted to 19.7/1000 children and ranged from 10.2/1000 among children 5 to 8 years of age to 39.8/1000 among children 13 to 16 years of age ; the prevalence of borderline/definite rheumatic heart disease according to the WHF criteria was 3.9/1000 children . 21 children ( 2.1 % ) were found to have congenital heart disease , 8 of which were referred for percutaneous or surgical intervention . Conclusions Prevalence of RHD in Peru was considerably lower compared to endemic regions in sub-Saharan Africa , southeast Asia , and Oceania ; and paralleled by a comparable number of undetected congenital heart disease . Strategies to address collateral findings from echocardiographic screening are necessary in the setup of active surveillance programs for RHD . Trial Registration Clinical Trials.gov identifier : Objective To study the prevalence and medium term outcome of sub clinical rheumatic heart disease ( RHD ) in India . Design Cross sectional echocardiographic screening study . Setting School children aged 5–15 years living in rural areas of north India . Patients A cross sectional echocardiographic screening study was carried out among 6270 r and omly selected school children aged 5–15 years ( 10.8±2.6 years ; 52.7 % male ) . Of all the abnormal cases , 100 children ( 78 % ) were restudied at a mean follow-up of 15.4±6.6 months . Intervention Echocardiographic screening . Main outcome measure Echocardiography – Doppler criteria based prevalence of RHD . Results Clinical examination detected mitral regurgitation in five patients and the estimated prevalence of clinical RHD was 0.8/1000 school children . Echocardiography – Doppler diagnosed RHD in 128 cases , giving a prevalence of 20.4/1000 school children ( 95 % CI 16.9 to 23.9/1000 children ) . On multivariate analysis , older age ( OR 1.93 , 95 % CI 1.29 to 2.88 ; p=0.001 ) , female sex ( OR 1.84 , 95 % CI 1.25 to 2.72 ; p=0.002 ) and government funded school student , which is a surrogate measure of lower socioeconomic status ( OR 1.55 , 95 % CI 1.02 to 2.34 ; p=0.039 ) were found to be independent predictors of RHD . On follow up , the severity of sub clinical RHD was non-progressive in 68 children ( 68 % ) while it worsened in four ( 4 % ) and regressed in 28 children ( 28 % ) . Conclusions The prevalence of RHD is several fold higher using echocardiographic screening compared with clinical examination . The prevalence is higher among girls and children of lower socioeconomic status . In the majority of cases , sub clinical RHD appears to be non-progressive on medium term follow up . Routine echocardiographic screening may be indicated in population s at high risk of RHD Background — Historically , sub-Saharan Africa has had the highest prevalence rates of clinical ly detected rheumatic heart disease ( RHD ) .  Echocardiography-based screening improves detection of RHD in endemic regions . The new 
    Output:
    
Definite RHD tends to progress or remain stable over time