Prevalence of rheumatic heart disease in Zambian school children

Abstract

BackgroundThe large global burden of rheumatic heart disease (RHD) has come to light in recent years following robust epidemiologic studies. As an operational research component of a broad program aimed at primary and secondary prevention of RHD, we sought to determine the current prevalence of RHD in the country’s capital, Lusaka, using a modern imaging-based screening methodology. In addition, we wished to evaluate the practicality of training local radiographers in echocardiography screening methods.MethodsEchocardiography was conducted on a random sample of students in 15 schools utilizing a previously validated, abbreviated screening protocol. Through a task-shifting scheme, and in the spirit of capacity-building to enhance local diagnostic and research skills, general radiographers based at Lusaka University Teaching Hospital (UTH) were newly trained to use portable echocardiography devices. Students deemed as screen-positive were referred for comprehensive echocardiography and clinical examination at UTH. Cardiac abnormalities were classified according to standard World Heart Federation criteria.ResultsOf 1102 students that were consented and screened, 53 students were referred for confirmatory echocardiography. Three students had definite RHD, 10 had borderline RHD, 29 were normal, and 11 students were lost to follow-up. The rates of definite, borderline, and total RHD were 2.7 per 1000, 9.1 per 1000, and 11.8 per 1000, respectively. Anterior mitral valve leaflet thickening and chordal thickening were the most common morphological defects. The pairwise kappa test showed fair agreement between the local radiographers and an echocardiographer quality assurance specialist.ConclusionThe prevalence of asymptomatic RHD in urban communities in Zambia is within the range of results reported in other sub-Saharan African countries using the WHF criteria. Task-shifting local radiographers to conduct echocardiography was feasible. The results of this study will be used to inform ongoing efforts in Zambia to control and eventually eliminate RHD.Trial registrationThe study was registered on clinicaltrials.gov (#NCT02661763).

Prevalence of rheumatic heart disease in North‐Central Nigeria: a school‐based cross‐sectional pilot study

“…We found more cases of borderline RHD than definite RHD, which is consistent with other reports [11,13,25,27–30]. Although children with borderline disease are at substantial risk of progression to definite RHD, the natural history of the disease is still unclear, with limited data on the long‐term outcome [31,32].…”

“…The prevalence in our study compares to reports from Senegal (16.3 per 1000) [28], Ethiopia (19 per 1000) [27] and South Africa (20.2 per 1000) [25]. However, it differed considerably when compared with other African countries which documented prevalence per 1000 schoolchildren of 11.8 in Zambia [29], 31 in Ethiopia [25], 34 in Malawi [30] and 40.2 in Uganda [11]. Several reasons may account for the heterogeneity across reports within the same country and between countries.…”

“…In our study, there were more boys than girls diagnosed with RHD, even though girls made up a larger proportion of our study participants. Even though there have been varying reports on the sex distribution of RHD, most studies have documented that the disease is more common in girls [22,27,29]. The reasons for the female predilection are not clear, although it has been proposed in literature that social factors such as poorer access to health care, repeated exposure to GAS, and genetically mediated immunological factors might predispose girls to autoimmune diseases [33].…”

Echocardiographic screening of 4107 Nigerian school children for rheumatic heart disease

“…The mitral valve was the most commonly affected heart valve. This pattern of rheumatic valve disease in children has been widely reported . Mitral regurgitation remains the commonest cardiac pathological finding in children.…”

“…There are regional variations in prevalence of RHD as risk factors of the disease are largely socio‐economic in nature. The estimated prevalences of RHD among school children in Africa using the WHF criteria and standard echocardiography have ranged from 11.8/1000 to 44.97/1000 and notably the rates are in the double digits per thousand. Our comparison of studies among school children using echocardiographic screening with WHF consensus criteria in different countries of Africa reveal a lower prevalence of RHD in this study compared to findings from other parts of Africa (Table ).…”