Rheumatic heart disease screening by echocardiography: the inadequacy of World Health Organization criteria for optimizing the diagnosis of subclinical disease.

BACKGROUND: Early case detection is vital in rheumatic heart disease (RHD) in children to minimize the risk of advanced valvular heart disease by preventive measures. The currently utilized World Health Organization (WHO) criteria for echocardiographic diagnosis of subclinical RHD emphasize the presence of pathological valve regurgitation but do not include valves with morphological features of RHD without pathological regurgitation. We hypothesized that adding morphological features to diagnostic criteria might have significant consequences in terms of case detection rates.

METHODS AND RESULTS: We screened 2170 randomly selected school children aged 6 to 17 years in Maputo, Mozambique, clinically and by a portable ultrasound system. Two different echocardiographic sets of criteria for RHD were assessed: "WHO" (exclusively Doppler-based) and "combined" (Doppler and morphology-based) criteria. Independent investigators reviewed all suspected RHD cases using a higher-resolution, nonportable ultrasound system. On-site echocardiography identified 18 and 124 children with suspected RHD according to WHO and combined criteria, respectively. After consensus review, 17 were finally considered to have definite RHD according to WHO criteria, and 66 had definite RHD according to combined criteria, giving prevalence rates of 7.8 (95% confidence interval, 4.6 to 12.5) and 30.4 (95% confidence interval, 23.6 to 38.5) per 1000 children, respectively (P<0.0001, exact McNemar test).

CONCLUSIONS: Important consideration should be given to echocardiographic criteria for detecting subclinical RHD because the number of cases detected may differ importantly according to the diagnostic criteria utilized. Currently recommended WHO criteria risk missing up to three quarters of cases of subclinically affected and therefore potentially treatable children with RHD.