Prevalence of rheumatic heart disease detected by echocardiographic screening

Background: Epidemiologic studies of the prevalence of rheumatic heart disease have used clinical screening with echocardiographic confirmation of suspected cases. We hypothesized that echocardiographic screening of all surveyed children would show a significantly higher prevalence of rheumatic heart disease. Methods: Randomly selected schoolchildren from 6 through 17 years of age in Cambodia and Mozambique were screened for rheumatic heart disease according to standard clinical and echocardiographic criteria. Results: Clinical examination detected rheumatic heart disease that was confirmed by echocardiography in 8 of 3677 children in Cambodia and 5 of 2170 children in Mozambique; the corresponding prevalence rates and 95% confidence intervals (CIs) were 2.2 cases per 1000 (95% CI, 0.7 to 3.7) for Cambodia and 2.3 cases per 1000 (95% CI, 0.3 to 4.3) for Mozambique. In contrast, echocardiographic screening detected 79 cases of rheumatic heart disease in Cambodia and 66 cases in Mozambique, corresponding to prevalence rates of 21.5 cases per 1000 (95% CI, 16.8 to 26.2) and 30.4 cases per 1000 (95% CI, 23.2 to 37.6), respectively. The mitral valve was involved in the great majority of cases (87.3% in Cambodia and 98.4% in Mozambique). Conclusions: Systematic screening with echocardiography, as compared with clinical screening, reveals a much higher prevalence of rheumatic heart disease (approximately 10 times as great). Since rheumatic heart disease frequently has devastating clinical consequences and secondary prevention may be effective after accurate identification of early cases, these results have important public health implications. N Engl J Med 2007;357:470-6.