Prevalence and determinants of rheumatic heart disease among school-going children in Dhanusha district, southern Nepal: a cross-sectional echocardiographic screening study

Rheumatic heart disease (RHD) is a leading preventable cause of cardiac death in children in low and middle-income countries. Nepals epidemiological data come mainly from auscultation surveys that miss subclinical disease, and no echocardiographic screening study had been conducted in Dhanusha district, a densely populated, low-income region in southern Nepal. We aimed to determine the prevalence of borderline and definite RHD among school children (6-16 years) in Dhanusha using the 2012 World Heart Federation (WHF) echocardiographic criteria, identify independent predictors, and quantify school-level clustering via the intraclass correlation coefficient (ICC). In a cross-sectional study (January 2023-December 2024), we screened 4,536 children from 8 public schools selected by four-stage cluster sampling. RHD was classified by WHF 2012 criteria; predictors were identified using random-effects logistic regression with school as random intercept. Ethical approval was from the Nepal Health Research Council (Protocol No. 155/2023). Overall prevalence of borderline or definite RHD was 18.7 per 1,000 (95% CI 15.1-23.0); definite RHD was 6.8 per 1,000 (95% CI 4.7-9.7) and borderline RHD 11.9 per 1,000 (95% CI 9.0-15.5). Prevalence was higher in girls (23.3 per 1,000) than boys (13.6 per 1,000; P=0.02), with the peak in girls aged 10-14 years (26.0 per 1,000). Subclinical disease accounted for 64.7% of cases; auscultation sensitivity was 35.3%. Mitral valve involvement predominated. Female sex was the sole independent predictor (OR 1.60, 95% CI 1.02-2.53; P=0.043). The school-level ICC was 0.19 (95% CI 0.07-0.44; P<0.001), giving a design effect of {approx}109. The echocardiographic RHD burden in Dhanusha (18.7 per 1,000) is the highest documented in Nepal. Two-thirds of cases are subclinical. Female sex and school attended explain a similar amount of variance in RHD risk, supporting school-targeted screening and informing sample size planning for future cluster-based surveillance.