Outcomes of Latent Rheumatic Heart Disease: External Validation of a Simplified Score in Patients with and Without Secondary Prophylaxis

Background: Secondary antibiotic prophylaxis reduces progression in children with latent rheumatic heart disease (RHD). However, nearly half of children show improvement with or without prophylaxis. Improved risk stratification could refine prophylaxis recommendations following positive screening echo. We aimed to validate a previously developed echo risk score to predict mid-term RHD outcomes among children with latent RHD. Methods: Our population included children who completed the GOAL Trial, a randomized controlled trial of secondary antibiotic prophylaxis among children with latent RHD in Uganda. These children underwent echo at enrollment and study completion, with rigorous blinded adjudication by a 4-member panel to establish diagnosis. We applied a point-based risk score developed from prior Brazilian and Ugandan cohorts, consisting of 5 variables (mitral valve (MV) anterior leaflet thickening (3 points), MV excessive leaflet tip motion (3), MV regurgitation jet length ≥2 cm (6), aortic valve focal thickening (4) and any aortic regurgitation (5)) to predict unfavorable outcome, defined as progression of diagnostic category (borderline to definite, definite mild valvular disease to definite moderate/severe disease) or remaining with definite RHD. Results: At total 801 patients (626 borderline and 175 definite RHD, mean age 12.5±2.9 years) were included, with median follow-up of 24 months. RHD progression was observed in 3 patients in the Penicillin group, vs. 33 in the control group, and overall, 386 patients regressed and 377 remained stable. The echo score was strongly associated with unfavorable outcome (OR: 1.25, 95% CI 1.15 - 1.36, p<0.001). Unfavorable outcome rates in low (≤6 points), intermediate (7 - 9) and high-risk (≥10) children at follow-up were 12.2%, 31.1%, and 42.2%, (p<0.001) respectively, with area under the ROC curve of 0.64 (95% CI 0.59 - 0.69). Among children without prophylaxis, the score had a similarly good performance: OR: 1.24 (95% CI 1.12 - 1.39), area under the ROC curve: 0.64 (95% CI 0.58 - 0.70). Conclusions: The simple risk score provided an accurate prediction of RHD status at 2-years, showing a good performance in a population with milder RHD phenotypes, with a potential value for global risk stratification.