Supplementary Material for: Longitudinal Observation of Children With Achondroplasia: Findings From a Global Natural History Study (ACHieve)

Introduction: The ACHieve study assessed growth velocity, body proportionality, and clinical events in children with achondroplasia not receiving growth-promoting therapy. Methods: ACHieve was a global, longitudinal, prospective, observational study. Children ≤8 years old with achondroplasia were enrolled and evaluated every 6 months for anthropometric parameters and clinical events. Results: ACHieve enrolled 259 children in 15 countries, including 83 from China. Median follow-up was 21 months; median age of diagnosis was approximately 52 weeks in China and 2 weeks elsewhere. Growth parameters were similar regardless of region. Mean annualized growth velocity (AGV) was 9.3 cm/year for males and 10.4 cm/year for females at age 1 and decreased to 4.1 cm/year and 4.6 cm/year, respectively, at age 4. Upper-to-lower-body segment ratio was generally consistent across regions. Overall, 77.2% of participants experienced clinical events, 34.0% of which were considered related to achondroplasia. Two deaths occurred (one accident and one cardiac arrest of unknown origin). Conclusion: ACHieve was one of the largest longitudinal natural history studies of achondroplasia to date and included the largest prospective Chinese achondroplasia cohort. The results demonstrated common trajectories in growth parameters regardless of region, indicating the generalizability of findings.