TY - JOUR AU - Hendrickx, Niels AU - Mentré, France AU - Hamdan, Alzahra AU - Karlsson, Mats O AU - Hooker, Andrew C AU - Traschütz, Andreas AU - Gagnon, Cynthia AU - Schüle-Freyer, Rebecca AU - Synofzik, Matthis AU - Comets, Emmanuelle TI - Comparing randomized trial designs to estimate treatment effect in rare diseases with longitudinal models: a simulation study showcased by Autosomal Recessive Cerebellar Ataxias using the SARA score. JO - BMC medical research methodology VL - 25 IS - 1 SN - 1471-2288 CY - London PB - BioMed Central M1 - DZNE-2025-00920 SP - 179 PY - 2025 AB - Parallel designs with an end-of-treatment analysis are commonly used for randomised trials, but they remain challenging to conduct in rare diseases due to small sample size and heterogeneity. A more powerful alternative could be to use model-based approaches. We investigated the performance of longitudinal modelling to evaluate disease-modifying treatments in rare diseases using simulations. Our setting was based on a model describing the progression of the standard clinician-reported outcome SARA score in patients with ARCA (Autosomal Recessive Cerebellar Ataxia), a group of ultra-rare, genetically defined, neurodegenerative diseases. We performed a simulation study to evaluate the influence of trials settings on their ability to detect a treatment effect slowing disease progression, using a previously published non-linear mixed effect logistic model. We compared the power of parallel, crossover and delayed start designs, investigating several trial settings: trial duration (2 or 5 years); disease progression rate (slower or faster); magnitude of residual error (σ=2 or σ=0.5); number of patients (100 or 40); method of statistical analysis (longitudinal analysis with non-linear or linear models; standard statistical analysis), and we investigated their influence on the type 1 error and corrected power of randomised trials. In all settings, using non-linear mixed effect models resulted in controlled type 1 error and higher power (88 KW - Humans KW - Randomized Controlled Trials as Topic: methods KW - Cerebellar Ataxia: therapy KW - Cerebellar Ataxia: genetics KW - Computer Simulation KW - Longitudinal Studies KW - Disease Progression KW - Research Design KW - Rare Diseases: therapy KW - Treatment Outcome KW - Clinical trial design (Other) KW - Model-based analysis (Other) KW - Non-linear Mixed effect models (Other) KW - Rare disease (Other) KW - Simulation study (Other) LB - PUB:(DE-HGF)16 C6 - pmid:40739200 C2 - pmc:PMC12309037 DO - DOI:10.1186/s12874-025-02626-x UR - https://pub.dzne.de/record/280242 ER -