Nagy S Schädelin S Hafner P Bonati U Scherrer D Ebi S Schmidt S Orsini AL Bieri O Fischer D 2020 INTRODUCTION The definition of reliable outcome measures is of increasing interest in patients with Duchenne muscular dystrophy (DMD). METHODS In this retrospective study, we analyzed the longitudinal reliability of clinical and radiological endpoints in 29 ambulant patients with DMD. Clinical outcome measures included motor function measure (MFM) and timed function tests, while quantitative MRI data were mean fat fraction (MFF) and T2 relaxation time of thigh muscles. Statistical analysis was based on 3-, 6-, and 12-month follow-up data. RESULTS Quantitative MRI using the MFF was the most sensitive and powerful marker of disease progression with a sample size of four at 1-year follow-up, followed by the D1 domain of MFM (standing and transfer function) with a sample size of 12. DISCUSSION Our data support the longitudinal design of clinical trials over at least 12 months and the combinational use of clinical and radiological surrogate outcome measures. https://sonar.ch/global/documents/231715 eng info:eu-repo/semantics/altIdentifier/doi/10.1002/mus.26690 info:eu-repo/semantics/altIdentifier/pmid/31469921 Muscle & nerve. - 2020 Duchenne muscular dystrophy clinical outcome measure longitudinal analysis motor function measure quantitative muscle MRI sample size Adiposity Adolescent Child Endpoint Determination Follow-Up Studies Humans Longitudinal Studies Magnetic Resonance Imaging Male Movement Muscle, Skeletal Muscular Dystrophy, Duchenne Outcome Assessment, Health Care Reproducibility of Results Retrospective Studies Treatment Outcome Longitudinal reliability of outcome measures in patients with Duchenne muscular dystrophy. http://purl.org/coar/resource_type/c_6501