Clinical investigation in Duchenne dystrophy: 2. Determination of the "power" of therapeutic trials based on the natural history.
A prospective study of 114 patients with DMD provided data for "power" calculations for future therapeutic trials. There was a decline in strength of 0.4 units per year (on a 0-10 scale). Contractures of the iliotibial bands, hip flexors, and heel cords developed before 6 years. Contractures of other joints accompanied the increased use of wheelchairs. All children walked until 8 years with functional "improvement" between 3-6 years. Children of the same age varied widely in their strength, degree of contracture, and functional abilities. Fifteen percent of the patients appear to have a milder variety of the disease and are termed "outliers." To test a drug which might slow the disease to 25% of its original rate of progression, two groups (placebo and treatment) of 40 patients each would have to be followed for one year.
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D003286:Contracture / Q000188:drug therapy; D006801:Humans; D007223:Infant; D009048:Motor Skills / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009136:Muscular Dystrophies / Q000175:diagnosis / Q000188:drug therapy*; D012119:Respiration / Q000187:drug effects