Intra-Rater reliability and validity of outcome measures in Myotonic Dystrophy Type 1

Objective To investigate intra-rater reliability, concurrent- and construct validity of muscle strength, balance, and functional mobility measures in individuals with non-congenital DM1. Methods Seventy-eight adults with non-congenital DM1 participated in visit 1 and 73 of the subjects participated in visit 2 separated by 1-2 weeks. The assessments consisted of muscle strength tests with Hand-Held Dynamometry (HHD) and Stationary Dynamometry in the lower limb. The balance tests comprised of Step Test, Timed Up and Go test, Feet-Together stance, Tandem-Stance, One-Leg-Stance, and modified Clinical Test of Sensory Integration and Balance on a balance platform. The functional mobility tests consisted of the 10-meter Walk Test (10mWT) and 10-times Sit-To-Stand test. Results The HHD and Stationary Dynamometry were sufficiently intra-rater reliable for most muscle groups on a group- (SEM%≤15%) and individual level (MDD95%≤30%), but HHD was most reliable. Stationary Dynamometry ...