The 6-Minute Walk Test is the strongest outcome measure for DMD (currently). A recent systematic review goes over a few outcome measures with some cut-offs (Landfeldt, 2024).
Here are the ones I know best:
6 Minute Walk Test
• <350 meters is usually the threshold; boys tend to lose ambulation within 24 months when they are below this point
• Rapid decline of >30 meters/year also predicts transition toward loss of ambulation
• Landfeldt E, Alemán A, Abner S, et al. Predictors of Loss of Ambulation in Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis. J Neuromuscul Dis. 2024;11(3):579-612. doi:10.3233/JND-230220.
North Star Ambulatory Assessment
• Lower total scores (usually <20-22) are associated with faster decline
• Inability to perform key items (run, jump, rise from floor) strongly predicts near term loss of ambulation
• Landfeldt article
• Mazzone ES, Pane M, Sormani MP, et al. 24 month longitudinal data in ambulant boys with Duchenne muscular dystrophy. PLoS One. 2013;8(1):e52512. doi:10.1371/journal.pone.0052512
Timed Function Tests often decline before 6MWT drops dramatically
• Time to Rise from Floor, Time to Climb 4 Stairs, 10-Meter Walk/Run Time
• Rise from floor >6-8 seconds predicts decline, loss of ability to rise independently strongly predicts loss of ambulation within one year
• Mazzone ES, Coratti G, Sormani MP, et al. Timed Rise from Floor as a Predictor of Disease Progression in Duchenne Muscular Dystrophy: An Observational Study. PLoS One. 2016;11(3):e0151445. Published 2016 Mar 16. doi:10.1371/journal.pone.0151445
