Introduction: Progressive degeneration of muscle cells leading to the loss of ambulation and cardiopulmonary compromise are primary features of Duchenne muscular dystrophy (DMD). In-clinic functional measures including the 6-minute walk test (6-MWT) and timed 4-Stair Climb (4-SC) have been used to measure outcomes in clinical and research trial settings. However, these assessments capture a narrow view of a patient’s free-living activity and are challenging due to the requirements of a trained professional, appropriate assessment setting, and patient cooperation. In this study, we seek to characterize the habitual physical activity of non-ambulatory patients at differing stages of disease progression and help establish a reference database for assessing these patients.
Methods: Habitual activity will be measured via continuous actigraphy in 21 non-ambulatory patients with DMD between the ages of 9 and 27 over a period of at least 15 days. Sixteen participants have already completed the study. Nonparametric measures including M10, the activity of the most active 10 hours, and L5, the activity of the least active 5 hours, will be calculated to analyze activity patterns and magnitude.
Results: Preliminary data reveals an average wear compliance of 78.3%. As expected, older participants appear to demonstrate lower activity levels based on preliminary analysis. Our final results will provide further insight into activity levels and disease progression and may help to evaluate the use of actigraphy for assessing DMD patients in clinical and research trial settings.
Discussion: Measures of free-living, habitual physical activity may present a pragmatic method of directly assessing status and disease progression among non-ambulatory DMD patients. We hope to contribute to the development of improved outcome measures and more accurate assessment of patient status. To further study the use of actigraphy among this patient population, additional research is needed to evaluate the barriers and practicality of this method.