Upper limb progression in Duchenne muscular dystrophy: Insights from a 36-month longitudinal study using the PUL 20

Abstract

Introduction: Duchenne muscular dystrophy (DMD) is a progressive disorder. This study evaluates upper limb function in DMD patients using the Performance of Upper Limb 2.0 (PUL 2.0) over 36-months.

Methods: Data were collected between 2011 and 2024. Patients with at least 36 months of follow-up were included. Mixed-effects models accounting for repeated measures evaluated 36-month PUL 2.0 changes by entry item and ambulatory status. The entry item assesses the overall upper limb function of the patient. Ambulant patients were defined as those able to walk 10 meters independently, transitioning patients as those who lost ambulation during the duration of the study and non-ambulant as those who had already lost ambulation at baseline.

Results: A total of 219 patients provided 684 paired 36-month assessments. Ambulatory status significantly affected total, shoulder, elbow, and distal scores at baseline. The largest 36-month decline in total scores was found in the 58 transitioning patients (11.62 points, 95%CI = -12.40, 10.84), followed by non-ambulant and ambulant subgroups (n = 116 and n = 86 respectively). The largest declines were seen in patients with baseline entry score of 4 (-11.97, 95% CI = -13.48, -10.46) and 5 (-11.55, 95% CI = -12.46, -10.63), with smaller declines for other entry scores.ConclusionsThe 36-month analysis confirms a clear trend of functional decline across time points, with the transitioning group exhibiting the greatest changes in upper limb function. These findings provide valuable insights for designing trials and offer a reference for long-term comparison of treatment efficacy in both experimental and real-world setting.

Keywords: Duchenne muscular dystrophy; longitudinal study; performance of upper limb; upper limb function.