Performance of Upper Limb module for Duchenne muscular dystrophy.

Area of Science:

• Neurology
• Musculoskeletal Disorders
• Clinical Measurement

Background:

• Duchenne muscular dystrophy (DMD) significantly impacts upper limb function.
• Accurate and sensitive measurement tools are crucial for tracking disease progression and treatment efficacy in DMD.
• The Performance of Upper Limb (PUL) scale is used to assess upper limb function in DMD patients.

Purpose of the Study:

• To compare the measurement properties of the Performance of Upper Limb (PUL) versions 1.2 and 2.0.
• To evaluate the longitudinal performance of both PUL versions in Duchenne muscular dystrophy patients.
• To determine if PUL 2.0 offers enhanced ability to detect changes in motor performance over time.

Main Methods:

• Rasch analysis was applied to data from three centers to assess construct validity.
• Dual data from existing natural history studies were used for longitudinal comparison.
• Change scores across different domains were compared between PUL 1.2 and PUL 2.0.

Main Results:

• Rasch analysis confirmed that both PUL 1.2 and 2.0 measure the same underlying construct of upper limb motor performance.
• PUL 2.0 demonstrated a better fit to the motor performance construct and superior ability to detect change at 12 months across all ability levels compared to PUL 1.2.
• Both versions detected changes in all domains over a 2-year period, with PUL 2.0 showing enhanced measurement qualities.

Conclusions:

• The revised PUL 2.0 scale maintains construct validity while enhancing measurement sensitivity for upper limb function in DMD.
• PUL 2.0 is a more effective tool for detecting longitudinal changes in motor performance in Duchenne muscular dystrophy patients.
• Simplifying the scoring in PUL 2.0 preserves its clinical utility and improves its psychometric properties.