The 6-minute walk test as a new outcome measure in Duchenne muscular dystrophy

Area of Science:

• Neurology
• Pediatrics
• Rehabilitation Medicine

Background:

• Walking abnormalities are a significant challenge for individuals with Duchenne muscular dystrophy (DMD).
• The 6-minute walk test (6MWT) is a common functional assessment, but modifications may enhance its utility in specific populations.
• Objective outcome measures are crucial for tracking disease progression and evaluating therapeutic interventions in DMD.

Purpose of the Study:

• To modify and evaluate the performance of the 6-minute walk test (6MWT) as an outcome measure in ambulatory boys with Duchenne muscular dystrophy (DMD).
• To assess the feasibility, safety, reproducibility, and validity of the modified 6MWT in this population.

Main Methods:

• The study involved 21 ambulatory boys with DMD and 34 healthy controls, aged 4 to 12 years.
• Boys with DMD underwent the modified 6MWT twice, approximately one week apart; controls were tested once.
• Data collected included 6-minute walk distance (6MWD) and stride length, with statistical analyses to compare groups and assess test-retest reliability.

Main Results:

• Boys with DMD exhibited a significantly lower mean 6-minute walk distance (6MWD) compared to healthy controls (366 m vs. 621 m, P < 0.0001).
• The modified 6MWT demonstrated high test-retest reliability in boys with DMD (r = 0.91).
• Stride length was identified as a primary determinant of 6MWD in both DMD patients and controls (R(2) = 0.89, P < 0.0001).

Conclusions:

• A modified 6-minute walk test (6MWT) is a feasible, safe, and reproducible outcome measure for evaluating ambulation in boys with Duchenne muscular dystrophy (DMD).
• This modified test effectively documents disease-related functional limitations.
• The modified 6MWT serves as a valuable tool for natural history studies and therapeutic trials in DMD.