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Updated: May 9, 2026
Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy
Published on: January 12, 2019
The 6-Minute Walk Test and Person-Reported Outcomes in Boys with Duchenne Muscular Dystrophy and Typically Developing
Erik Henricson1, Richard Abresch1, Jay J Han1
1Department of Physical Medicine and Rehabilitation, University of California, Davis, Sacramento, California, USA.
Insights
Minimal clinically important differences in Duchenne muscular dystrophy (DMD) vary by functional ability. Smaller 6-minute walk test (6MWT) gains yield meaningful quality of life improvements in lower-functioning individuals with DMD.
Area of Science:
- Pediatric Orthopedics
- Neuromuscular Disorders
- Clinical Outcome Measurement
Background:
- Establishing minimal clinically important differences (MCID) for the 6-minute walk test (6MWT) in Duchenne muscular dystrophy (DMD) is crucial for assessing treatment efficacy.
- Current data lacks clear anchors for a 30-meter longitudinal change in 6MWT as an MCID, especially concerning patient-reported outcomes (PROs) across different ambulatory abilities.
Purpose of the Study:
- To correlate measures of walking ability and patient-reported outcomes (PROs) in ambulatory Duchenne muscular dystrophy (DMD) patients.
- To determine if MCIDs of PROs contribute to different estimates of 6-minute walk distance (6MWD) change at varying functional levels.
- To establish clinically meaningful changes in PROs and their relationship to 6MWD in DMD.
Main Methods:
- Correlated the 6-minute walk test (6MWT), 10-meter run/walk velocity, PedsQL, and POSNA Pediatric Outcomes Data Collection Instrument (PODCI) in 24 ambulatory DMD patients and 36 controls.
- Analyzed 1-year changes in these measures and their correlations.
- Assessed MCIDs for PROs and their impact on 6MWD change estimates.
Main Results:
- Significant differences in PedsQL and PODCI scores were observed between DMD patients and controls (p<0.00001).
- PODCI transfer/mobility scores showed the strongest correlation with 6MWD and 10-meter run/walk velocity in DMD (r=0.79 and r=0.76, respectively).
- One-year changes in 6MWD, 10-meter run/walk velocity, and PODCI scores exceeded MCID. 6MWD change strongly correlated with PODCI changes (r=0.76-0.93).
Conclusions:
- Smaller increases in 6-minute walk distance (6MWD) correlate with meaningful quality of life improvements at lower functional levels in Duchenne muscular dystrophy (DMD).
- Larger 6MWD gains may be required to achieve similar quality of life improvements at higher functional levels.
- PODCI scores effectively estimate 6MWT performance and clinical meaningfulness in DMD.
Introduction:
Data is currently lacking anchoring a 30-meter longitudinal change in walking ability by 6-minute walk test (6MWT) in Duchenne muscular dystrophy as a minimal clinically important difference and "clinically meaningful" person-reported outcomes (PROs) at differing levels of ambulatory ability.
Methods:
We describe correlation between measures, 1-year change in measures, and correlation of 1-year changes between measures for the six-minute walk test (6MWT), 10-meter run/walk velocity, PedsQL and POSNA Pediatric Outcomes Data Collection Instrument (PODCI) in 24 4-12 year old. ambulatory DMD and 36 typical controls, and determine if minimal clinically important differences (MCID) of PROs contribute to different estimates of 6-minute walk distance (6MWD) change at differing levels of ability.
Results:
PedsQL total and physical function and PODCI global, transfer/mobility and sports/physical function PROs demonstrated significant differences between DMD and controls (p<0.00001). In DMD, 6MWD and 10-meter run/walk velocity were correlated with PODCI domain scores, with the transfer/mobility scale showing the strongest relationship (r=0.79 and r=0.76). In DMD, 6MWD distance and 10-meter run/walk velocity weakly correlated with PedsQL domain scores. In DMD, 6MWD, 10-meter run/walk velocity, and PODCI global and transfer and basic mobility demonstrated significant one-year change and exceeded the amount of change representing MCID. In DMD, 6MWD change highly correlated with change in PODCI global and PODCI transfer/mobility scores (r=0.76 and r=0.93). PODCI global and PODCI transfer/mobility scales provided the best estimates of 6MWT performance. A "meaningful" 4.5 point change in a low PODCI transfer / basic mobility score of 30 to 34.5 was associated with a 5.6m 6MWD change from 150.3 to 155.9m. At PODCI levels closer to normative levels for healthy controls, the change in 6MWD distance associated with a "meaningful" change in PODCI scores was almost 46m.
Discussion:
At lower levels of function, smaller increases in 6MWD result in meaningful change in quality of life (QoL) instrument scores. At higher levels of function, larger increases may be necessary to achieve the same QoL change score.
