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Published on: January 12, 2019
Minimal clinically important differences in six-minute walking distance in late-onset Pompe disease
Kristl G Claeys1,2, Hani Kushlaf3, Syed Raza4
1Department of Neurology, University Hospitals Leuven, Leuven, Belgium.
Background:
The minimal clinically important difference (MCID) is the smallest change in outcome that physicians or patients would consider meaningful and is relevant when evaluating disease progression or the efficacy of interventions. Studies of patients with late-onset Pompe disease (LOPD) have used the 6-min walk distance (6MWD) as an endpoint to assess motor function. However, an MCID for 6MWD (% predicted and meters) has yet to be established in LOPD. The objective of the study was to derive 6MWD MCID (% predicted and meters) with different analysis methods and for subgroups of different disease severity for LOPD.
Methods:
Data from the PROPEL trial were used to calculate 6MWD MCID in the overall PROPEL population and subgroups of baseline severity as assessed by walking distance and body mass index (BMI), using anchor- and distribution-based approaches.
Results:
The 6MWD MCIDs varied widely, depending on the method and subgroup, ranging from 2.27%-8.11% predicted for the overall LOPD population (23.7 m-57.2 m). For patients with baseline 6MWD < 150 m, MCIDs ranged from -0.74%-3.37% (-2.1 m-11.3 m). MCIDs increased with distance walked at baseline until a plateau was reached. For BMI subgroups, the MCIDs were generally lowest in obese patients.
Conclusion:
Our analysis shows that MCID depends on the chosen method and disease severity. The findings suggest that applying a single MCID to all patients can be misleading; consequently, a range of possible MCIDs should be considered. This may also be highly relevant for other neuromuscular diseases. This study provides a range of 6MWD MCIDs for LOPD, with lower MCIDs for more severe patients.
Insights
Establishing the minimal clinically important difference (MCID) for the 6-min walk distance (6MWD) in late-onset Pompe disease (LOPD) is crucial. This study found that MCID varies by method and disease severity, suggesting a range should be used for LOPD patients.
Area of Science:
- Neurology
- Clinical Trials
- Biostatistics
Background:
- The minimal clinically important difference (MCID) quantifies meaningful outcome changes in disease progression and intervention efficacy.
- The 6-minute walk distance (6MWD) is a key motor function endpoint in late-onset Pompe disease (LOPD).
- An established MCID for 6MWD in LOPD is currently lacking.
Purpose of the Study:
- To derive the MCID for 6MWD (in % predicted and meters) in LOPD.
- To analyze MCID using various methods and for subgroups based on disease severity.
- To provide a basis for interpreting 6MWD changes in LOPD clinical trials and practice.
Main Methods:
- Utilized data from the PROPEL trial for MCID calculations.
- Employed both anchor- and distribution-based approaches.
- Analyzed overall LOPD population and subgroups stratified by baseline walking distance and BMI.
Main Results:
- 6MWD MCIDs varied significantly by method and subgroup, ranging from 2.27%-8.11% predicted (23.7 m-57.2 m) in the overall population.
- For patients with baseline 6MWD < 150 m, MCIDs ranged from -0.74%-3.37% (-2.1 m-11.3 m).
- MCIDs demonstrated a trend of increasing with baseline walking distance up to a plateau, and were lowest in obese patients.
Conclusions:
- MCID for 6MWD in LOPD is dependent on the analytical method and patient's disease severity.
- A single MCID value may be misleading; a range of MCIDs should be considered.
- Findings are relevant for other neuromuscular diseases and highlight the need for severity-specific interpretation of 6MWD in LOPD.
