A model to predict the 6-Minute Walk Distance in Pompe disease

Pompe disease is a rare neuromuscular disorder caused by acid alpha-glucosidase deficiency, leading to glycogen accumulation and progressive striated muscle weakness. The 6-minute walk test (6MWT) is commonly used to assess functional capacity in neuromuscular diseases but can be challenging for severely affected ambulant patients.

This study aimed to develop and validate predictive models for 6MWT performance using simpler, less demanding tests.

This retrospective monocentric study included 74 patients with Pompe disease (712 visits) and a mean follow-up of 6.6 ± 3.8 years. Functional assessments included the 6MWT, 10-meter walk test (10mWT) which was specifically used to determine gait speed, timed tests, strength and respiratory measures, and the Motor Function Measure (MFM-32). Linear regression models were developed to predict 6MWT speed, with validation using an 80%-20% training-testing split.

The cohort had an equal male-to-female ratio, with a mean age of 54.4 ± 13.5 years. The 10mWT speed showed a strong correlation with 6MWT speed (R = 0.91, p < 0.0001), confirming its potential as a surrogate measure. The most practical predictive model included 10mWT speed, age, sex, height, and weight, achieving an adjusted R² of 0.86. This model balances simplicity and accuracy, relying on easily measurable parameters suitable for routine clinical use. More complex models, including variables such as the MFM-32 or supine-to-sit time, offered only marginal improvements in accuracy.

The 10mWT offers a robust and less exhausting alternative to the 6MWT for assessing walking capacity in Pompe disease, particularly for ambulant patients with severe mobility limitations. Its strong correlation with the 6MWT and ease of implementation support its integration into clinical practice and trials.