Short-distance walking speed test in Pompe disease is less demanding
Distance covered in 6 minutes correlated with walking speed over 10 meters
A test that measures walking speed over 10 meters (33 feet) offers a simpler and less demanding alternative to the commonly used six-minute walk test for evaluating walking performance in Pompe disease, and may be a better option for patients who have difficulty covering longer distances.
In a French study with adults and adolescents being treated with Sanofi‘s Myozyme (alglucosidase alfa) — marketed as Lumizyme in the U.S. — researchers found that the distance covered over six minutes, a test known as 6MWT, correlated well with walking speed in the 10-meter walk test.
“Its strong correlation with the 6MWT and ease of implementation support its integration into clinical practice and trials,” the researchers wrote in “A model to predict the 6-Minute Walk Distance in Pompe disease,” which was published in the Journal of Neuromuscular Diseases.
Pompe disease occurs due to a lack of an enzyme that breaks down glycogen into glucose, a simple sugar. Without the enzyme, glycogen builds up in cells, causing muscle weakness. People with Pompe often have difficulty walking, which can increase their risk of falling.
Monitoring changes in gait is important and “this is especially true for neuromuscular diseases, where premature fatiguability and progressive muscle weakness are hallmark features that influence both mobility and quality of life,” the researchers wrote.
A ‘less demanding alternative’
The 6MWT is often used to record the maximum distance a person can walk along a straight path. The total distance covered over six minutes is used to calculate walking speed. However, the test may be too demanding when motor impairment is severe.
Here, researchers investigated whether the 10-meter test may be better suited for adults and adolescents with Pompe disease. For the test, patients are instructed to walk as quickly as possible, without running, along a hallway marked for 12 meters. The time it takes to walk 10 meters is converted into walking speed.
The study included 74 patients (mean age, 54.4) who had 712 visits total over a mean period of 6.6 years. They walked at a mean speed of 1.1 meters (3.6 feet) per second in the 10-meter test. Over six minutes, they covered a mean of 300.6 meters (986 feet) at a speed of 0.8 meters (2.6 feet) per second.
Walking speed in both tests correlated well, meaning the 10-meter walk test — which patients completed within a mean of 13.3 seconds — can offer an alternative for the longer 6MWT.
The best prediction model included not only walking speed from the 10-meter test, but also age, sex, height, and weight. This model produced accurate results, closely predicting the results of a 6MWT. Adding other measures “offered only marginal improvements in accuracy,” wrote the researchers, who noted that by “providing accurate predictions,” this model may have “potential utility in clinical settings where the [6MWT] may be impractical due to patient fatigue or severe mobility limitations.”
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