Digital tech may help detect motor impairment in asymptomatic LOPD
Study: It could ID impairments not evident in standard clinical evaluation
Wearable digital health technologies (DHTs) may help identify subtle walking and movement impairments in people with late-onset Pompe disease (LOPD) that are not evident in standard clinical evaluation, a recent study in Italy shows.
These technologies “may have important implications for management, follow-up, and treatment decisions in clinical practice,” researchers wrote. “Importantly, our results suggest that DHT deserve to be evaluated as a promising outcome measure for clinical trials.”
The study, “Extensive digital health technology assessment detects subtle motor impairment in mild and asymptomatic Pompe disease,” was published in Scientific Reports.
Response to ERT treatment may vary for LOPD patients
Pompe disease is caused by mutations in the GAA gene that result in a missing or dysfunctional GAA enzyme, which is needed to break down a complex sugar molecule called glycogen. As a result, glycogen accumulates inside cells, particularly in muscle cells, leading to symptoms like muscle weakness and issues with eating, hearing, and breathing.
Enzyme replacement therapy (ERT), in which a lab-made version of the GAA enzyme is given to patients to replace the missing or nonfunctional enzyme, is standard practice for the treatment of Pompe disease. However, in people with LOPD, response to treatment may vary, and patients may eventually experience a clinical decline.
In this study, a team led by researchers in Italy used DHTs to assess subtle mobility impairment in people with LOPD. Eight patients were enrolled, including five with symptomatic and three with mild/asymptomatic disease. Their mean age was 43 years and five were male. A total of 52 age-matched healthy controls were also included.
Symptomatic participants showed motor impairment based on clinical scales and the six-minute walking test, a standard measure of exercise capacity. One of the mildly affected/asymptomatic participants was diagnosed due to mild fatigability, or susceptibility to becoming fatigued with activity, during adolescence. The other two were asymptomatic at diagnosis. Patients asymptomatic at diagnosis later started ERT due to MRI evidence of fatty substitution in muscle.
Study shows DHTs have capacity to detect motor impairments, researchers say
All participants underwent an extensive DHT mobility assessment of gait, turning, and postural transition to detect mobility difficulties. The researchers used the RehaGait system, which consists of three mobile sensors that were attached to the shoes and the spine.
Motor performance in daily life was assessed by tools such as the Timed Up and Go test, which evaluates the time it takes for a person to stand up from a chair, walk a short distance, turn around, walk back, and sit down again.
People with LOPD took a significantly lower number of steps (578 vs. 710), had a longer step time (0.67 vs. 0.51 seconds), higher step time variability (0.07 vs. 0.04), and a shorter step length (0.61 vs. 0.69 meters) compared with controls.
During the turning task, people with LOPD exhibited a lower angular velocity, or the rate at which a person rotates (79.8 vs.90.8 radians/s).
The LOPD group took significantly longer when transitioning from sitting to standing. During the Five Times sit-to-stand test (of standing and sitting five times], they had a lower maximum extension velocity when standing up (70.38 vs. 94.35 cm/s) and longer duration of the standing phases between transitions.
The small number of subjects remains the main limitation of this study, although we have demonstrated the validity of DHT assessment even with a limited sample size and high heterogeneity [variability] of motor involvement.
Mildly affected or asymptomatic patients exhibited a significantly higher step time variability (0.06 vs. 0.03 seconds) and lower step length (0.54 vs. 0.68). These alterations still showed normal scores on clinical scales and timed motor tests.
In the turning and sit-to-stand tasks, there was a trend toward reduced angular speed and longer task duration among people with mild or asymptomatic LOPD.
Overall, the study shows DHTs have the capacity to detect motor impairments in this patient population, facilitating more timely and personalized treatment decisions, according to the researchers.
“However, while digital metrics show significant promise, a critical next step will be establishing clinically meaningful thresholds that define when a detected digital change reflects true disease progression or necessitates clinical action,” the researchers noted. “The small number of subjects remains the main limitation of this study, although we have demonstrated the validity of DHT assessment even with a limited sample size and high heterogeneity [variability] of motor involvement.”
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