Smartphone tool able to capture daily SMA motor function changes
A novel smartphone sensor-based assessment tool is able to capture day-to-day changes in motor function in people with spinal muscular atrophy (SMA), according to a proof-of-concept study.
The digital tasks are engaging and easy to complete for most SMA patients, and the results are reliable, matching those from established clinical tests, data show.
As such, the study “supports the feasibility, reliability, and validity of using smartphone-based digital assessments to measure function in people living with SMA,” researchers wrote.
The study, “Digital measures of respiratory and upper limb function in spinal muscular atrophy: design, feasibility, reliability, and preliminary validity of a smartphone sensor-based assessment suite,” was published in the journal Neuromuscular Disorders.
Clinical tests monitor motor function changes every 3-6 months
SMA is a progressive disease, meaning its characteristic muscle weakness and wasting worsens over time. In the clinical, motor function changes are monitored using various assessments, including the 32-item Motor Function Measure (MFM-32).
Because visits to the clinic occur every 3-6 months, changes in disease severity between visits may not be fully captured.
Smartphones offer a way to monitor disease severity and progression on a daily basis in a home environment. Sensors within digital devices can actively and passively collect a range of data about specific outcome measures. Still, no existing digital monitoring tools have been assessed in SMA patients.
Scientists at Roche in Switzerland have now designed a smartphone sensor-based tool to monitor SMA symptoms and overall disease severity. The suite involves nine short tasks with a “friendly monster” theme for people with SMA, ages 6-60, to assess aspects of upper limb and lung function.
Tasks included Cheer the Monster, Turn the Phone, Walk the Rope, Collect the Coins, Squeeze the Tomato, Walk the Trails, Tap the Monster, Ring the Bell, and Carry the Egg. Each task was compared to specific items on standard SMA assessments, such as the MFM-32, the Revised Upper Limb Module (RULM), and forced vital capacity (FVC), a measure of lung function.
The digital biomarkers assessment presented here is proof of concept that motor and respiratory function in SMA can be measured remotely and reliably using smartphones.
Study recruited SMA patients from Phase 2 JEWELFISH trial
To test the clinical validity of the smartphone tool, researchers recruited a group of SMA patients who participated in the Phase 2 JEWELFISH trial (NCT03032172). This study is evaluating Roche’s Evrysdi (risdiplam) in 174 SMA patients who previously received other treatments.
Smartphone data from the first six weeks of the trial were provided by 116 JEWELFISH participants, with a mean age of 17.3 years, of whom 69% were diagnosed with SMA type 2. Eight of the nine tasks showed good or excellent test-retest reliability.
Participants completed the tasks over a median of 6.3 days per week, with a mean daily engagement time of about three minutes. Because too few participants were able to perform the Carry the Egg task for the minimal time required to obtain useful data, this task was excluded from the analysis.
In seven of the remaining eight tasks, the selected feature was significantly associated with its related in-clinic measure of motor function. Tasks that demonstrated the strongest correlation with MFM-32 items were Turn the Phone, which measures the maximum speed of turning the phone; Collect the Coins, mean time to collect a coin; and Squeeze the Tomato, the number of successful pinches.
Likewise, seven of the eight tasks measured by the smartphone’s sensors demonstrated significant association with total disease severity, as assessed with MFM-32 total scores. Significantly linked with MFM-32 total scores were Tap the Monster, the reaction time to tap the monster; Ring the Bell, maximum pressure; Collect the Coins; and Turn the Phone. Seven tasks were also associated with total RULM scores.
Weaker but statistically significant relationships were observed between the total voicing duration feature with the Cheer the Monster task and FVC and MFM-32 total scores. The Walk the Rope task, or the relative turning magnitude, was not associated with clinical assessments.
Using the Spinal Muscular Atrophy Independence Scale-Upper Limb Module (SMAIS-ULM) total score, a patient-reported assessment of independence, six of the eight tasks reached a significant association.
The strongest association with SMAIS-ULM total scores included Squeeze the Tomato and Collect the Coins. Showing significant but weaker relationships with SMAIS-ULM scores were Walk the Trails, the speed and accuracy of tracing a shape; Turn the Phone; Ring the Bell; and Tap the Monster. Cheer the Monster and Walk the Rope tasks were not associated with patient-reported independence scores.
“The digital biomarkers assessment presented here is proof of concept that motor and respiratory function in SMA can be measured remotely and reliably using smartphones,” the researchers wrote.
“A further analysis of longitudinal [over time] data from the JEWELFISH study and data on the use of our assessment suite from other independent studies will be important to demonstrate that the features are sensitive enough to changing severity over the course of the disease,” the team noted.
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