Smartphone Monitoring Feasible for Quantifying Mobility of Patients with ALS
Key findings
- Sensors inside a smartphone allow its location to be tracked, and Massachusetts General Hospital researchers have been studying whether smartphones are useful for studying and quantifying the behavior of patients with amyotrophic lateral sclerosis (ALS)
- To investigate whether smartphone data could identify mobility changes related to COVID-19 in people with ALS, the researchers compared pre-pandemic data (February 13 to March 12, 2020) with pandemic-phase data (March 13 to April 13, 2020) for eight participants
- People with ALS spend more time at home and travel less than the general population at baseline. With the pandemic, median time at home increased and distance traveled decreased significantly
- A participant with low function stayed at home more and traveled less than a participant with highest functional ability, both before and after the pandemic was declared
- Thus, smartphone-based "digital phenotyping" can quantify the mobility of patients with ALS. This might allow smartphone data to act as an important outcome measure for ALS treatment trials
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Smartphones are being used increasingly often in medical research to gather passive information about people's behavior. For example, sensors inside a smartphone allow its location to be tracked, and Massachusetts General Hospital researchers have been using that data to study the mobility of people with amyotrophic lateral sclerosis (ALS).
When the COVID-19 pandemic began, the researchers decided to investigate whether smartphone data could identify mobility changes related to the pandemic. In Muscle & Nerve, Anna L. Beukenhorst, PhD, postdoctoral research fellow, Ella Collins, researcher, Jukka-Pekka Onnela, PhD, director of the Master of Science in Health Data Science Program in the Harvard T.H. Chan School of Public Health, James D. Berry, MD, MPH, director of the Neurological Clinical Research Institute at Mass General, and colleagues document decreased mobility of people with ALS after stay-at-home orders and other restrictions were put into place.
Study Methods
At Mass General and Washington University in St. Louis, the researchers recruited eight patients with ALS who provided informed consent. Participants installed an app on their personal smartphones that collected location data for 60 seconds every 10 minutes. For this analysis, the researchers compared pre-pandemic data (February 13 to March 12, 2020) with pandemic-phase data (March 13 to April 13, 2020).
Overall Results
An interrupted time series showed:
Median time at home:
- Pre-pandemic—19 hours
- During pandemic—24 hours
Median distance traveled daily:
- Pre-pandemic—24 km
- During pandemic—4 km
A mixed-effects model confirmed that the U.S. government's declaration of a state of emergency on March 13 substantially affected both outcomes:
- Home time: +5 hours; 95% CI, +0.75 to +9.7
- Distance traveled: −48 km; 95% CI, −77 to −19
Thus, people with ALS may be relatively protected from COVID-19, but they and other people with neurologic disorders may also be experiencing increased social isolation.
Results According to Function
The researchers compared the mobility of an ambulatory participant who had near-normal pre-pandemic function (score on the Revised ALS Functional Rating Scale [ALSFRS-R], 46/48) and a non-ambulatory participant with low function (ALSFRS-R score, 23/48).
Ambulatory participant:
- Median home time—18 hours pre-pandemic, 21 hours during pandemic
- Median distance traveled—68 km pre-pandemic, 30 km during pandemic
Non-ambulatory participant:
- Median home time—23 hours pre-pandemic, 24 hours during pandemic
- Median distance traveled—2.2 km pre-pandemic, 2.1 km during pandemic
Although this sample is small, the findings support the use of the ALSFRS-R and smartphone-based "digital phenotyping" to quantify the impact of ALS on people's lives. Furthermore, digital phenotyping could be a simple and useful outcome measure to quantify the benefit of novel ALS therapies in treatment trials.
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