JMIR Publications

ABSTRACT

Background:

Smartphone studies provide an opportunity to collect frequent data at low burden for people with neurodegenerative diseases such as amyloid lateral sclerosis (ALS). Yet due to the progressive decline of their cognitive and functional abilities, long-term adherence may not be feasible.

Objective:

To investigate adherence and data completeness in two observational cohort studies and one clinical trial in people with ALS.

Methods:

We estimated time-to-discontinuation, identified predictors of app discontinuation, and quantified data completeness for early drop-outs and participants who remained engaged longitudinally.

Results:

Kaplan-Meier estimates of time-to-discontinuation showed that after 3 months in the study, 59% to 96% of participants still contributed active data (surveys and audio recordings). For passively collected location data, this was 86% to 100%. Mean data completeness was highest for location data. Time-to-discontinuation was longest in the clinical trial and shortest in the year-long observational study. Our analysis did not provide evidence that demographic characteristics or disease severity at baseline are associated with attrition, although our analysis was underpowered to detect predictors of attrition. Data completeness fluctuated around 75% for participants that adhered long-term, whereas early dropouts had low data completeness for their first month(s) in the study. For most participants, data completeness declined over time: mean data completeness was typically lower in the last month in study.

Conclusions:

Participant engagement, as measured by time-to-discontinuation was higher than in published data. Our study provides an important benchmark for participant engagement with a smartphone app in neurodegenerative research. We showed that passive data completeness was higher than active data completeness and provide recommendations for identifying participants who are likely to adhere during the initial phase of a study. Frequent active and passive data collection from people with neurodegenerative diseases, specifically ALS, is feasible. In spite of patients' progressive physical and cognitive decline, time-to-discontinuation was higher than in typical smartphone studies. The observational studies, where no adherence reinforcement or incentives were implemented, provide an important benchmark for participant engagement with a smartphone app in neurodegenerative research. Our studies suggest that monitoring active data completeness during a screening period for a trial could help identify participants who are more likely to adhere ('run-in and withdrawal' design). Clinical Trial: The trial is registered at ClinicalTrials.gov (NCT03168711).