JMIR Publications

ABSTRACT

Background:

Autonomic dysfunction is common post-concussion and may be compounded by inactivity. Accordingly, physical activity progression is an important component of concussion rehabilitation. Fitbit devices can provide objective longitudinal data on physical activity, physiologic response to activity, and sleep. However, participants must have adequate adherence to device wear to provide accurate data. The threshold for adequate adherence may change based on the research question, making it important to understand how adherence changes with different thresholds. Further, it is unclear how much staff support (i.e., reminders) may be required to maintain an adequate level of adherence.

Objective:

(1) Evaluate adherence to Fitbit device wear during daytime and nighttime using 3 different thresholds (50%, 75%, and 90% wear time) over 13 weeks in adolescents presenting for specialty concussion care and (2) report on the number of reminders required to achieve the observed level of adherence.

Methods:

Eighty adolescents were recruited from a specialty concussion clinic. Participants were asked to wear a Fitbit Sense 2 device day and night for 1 year. We analyzed data collected in the first 13 weeks. We used 3 different adherence thresholds: 50%, 75%, and 90%. For each threshold, a day or night was considered valid if the percentage of minutes with recorded heart rate data was greater than or equal to the defined threshold. We fit two robust linear mixed-effects models with number of valid days or valid nights as the outcome, a fixed effect for time (week), a fixed effect for threshold (50%, 75%, and 90%), a time by threshold interaction, and a random slope and intercept for participant. We also calculated the percentage of participants who required a reminder to wear and/or synchronize the device and the average number of reminders sent per participant across the study period.

Results:

Seventy participants were included in the analyses. We found that over 13 weeks, adolescents had average daily adherence ranging from 3.0-4.4 days/week (42%-63%) and nightly average adherence ranging from 3.6-3.9 nights/week (51%-56%). For all thresholds, adherence was highest during the first week. The number of valid wear days (β=-0.2, p<0.0001) and nights (β=-0.2, p<0.0001) decreased each week, regardless of the adherence threshold used. Fifty participants (71%) required at least 1 reminder. Overall, an average of 3.1 reminders were sent per participant across the study period.

Conclusions:

We found that adolescents presenting for specialty concussion care had adequate adherence to Fitbit device wear over 13 weeks. Approximately three quarters of the participants required at least 1 reminder from the study team to wear and/or synchronize their Fitbit device. This suggests that collecting longitudinal data with a Fitbit device is feasible in adolescents presenting for specialty concussion care but requires reminders to promote adherence.