Accepted for/Published in: JMIR Research Protocols
Date Submitted: Apr 9, 2019
Date Accepted: Apr 6, 2020
Use of a Smartphone App to Increase Physical Activity Levels in Insufficiently Active Adults: A Feasibility Sequential Multiple Assignment Randomized Trial (SMART)
ABSTRACT
Background:
The SMART design allows for changes in the intervention during the randomized controlled trial period. Despite its potential and feasibility for defining the best sequence of interventions, so far it has never been utilized in a smartphone/gamified intervention for physical activity.
Objective:
To investigate the feasibility of a SMART design for assessing the effects of a smartphone app intervention to improve physical activity in adults. We also assessed qualitative features related to participants’ reaction regarding the goals established as well as comments from the participants.
Methods:
We conducted a feasibility 24-week/2-stage SMART [ReBEC #RBR-8xtc9c] in which 18 insufficiently active participants (< 10000 steps/day) were first randomized to Group 1 (smartphone app only), Group 2 (smartphone app + tailored messages) and a control group. Participants were motivated to increase at least 2000 steps/day on average each week. Based on the 12-week intermediate outcome, responders kept their interventions and non-responders were rerandomized to a subsequent treatment. In group 3 (Smartphone app + gamification), participants were instructed to form groups to use several game elements available in the chosen application (Pacer®). We fit linear regressions for each participant with the relationship between weeks and steps/day. We considered responders those with any positive slope at the end of the 1st stage intervention. We compared the accelerometer-based steps/day before and after the intervention as well as the slopes of the app-based steps/day between the 1st and second stages of treatment.
Results:
Twelve participants and five controls finished the intervention. We identified two responders in group 1. We did not observe significant changes in the steps/day neither throughout the intervention nor compared to the control group. However, the rerandomization of the five non-responders led to a change in the slope of the steps/day of a median, -198 steps/day (interquartile range, -279 to -103) to 20 steps/day (-204 to 145), P = .079. Finally, we observed in three participants in the group 2 an increase in the number of steps/day up to the sixth week followed by an inflection to baseline values or even lower (i.e., a quadratic relationship). The qualitative analysis showed that participants’ reports could be classified into three categories: (1) difficulty in managing the app and technology or problems with the device, (2) good response to the app, and (3) difficulties to achieve the goals.
Conclusions:
The SMART design was feasible and changed the behavior of the steps/day after rerandomization. Our results suggest that the rerandomization should be implemented earlier to take advantage of the tailored messages. Also, difficulties with technology and a realistic and individualized goal should be considered in interventions for physical activity using smartphones. Clinical Trial: ReBEC #RBR-8xtc9c
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