mActive: A Randomized Clinical Trial of an Automated mHealth Intervention for Physical Activity Promotion

Abstract

Background: We hypothesized that a fully automated mobile health (mHealth) intervention with tracking and texting components would increase physical activity.

Methods and results: mActive enrolled smartphone users aged 18 to 69 years at an ambulatory cardiology center in Baltimore, Maryland. We used sequential randomization to evaluate the intervention's 2 core components. After establishing baseline activity during a blinded run-in (week 1), in phase I (weeks 2 to 3), we randomized 2:1 to unblinded versus blinded tracking. Unblinding allowed continuous access to activity data through a smartphone interface. In phase II (weeks 4 to 5), we randomized unblinded participants 1:1 to smart texts versus no texts. Smart texts provided smartphone-delivered coaching 3 times/day aimed at individual encouragement and fostering feedback loops by a fully automated, physician-written, theory-based algorithm using real-time activity data and 16 personal factors with a 10 000 steps/day goal. Forty-eight outpatients (46% women, 21% nonwhite) enrolled with a mean±SD age of 58±8 years, body mass index of 31±6 kg/m(2), and baseline activity of 9670±4350 steps/day. Daily activity data capture was 97.4%. The phase I change in activity was nonsignificantly higher in unblinded participants versus blinded controls by 1024 daily steps (95% confidence interval [CI], -580 to 2628; P=0.21). In phase II, participants receiving texts increased their daily steps over those not receiving texts by 2534 (95% CI, 1318 to 3750; P<0.001) and over blinded controls by 3376 (95% CI, 1951 to 4801; P<0.001).

Conclusions: An automated tracking-texting intervention increased physical activity with, but not without, the texting component. These results support new mHealth tracking technologies as facilitators in need of behavior change drivers.

Clinical trial registration: URL: http://ClinicalTrials.gov/. Unique identifier: NCT01917812.

Keywords: accelerometer; activity tracker; automation; cardiovascular disease; digital health; eHealth; health technology; mHealth; mobile phone; pedometer; physical activity; prevention; smartphone; text messages; texting; wearable device; wearable sensor.

Figure 1

mActive trial flow diagram. IPAQ indicates International Physical Activity Questionnaire, Long‐Form.

Figure 2

Proportions attaining the 10 000 steps/day goal at baseline, in phase I, and phase II, by intervention group. Forty‐eight percent of participants attained the 10 000 step/day goal at baseline. No significant change or between‐group difference was observed in phase I, whereas in phase II, the unblinded‐texts group showed a 37% absolute increase and 84% relative increase over other groups in 10 000 steps/day attainment (P=0.02).