Effectiveness of text messages for decreasing inactive behaviour in patients with knee osteoarthritis: a pilot randomised controlled study

Abstract Background One of the big contributors to physical inactivity in the elderly population is osteoarthritis (OA) of the knee. Digital motivation seems to have a positive effect on individual physical inactivity level, but limited evidence exists on the effects of digital motivation on patients with knee OA. Objective To investigate if motivational text messages reduce time spent physically inactive in patients with knee OA. Method This study was designed as an unblinded pilot randomised controlled trial, randomising participants equally (1:1) to an intervention group (motivational text messages) or control group (no intervention). Participants were recruited from six physical therapy clinics in Denmark. Inclusion criteria were age ≥ 18, diagnosed with knee OA, owner of a smartphone or tablet, and participating or commencing participation in the GLA:D® program. The primary outcome was time spent physically inactive, measured with a tri-axial accelerometer mounted on the lateral side of the thigh. Data on OA symptoms were obtained using the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Results A total of 49 participants were screened, and 38 participants were included and randomised to either the intervention group (n = 19) or the control group (n = 19). No statistically significant difference between the two groups was found in average change of time spent physically inactive (mean difference 13.2 min/day [95% CI − 41.0 to 67.3]; P = 0.63), time spent standing (mean difference 3.0 min/day [95% CI − 22.7 to 28.7]; P = 0.81), or time spent moving (mean difference − 20.4 min/day [95% CI − 63.0 to 22.3]; P = 0.34) nor was there any difference in change between the two groups on KOOS. Conclusion Motivational text messages have seemed to have no effect on overall time spent physically inactive. Trial registration clinicaltrials.gov, NCT03339011 . Registered 9 November 2017