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

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 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40814-019-0494-6) contains supplementary material, which is available to authorized users.