Efficacy of Mobile Instant Messaging–Delivered Brief Motivational Interviewing for Parents to Promote Physical Activity in Pediatric Cancer Survivors: A Randomized Clinical Trial

IMPORTANCE: Physical activity has beneficial effects that mitigate cancer- and treatment-related late effects. However, children who survive cancer are often physically inactive. Brief motivational interviewing may be an effective approach for increasing children's physical activity levels. OBJECTIVE: To examine the effects of mobile instant messaging–delivered brief motivational interviewing for parents in promoting regular physical activity in children who have survived cancer. DESIGN, SETTING, AND PARTICIPANTS: An assessor-blinded randomized clinical trial was conducted at 2 Hong Kong pediatric oncology outpatient clinics from March 1, 2019, to January 29, 2021. A total of 161 children who had survived cancer, aged 9 to 16 years, and their parents were randomized (1:1) to an intervention or control group. INTERVENTIONS: The intervention group received a 6-month mobile instant messaging–delivered brief motivational interviewing using a strategy menu. Parent-child dyads in both groups received a health advice session and were directed to a physical activity website at baseline. MAIN OUTCOMES AND MEASURES: The primary outcome was the children’s physical activity levels at 12-month follow-up, measured by the Chinese University of Hong Kong: Physical Activity Rating for Children and Youth (total sores: 0-10, higher scores indicate greater physical activity levels). Secondary outcomes were cancer-related fatigue levels, handgrip strength, peak expiratory flow rate, and quality of life. Intention-to-treat analysis was performed. RESULTS: Of the 161 children included in the study, 93 were boys (57.8%), and the mean (SD) age was 12.4 (2.4) years. Generalized estimating equation analyses showed a significant improvement in outcomes in the intervention group compared with the control group: physical activity levels (group-by-time interaction, 6 months: β = 3.09; 95% CI, 2.65-3.53; P < .001; 12 months: β = 3.91; 95% CI, 3.45-4.36; P < .001), cancer-related fatigue (6 months: β = −5.69; 95% CI, −8.03 to −3.35; P < .001; 12 months: β = −9.16; 95% CI, −11.31 to −7.00; P < .001), left handgrip strength (6 months: β = 2.69; 95% CI, 0.96-4.43; P = .002; 12 months: β = 5.52; 95% CI, 3.70-7.33; P < .001), right handgrip strength (6 months: β = 2.75; 95% CI, 1.01-4.50; P = .002; 12 months: β = 5.45; 95% CI, 3.62-7.27; P < .001), peak expiratory flow rate (12 months: β = 28.51; 95% CI, 16.10-40.92; P < .001), and quality of life (6 months: β = 5.01; 95% CI, 1.19-8.82; P = .01); 12 months: β = 14.19; 95% CI, 10.84-17.54; P < .001). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, mobile instant messaging–delivered brief motivational interviewing was effective in promoting the adoption and maintenance of regular physical activity and ameliorating cancer- or treatment-related adverse effects in children who survived cancer. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03859271