Motivational interviewing chatbot improves lifestyle in primary healthcare settings in a pragmatic randomised controlled trial.

Non-communicable diseases (NCDs) impose escalating demands on community-based primary healthcare (PHC) systems globally. Motivational interviewing (MI) is effective but difficult to scale due to resource and training constraints. We conducted the first pragmatic trial evaluating whether an automated chatbot operationalising MI principles could improve lifestyle behaviours when integrated into routine PHC settings. This pragmatic, open-label, multicentre randomised controlled trial across three Hong Kong PHC facilities randomised 627 adults aged 45-75 with or at risk of hypertension or diabetes. Participants received either a 12-week automated MI chatbot intervention plus usual care or usual care alone. Modified intention-to-treat analysis (n = 460) showed significant improvements in the intervention group compared to usual care in physical activity (576 MET-min/week), fruit/vegetable intake (0.27 portions/day), and committed action (0.95 a.u.) at 12 weeks. Larger effects among adherent participants suggested a dose-response relationship. Exploratory subgroup analyses showed strong effects among participants with low baseline physical activity (537 MET-min/week) and systolic blood pressure reductions among hypertensive participants (-5.03 mmHg). Effects were sustained at 9-month follow-up. No serious adverse events were reported. This scalable MI chatbot offers a pragmatic approach to NCD prevention in resource-constrained settings. Trial registration: ClinicalTrials.gov, NCT05949320, registered 29 June 2023.