Feasibility of the “LvL UP” trial: a pilot sequential multiple assignment randomised trial of an adaptive, holistic mHealth lifestyle coaching intervention

Background Mobile Health (mHealth) interventions are promising for addressing the growing burden of noncommunicable diseases and common mental disorders but often focus on single domains and lack adaptability. LvL UP (“Level Up”) is a holistic mHealth lifestyle coaching intervention that integrates physical activity, diet, and emotional regulation. It provides blended coaching support through an app-based conversational agent with adaptive human support. This pilot trial assessed the feasibility of delivering the LvL UP intervention and implementing its adaptive procedures using a sequential multiple assignment randomised trial (SMART) design. Methods This eight-week pilot trial was conducted from 29 March to 1 August 2024. We recruited adults in Singapore aged 21–59 at risk of chronic conditions. Participants were randomised 2:1 to the intervention (LvL UP app with a peer supporter–LvL UP Buddy) or comparison (control app with educational resources). After four weeks, non-responders (defined as completing < 6 digital coaching sessions or rated session usefulness < 4/5) were re-randomised 1:1 to continue or receive three additional motivational interviewing (MI)-informed sessions with a human coach; responders remained on their original allocation. Primary outcomes included feasibility indicators: recruitment, LvL UP Buddy enrolment, non-responder rate, trial retention, data completion rate, and intervention engagement. Secondary outcomes measured changes from baseline to eight weeks in mental well-being, psychological distress, physical activity, sleep duration, and fruit and vegetable intake. Six progression criteria were prespecified to guide advancement to a definitive trial. Results Of the 458 individuals screened, 394 were eligible, and 123 were enrolled (82 interventions; 41 controls). Most intervention participants (95.1%) were paired with a LvL UP Buddy. Thirty-eight participants (46.3%) were non-responders; of those assigned to MI-informed sessions, 52.6% (10/19) completed all three. Eight-week retention was high (91.5% intervention; 92.7% control), with 12.2% missing data. Positive trends were observed in mental well-being (2.12, 95% CI [-0.58, 4.82]), psychological distress (-0.94 [-2.08, 0.20]), and sleep duration (0.49 h/week [0.17, 0.82]). The study met five of six prespecified progression criteria: recruiting ≥ 60 participants within six weeks, achieving ≥ 75% retention, maintaining ≤ 20% missing data, obtaining a 40–60% non-responder rate, and showing a positive change in ≥ 1 health-related outcome. The digital coaching session adherence fell below the target (39.5% vs. 70%). Conclusions LvL UP was feasible to deliver and evaluate using a SMART design. The results provide strong operational guidance and a solid foundation for the refinement and implementation of a fully powered trial. Trial registration ClinicalTrials.gov, TRN: NCT06360029, Registration date: 7 April 2024.