Effects of a novel mobile health intervention compared to a multi-component behaviour changing program on body mass index, physical capacities and stress parameters in adolescents with obesity: a randomized controlled trial

Abstract

Background: Less than 2% of overweight children and adolescents in Switzerland can participate in multi-component behaviour changing interventions (BCI), due to costs and lack of time. Stress often hinders positive health outcomes in youth with obesity. Digital health interventions, with fewer on-site visits, promise health care access in remote regions; however, evidence for their effectiveness is scarce.

Methods: This randomized controlled not blinded trial (1:1) was conducted in a childhood obesity center in Switzerland. Forty-one youth aged 10-18 years with body mass index (BMI) > P.90 with risk factors or co-morbidities or BMI > P.97 were recruited. During 5.5 months, the PathMate2 group (PM) received daily conversational agent counselling via mobile app, combined with standardized counselling (4 on-site visits). Controls (CON) participated in a BCI (7 on-site visits). We compared the outcomes of both groups after 5.5 (T1) and 12 (T2) months. Primary outcome was reduction in BMI-SDS (BMI standard deviation score: BMI adjusted for age and sex). Secondary outcomes were changes in body fat and muscle mass (bioelectrical impedance analysis), waist-to-height ratio, physical capacities (modified Dordel-Koch-Test), blood pressure and pulse. Additionally, we hypothesized that less stressed children would lose more weight. Thus, children performed biofeedback relaxation exercises while stress parameters (plasma cortisol, stress questionnaires) were evaluated.

Results: At intervention start median BMI-SDS of all patients (18 PM, 13 CON) was 2.61 (obesity > + 2SD). BMI-SDS decreased significantly in CON at T1, but not at T2, and did not decrease in PM during the study. Muscle mass, strength and agility improved significantly in both groups at T2; only PM reduced significantly their body fat at T1 and T2. Average daily PM app usage rate was 71.5%. Cortisol serum levels decreased significantly after biofeedback but with no association between stress parameters and BMI-SDS. No side effects were observed.

Conclusions: Equally to BCI, PathMate2 intervention resulted in significant and lasting improvements of physical capacities and body composition, but not in sustained BMI-SDS decrease. This youth-appealing mobile health intervention provides an interesting approach for youth with obesity who have limited access to health care. Biofeedback reduces acute stress and could be an innovative adjunct to usual care.

Keywords: Adolescents; Biofeedback; Conversational agent; Digital health interventions; Fitness; Obesity; Stress.

Fig. 1

Screenshots of the PathMate2 app. Legend Fig. 1: Side menu with the dashboard (indicating the progress, the percentage of challenges completed, and the number of gamified keys that were provided for each successful challenge), chat channels for the therapeutic PathMate2 team (human coaches) and the conversational agent Anna (left screenshot), chat interaction with Anna and pre-defined answer options (middle screenshot), and chat interaction with the human coach Björn (right screenshot)

Fig. 2

Participants flow throughout the study. Legend Fig. 2: Refer to patient characteristics for further information. PM: PathMate group, CON: Control group, T0: intervention start, T1 and T2: 5.5 and 12 months after intervention start, respectively, n: number of patients

Fig. 3

Group comparison of BMI-SDS at the start of intervention (T0), after 5.5 (T1) and 12 months (T2), and changes from T0 to T1 (= D1) and from T0 to T2 (= D2). Legend Fig. 3: ^* p-values < 0.05 for changes within groups. BMI-SDS: body mass index standard deviation score, PM: PathMate2 group, CON: Control group. The numbers above or below the boxplots indicate the number of patients investigated at each point of time

Fig. 4

Group comparison of body measurements at the start of intervention (T0), after 5.5 (T1) and 12 months (T2), and changes from T0 to T1 (= D1) and from T0 to T2 (= D2). Legend Fig. 4: ^* p-values < 0.05 for changes within groups. PM: PathMate2 group, CON: Control group. The numbers above or below the boxplots indicate the number of patients investigated at each point of time

Fig. 5

Group comparison of fitness test at the start of intervention (T0), after 5.5 (T1) and 12 months (T2), and changes from T0 to T1 (= D1) and from T0 to T2 (= D2). Legend Fig. 5: ^* p-values < 0.05 for changes within groups. PM: PathMate2 group, CON: Control group. The numbers above or below the boxplots in Fig. 5a indicate the number of patients investigated at each point of time and can be applied to all fitness tests

Fig. 6

Group comparison of blood pressure (BP) and pulse at the start of intervention (T0), after 5.5 (T1) and 12 months (T2), and changes from T0 to T1 (= D1) and from T0 to T2 (= D2). Legend Fig. 6: ^* p-values < 0.05 for changes within groups. PM: PathMate2 group, CON: Control group. The numbers above or below the boxplots indicate the number of patients investigated at each point of time

Fig. 7

Group comparison of stress parameters at baseline (Bl), after 5.5 (T1) and 12 months (T2), and changes from Bl to T1 (= D1) and from Bl to T2 (= D2). Legend Fig. 7: ^* p-values < 0.05 for changes within groups. ^# p-values < 0.05 for % change after relaxation within groups (whether % change after relaxation differs from 0). Baseline: on average 5 weeks before the start of intervention. Cortisol before relaxation (nmol/L): plasma cortisol before biofeedback relaxation exercise. Cortisol after relaxation (% change): percentage change of plasma cortisol after biofeedback relaxation exercise compared to cortisol before relaxation. BI: baseline, PM: PathMate2 group, CON: Control group, TICS: Trierer Stress Inventar questionnaire. The numbers above or below the boxplots indicate the number of patients investigated at each point of time