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Effective, resource-efficient treatment is urgently needed to address the high rates of pediatric and adolescent obesity. This need has been accelerated by the COVID-19 pandemic. The use of a mobile health tool as an early intervention before a clinic-based multidisciplinary weight management program could be an effective treatment strategy that is appropriate during a pandemic.
This study aims to assess the effectiveness of and adolescent engagement with a mobile app–based lifestyle intervention program as an early intervention before enrollment in a clinic-based multidisciplinary weight management program.
This prospective single-cohort study involved adolescents, aged 10-16 years, who were overweight and obese (defined as BMI percentile above the 85th percentile). Participants used the mobile Kurbo app as an early intervention before enrolling in a clinic-based multidisciplinary weight management program. Kurbo’s health coaches provided weekly individual coaching informed by a model of supportive accountability via video chat, and participants self-monitored their health behavior. The implementation of Kurbo as an early intervention was evaluated using the reach, effectiveness, adoption, implementation, and maintenance framework by reach (number who consented to participate out of all patients approached), implementation (Kurbo engagement and evaluation), and effectiveness as measured by the primary outcome of the BMI z-score at 3 months. Secondary outcome measures included changes in body fat percentage, nutrition and physical activity levels, and quality of life at 3 months. Maintenance was defined as the outcome measures at 6-month follow-up.
Of the 73 adolescents who were approached for enrollment, 40 (55%) of adolescents were recruited. The mean age was 13.8 (SD 1.7) years, and the mean BMI z-score was 2.07 (SD 0.30). In the multiethnic Asian sample, 83% (33/40) of the participants had household incomes below the national median. Kurbo engagement was high, with 83% (33/40) of participants completing at least 7 coaching sessions. In total, 78% (18/23) of participants rated the app as good to excellent and 70% (16/23) stated that they would recommend it to others. There were no statistically significant changes in BMI z-scores at 3 months (
The use of Kurbo before enrollment in an outpatient multidisciplinary clinical care intervention is a feasible strategy to expand the reach of adolescent obesity management services to a low-income and racially diverse population. Although there was no significant change in BMI z-scores, the use of Kurbo as an early intervention could help to improve quality of life and reduce body fat percentage and total caloric intake.
Mirroring global trends, the prevalence of overweight among Singaporean adolescents increased from 2.2% in 1975 to 15.9% in 2016. Overweight adolescents are at a higher risk for adult obesity as well as short- and long-term medical and psychosocial complications [
The commercially available mHealth weight management program, Kurbo, has provided individualized health coaching, educational videos on nutrition and physical activity, and self-monitoring to improve diet and physical activity behaviors [
Therefore, the primary objective of this study is to examine the implementation of Kurbo as an early intervention for adolescents with obesity before enrollment in a clinic-based multidisciplinary weight management program in Singapore. The evaluation used the relevant dimensions of the reach, effectiveness, adoption, implementation, and maintenance evaluation framework [
This was a prospective, single-arm study that conducted evaluations at three time points: baseline, 3 months, and 6 months. A total of 40 participants, with informed parental consent and child assent, were enrolled in the study at the point of referral to the KK Women’s and Children’s Hospital (KKH) weight management clinic (WMC). Participants were enrolled between October 2018 and March 2019. All study procedures were approved by the Singhealth Centralized Institutional Review Board. The study was registered at ClinicalTrials.gov (NCT03561597).
KKH is an 830-bed tertiary pediatric teaching hospital that provides two-third of the government-subsidized pediatric care in Singapore. The adolescent WMC is a physician-led multidisciplinary clinic where adolescents with overweight and their families engage with a multidisciplinary care team consisting of physicians, dietitians, exercise physiologists, and psychologists to set and monitor behavioral goals to manage obesity-related comorbidities. The KKH WMC protocols and outcomes have been previously published, with a historical dropout rate of 58% [
The usual waiting time for a first visit to the WMC clinic varies from 4 to 8 weeks after the initial referral. For this study, WMC providers had access to information about participants’ Kurbo progress through an administrator site during this period. This allowed for monitoring safety concerns and guiding discussions during clinic visits. After the first WMC visit, dietary recommendations and counseling were provided by the dietitian according to the recommended nutritional guidelines. Physical activity counseling was also performed by exercise trainers based on the World Health Organization guidelines on physical activity and sedentary behavior.
Adolescents, referred to the WMC, aged 10-17 years with a BMI percentile above the 85th percentile [
Kurbo is a mobile app developed to aid adolescents and their families with weight management through dietary self-monitoring and weekly coaching sessions (
Screenshot of Kurbo app.
Demographic and parental characteristics were obtained at the baseline. Questionnaires and food diaries were obtained through self-reports using physical forms during the study visits.
The implementation of the Kurbo program as an early intervention was evaluated using the relevant dimensions of reach, effectiveness, adoption, implementation, and maintenance framework [
Height, weight, waist circumference [
Adolescents’ daily total caloric intake and fruit and vegetable consumption were assessed using a 3-day food diary that has been previously validated for use with Singaporean adolescents [
Physical activity was assessed using a wGT3X+ ActiGraph accelerometer. Participants wore the accelerometer for a 7-day period at baseline, 3 months, and 6 months. The ActiGraph data were processed using ActiLife 6 software. The Puyau cutoff point of 3200 counts per minute was used to estimate the time spent in MVPA. When 20 minutes of consecutive zeros were present in the accelerometry data, it was assumed that the monitor was not being worn at that time. All days with >500 minutes of valid data were included in the analysis [
Self-reported questionnaires were administered to adolescents at baseline, 3 months, and 6 months. The Pediatric Quality of Life Inventory (PedsQoL; UK version 4) was administered to evaluate physical, emotional, school, and social functioning. The Eating Pattern Inventory for Children (EPI-C) [
Data were analyzed using SPSS version 9.3 for Windows (IBM Corp). BMI was computed as kg/m2, and the BMI z-score was calculated using the L, M, and S parameters published by the Centers for Disease Control and Prevention [
Of the 73 eligible participants, 40 (55%) were consented and enrolled in the study. The mean age of the participants was 13.8 (SD 1.7) years. Among this, 58% (23/40) of the enrolled adolescents were male, 45% (18/40) were Chinese, 33% (13/40) were Malay, and 13% (5/40) were Indian. Of 40 participants, 32 (80%) were referred to WMC as a result of opportunistic screening during medical visits for nonobesity-related conditions and 8 (20%) were referred specifically for obesity-related comorbidities. Moreover, 65% (26/40) of participants had a family history of metabolic diseases, and 83% (33/40) of accompanying parents were overweight or obese. Overall, 83% (33/40) of participants had household income less than the national median monthly household income of SGD 9500 (US $7125) [
Baseline characteristics of participants in the study (N=40).
Characteristics | Total (N=40) | Completers (n=20) | Drop-outs (n=20) | ||||||||
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Gender (male), n (%) | 23 (58) | 12 (60) | 11 (55) | .79 | ||||||
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.25 | |||||||||
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Chinese | 18 (45) | 12 (60) | 6 (30) |
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Malay | 13 (33) | 3 (15) | 11 (55) |
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Indian | 5 (13) | 2 (10) | 3 (15) |
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Other | 4 (10) | 4 (35) | 0 (0) |
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.32 | |||||||||
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Overweight | 8 (20) | 5 (25) | 3 (15) |
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Obesity | 32 (80) | 15 (75) | 17 (85) |
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Family history of metabolic diseases, n (%) | 26 (65) | 12 (60) | 14 (74) | .37 | ||||||
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Age (years), mean (SD) | 13.8 (1.7) | 14.6 (1.5) | 13.4 (1.8) | .62 | ||||||
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Body mass (kg), mean (SD) | 81.2 (17.2) | 83.8 (19.1) | 78.6 (15.1) | .34 | ||||||
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Height (cm), mean (SD) | 161.9 (11.4) | 163.3 (12.2) | 160.4 (10.7) | .43 | ||||||
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BMI (kg/m2), mean (SD) | 30.7 (3.9) | 30.6 (4.3) | 30.3 (3.5) | .79 | ||||||
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BMI z-scores, mean (SD) | 2.07 (0.30) | 2.05 (0.34) | 2.09 (0.25) | .68 | ||||||
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Waist-to-height ratio, mean (SD) | 0.61 (0.06) | 0.60 (0.06) | 0.61 (0.05) | .80 | ||||||
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Body fat percentage (%), mean (SD) | 43.3 (5.9) | 42.8 (5.8) | 44 (6) | .53 | ||||||
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Systolic | 121 (13) | 120 (13) | 117 (10) | .26 | |||||
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Diastolic | 69 (9) | 68 (10) | 67 (5) | .60 | |||||
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Age (years), mean (SD) | 43.6 (5.3) | 44.7 (5.2) | 42.5 (5.2) | .19 | ||||||
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Gender (female), n (%) | 33 (82) | 17 (85) | 16 (80) | .68 | ||||||
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Overweight | 11 (28) | 7 (35) | 4 (20) | .57 | |||||
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Obesity | 22 (55) | 10 (50) | 12 (60) | .57 | |||||
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.79 | |||||||||
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Married parent | 33 (82) | 17 (85) | 16 (80) |
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Single parent | 7 (18) | 3 (15) | 4 (20) |
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.11 | |||||||||
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Secondary school (equivalent to 10 years of education) | 21 (53) | 8 (40) | 13 (65) |
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Diploma | 11 (27) | 8 (40) | 3 (15) |
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Bachelor’s degree and above | 8 (20) | 4 (20) | 4 (20) |
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.27 | |||||||||
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Below 1500 (1125) | 13 (33) | 4 (20) | 9 (45) |
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1500-4499 (1125-3374.25) | 12 (31) | 9 (45) | 3 (15) |
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4500-7500 (3375-5625) | 11 (26) | 6 (30) | 5 (25) |
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Not reported | 4 (10) | 1 (5) | 3 (15) |
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CONSORT (Consolidated Standards of Reporting Trials) diagram showing the flow of participants through each stage of the trial. WMC: weight management clinic.
Overall, 83% (33/40) of participants completed at least 1 health coaching session. Participants completed a median of 7 (IQR 2-10) weekly sessions. Initial participant engagement across all Kurbo components was initially high but decreased over time (
A total of 23 participants completed the evaluation of Kurbo and individual components, as shown in
Number of participants who logged in at least one weight, food, or physical activity by week.
User-friendliness of the various components of Kurbo where 1=very difficult and 5=very easy.
Usefulness of the various component of Kurbo where 1=not useful and 5=very useful.
There were no significant changes in BMI z-score (primary outcome) at either 3 or 6 months. However, there was a significant reduction in body fat percentage at both 3 months (−1.3%; 95% CI −2.5% to −0.2%;
Changes in adolescents’ anthropometric and blood pressure (N=40).
Variable | Baseline to 3 months (n=21) | Baseline to 6 months (n=20) | ||
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Value, mean (SD; 95% CI) | Value, mean (SD; 95% CI) | ||
Body mass (kg) | 2.7 (4.74; 0.5 to 4.8) | .02 | 3.59 (4.55; 1.45 to 5.71) | .002 |
BMI z-score | 0.045 (0.15; −0.024 to 0.114) | .19 | 0.035 (0.14; −0.028 to 0.098) | .27 |
Waist circumference (cm) | 1.1 (6.74; −1.9 to 4.2) | .45 | 0.3 (6.21; −2.6 to 3.2) | .84 |
Waist-to-height ratio | −0.003 (0.040; −0.20 to 0.015) | .75 | 0.004 (0.038; −0.014 to 0.022) | .67 |
Body fat (%) | −1.31 (2.54; −2.47 to −0.15) | .03 | −2.0 (3.46; −3.6 to −0.38) | .02 |
Systolic BPa (mm Hg) | −5.5 (9.21; −9.8 to −1.2) | .02 | −2.1 (9.62; −6.8 to 2.5) | .35 |
Diastolic BP (mm Hg) | −4.2 (8.50; −8.1 to −0.2) | .04 | −3.2 (8.47; −7.3 to 0.85) | .11 |
aBP: blood pressure.
The 3-day food diary revealed significant reductions in caloric intake at 3 months (mean −300, SD 456; 95% CI −576 to −24;
Changes in adolescents’ health behavior and psychosocial parameters (N=40).
Variable | Baseline to 3 months (n=21) | Baseline to 6 months (n=20) | |||||||
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Value, mean (SD; 95% CI) | Value, mean (SD; 95% CI) | |||||||
Total (kcal/day) | −300 (457; −576 to −24) | .04 | −332 (518; −598 to −66) | .02 | |||||
Servings of vegetables per day | −0.17 (0.50; −0.5 to 0.1) | .24 | −0.0 (0.79; −0.4 to 0.4) | .99 | |||||
Average moderate-to-vigorous physical activity per day (minutes) | 1.47 (10.03; −4.3 to 7.2) | .59 | 5.3 (4.78; 0.88 to 9.75) | .03 | |||||
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Total | 2.4 (13.11; −3.1 to 7.9) | .38 | 1.4 (11.67; −4.2 to 7.0) | .61 | ||||
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Physical | 4.0 (13.56; −1.7 to 9.8) | .16 | 1.0 (11.60; −4.6 to 6.6) | .72 | ||||
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Emotional | 6.5 (23.34; −3.4 to 16.3) | .19 | 9.7 (20.58; −0.2 to 19.7) | .05 | ||||
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School | 8.3 (18.28; 0.6 to 16.1) | .04 | 6.9 (13.52; 0.2 to 13.7) | .04 | ||||
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Psychosocial | 6.3 (14.52; 0.2 to 12.5) | .04 | 6.5 (12.98; 0.2 to 12.7) | .04 | ||||
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Dietary restraint | 0.033 (0.42; −0.15 to 0.21) | .72 | 0.00 (0.48; 0.23 to −0.23) | .99 | ||||
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External eating | −0.087 (0.82; −0.44 to 0.27) | .62 | −0.19 (0.65; −0.50 to 0.12) | .22 | ||||
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Parental pressure to eat | 0.116 (0.54; −0.12 to 0.35) | .31 | 0.018 (0.66; −0.30 to 0.33) | .91 | ||||
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Emotional eating | 0.00 (0.79; −0.34 to 0.34) | .99 | 0.171 (0.67; −0.15 to 0.49) | .28 |
At 3 months, adolescents’ self-reported quality of life improved in the school (mean 8.3; 95% CI 0.6-16.1;
This pilot study is one of the few studies to evaluate the implementation of a multicomponent mobile app as an early intervention before enrollment in an adolescent WMC. The Kurbo pilot was successful in reaching a low-income and racially diverse population. Although there was no significant reduction in BMI z-scores, there were significant improvements in fat percentage, total caloric intake, and quality of life, suggesting potential benefits of enrolment and the need for a more formal randomized trial.
Obtaining a reach of 58% is comparable with that of other pediatric obesity studies [
Kurbo participants completed a median of 7 (IQR 2-10) coaching sessions. This level of engagement is considered very low (<10 hours of intervention time) based on the US Preventive Special Task Force criteria [
Our results show that the maximal period of engagement with Kurbo occurred in the first 7 weeks, which corresponded to the period between the initial WMC referral and the first WMC clinic visit. This suggests that Kurbo may be helpful in engaging participants as an early intervention before the first WMC visit. Early engagement may account for the increase in WMC attendance at 6 months (20/40, 50% attendance) compared with our historical rate of 42.1% (51/121). The use of a mobile app as an early intervention also provided mutual benefits to both the health care provider team and Kurbo health coaches. The administrator platform allowed the multidisciplinary team to gain a better understanding of patient progress in health behaviors and weight before presenting to the clinic. This allowed for more targeted discussions about barriers that adolescents faced in the management of obesity and more efficient care. Kurbo health coaches were able to highlight any concerns that they faced during the health coaching sessions of the health care team.
A challenge with Kurbo as an early intervention was the high attrition rate. Although the study’s dropout rate of 50% (20/40) is less than the in-clinic rate of 57.8% (70/121), it suggests that strategies need to be crafted to reduce attrition if Kurbo is to be successfully used as an early-stage intervention. Further research on the reasons for attrition is recommended.
Despite the lack of changes in BMI z-scores, a significant improvement in quality of life is an important finding. Quality of life among adolescents with overweight is lower than that among normal-weight peers [
Reassuringly, our study found no measured increase in disordered eating behaviors, as measured by the EPI-C. On the basis of these results, the integrated model of a mobile app with multidisciplinary adolescent obesity management is unlikely to increase disordered eating behaviors despite concerns for the development of disordered eating habits with the use of mobile apps [
This study had several limitations. The study had a small sample size and a high attrition rate. Second, as this was a feasibility study, the study did not include a control group.
In this pilot study, the use of the Kurbo mobile app as an early intervention before a multidisciplinary clinical care for adolescent obesity treatment is feasible in a low-income and ethnically diverse Asian population. Although there was no significant change in the BMI z-score, Kurbo showed promise in improving quality of life and reducing body fat percentage and total caloric intake. Given the promising outcomes in several dimensions, further research using more rigorous trial designs should be conducted to evaluate the effects of Kurbo as part of an early, stepped care intervention for adolescents with obesity.
Eating Pattern Inventory for Children
KK Women’s and Children’s Hospital
mobile health
moderate-to-vigorous physical activity
weight management clinic
The authors thank Kurbo for providing the data for this study. Kurbo was not involved in the design of the study, the analysis and interpretation of the data, or the preparation and submission of this manuscript. The authors wish to thank the patients and their families for their participation in the study and members of the pediatric weight management team for their contribution to the study. The study was funded by the Pediatrics Academic Clinical Programme/Tan Cheng Lim Fund grant PAEDACP-TCL/2017/CLIN/006.
EAF is on the scientific advisory board for WW Int (formerly Weight Watchers), the company that now owns Kurbo.