• Anne Ahrendt Bjerregaard, Daniel E Zoughbie, HansenJørgen VinsløvJVDepartment of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark., Charlotta Granström, Marin Strøm, Þórhallur Ingi Halldórsson, Inger Kristine Meder, Walter Churchill Willett, Eric L Ding, and Sjúrður Fróði Olsen.
• Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
• PLoS Med. 2024 Jun 1; 21 (6): e1004383e1004383.

BackgroundFew cost-effective strategies to shift dietary habits of populations in a healthier direction have been identified. We examined if participating in a chatbot health education program transmitted by Short Messages Service ("SMS-program") could improve adolescent dietary behaviors and body weight trajectories. We also explored possible added effects of maternal or peer involvement.Methods And FindingsWe conducted a randomized controlled trial (RCT) among adolescents from the Danish National Birth Cohort (DNBC). Eligible were adolescents who during 2015 to 2016 at age 14 years had completed a questionnaire assessing height, weight, and dietary habits. Two thirds were offered participation in an SMS-program, whereas 1/3 ("non-SMS group") received no offer. The SMS program aimed to improve 3 key dietary intake behaviors: sugar-sweetened beverages (SSBs), fruit and vegetables (FV), and fish. The offered programs had 3 factorially randomized schemes; the aims of these were to test effect of asking the mother or a friend to also participate in the health promotion program, and to test the effect of a 4-week individually tailored SMS program against the full 12-week SMS program targeting all 3 dietary factors. Height and weight and intakes of SSB, FV, and fish were assessed twice by a smartphone-based abbreviated dietary questionnaire completed at 6 months (m) and 18 m follow-up. Main outcome measures were (1) body mass index (BMI) z-score; and (2) an abbreviated Healthy Eating Index (mini-HEI, 1 m window, as mean of z-scores for SSB, FV, and fish). Among the 7,890 randomized adolescents, 5,260 were assigned to any SMS program; 63% (3,338) joined the offered program. Among the 7,890 randomized, 74% (5,853) and 68% (5,370) responded to follow-ups at 6 m and 18 m, respectively. Effects were estimated by intention-to-treat (ITT) analyses and inverse probability weighted per-protocol (IPW-PP) analyses excluding adolescents who did not join the program. Mean (standard deviation (SD)) mini-HEI at baseline, 6 m and 18 m was -0.01 (0.64), 0.01 (0.59), and -0.01 (0.59), respectively. In ITT-analyses, no effects were observed, at any time point, in those who had received any SMS program compared to the non-SMS group, on BMI z-score (6 m: -0.010 [95% confidence interval (CI) -0.035, 0.015]; p = 0.442, 18 m: 0.002 [95% CI -0.029, 0.033]; p = 0.901) or mini-HEI (6 m: 0.016 [95% CI -0.011, 0.043]; p = 0.253, 18m: -0.016 [95% CI -0.045, 0.013]; p = 0.286). In IPW-PP analyses, at 6 m, a small decrease in BMI z-score (-0.030 [95% CI -0.057, -0.003]; p = 0.032) was observed, whereas no significant effect was observed in mini-HEI (0.027 [95% CI -0.002, 0.056]; p = 0.072), among those who had received any SMS program compared to the non-SMS group. At 18 m, no associations were observed (BMI z-score: -0.006 [95% CI -0.039, 0.027]; p = 0.724, and mini-HEI: -0.005 [95% CI -0.036, 0.026]; p = 0.755). The main limitations of the study were that DNBC participants, though derived from the general population, tend to have higher socioeconomic status than average, and that outcome measures were self-reported.ConclusionsIn this study, a chatbot health education program delivered through an SMS program had no effect on dietary habits or weight trajectories in ITT analyses. However, IPW-PP-analyses, based on those 63% who had joined the offered SMS program, suggested modest improvements in weight development at 6 m, which had faded at 18 m. Future research should focus on developing gender-specific messaging programs including "booster" messages to obtain sustained engagement.Clinical Trial RegistrationClinicalTrials.gov Identifier: NCT02809196 https://clinicaltrials.gov/study/NCT02809196.Copyright: © 2024 Bjerregaard et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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