MINISTOP 2.0: a smartphone app integrated in primary child health care to promote healthy diet and physical activity behaviours and prevent obesity in preschool-aged children: protocol for a hybrid design effectiveness-implementation study

Childhood obesity is still a major global health issue [1]. In 2019, 38 million children under the age of five were overweight or obese [2]. Sweden is no exception with 10–15% of 4-year-olds being overweight or obese [3, 4]. Although increases in the prevalence of obesity have generally been shown to level off in developed countries [1, 5], recent data indicate that obesity is still increasing among school-aged children in Sweden [6]. As in other high-income countries, there is a socioeconomic gradient of obesity in Sweden, with a higher prevalence already in young childhood among socioeconomically disadvantaged or migrant families [7‐9]. In addition, only 33 and 20% of Swedish preschool-aged children fulfil recommendations for physical activity and the intake of fruit and vegetables, respectively [10, 11]. Childhood obesity and obesity-related behaviours, such as low physical activity and unhealthy diet, tend to track into adulthood [12‐14] where they are associated with increased risk of disease, impaired psychosocial well-being and premature death [5, 15‐17]. Given these serious health consequences, prevention of obesity and promotion of health behaviours in childhood are major public health priorities.

Preschool age (2–5 years) has been identified as a critical period to intervene [18], and primary child health care has been regarded as an important setting for obesity treatment and prevention efforts [19]. However, to date, interventions for this age group have only reported limited effectiveness for obesity prevention and improvement of health behaviours [19‐24]. Furthermore, effective interventions that can decrease childhood obesity inequalities in preschool-aged children are lacking [9]. Collectively, these findings highlight the need for innovative solutions to facilitate obesity prevention in young children.

During the last decade, digitalisation and advancements in mobile phone technology have radically changed communication and offer new opportunities to improve how health care services are delivered. For instance, mobile phone technologies have been successfully integrated into interventions to promote healthy diets, physical activity and weight loss [25, 26]. The benefits of using mobile phone based (mHealth) versus more traditional face-to-face interventions are that they can be delivered at any time or place and participants do not have to attend a clinic (or the number of visits can be reduced). Also, given the ubiquitous use of mobile phones, irrespectively of socioeconomic status, mHealth offers the ability to deliver relatively low-cost interventions at scale [27].

A novel mHealth obesity prevention trial in preschool-aged children, the MINISTOP (Mobile-based Intervention Intended to Stop Obesity in Preschoolers) 1.0 trial, was conducted 2013–2015 in a population-based sample of Swedish children [28]. The MINISTOP 1.0 smartphone app had a high participation rate and usage by parents. The efficacy evaluation showed no group difference in fat mass index; however, children in the app group had higher odds of improving a composite score of six dietary and activity behaviours (OR: 2.0; 95% CI 1.2–3.1; p = 0.008). The effect of the intervention on dietary and activity behaviours was more pronounced in the children with a higher fat mass index (p = 0.019), which is promising as these children need it the most. It is noteworthy that the effect size was greater or equal to more labour-intense traditional, face-to-face delivered interventions [23, 24]. However, the MINISTOP 1.0 app was provided to the families by researchers, which is not feasible in real life conditions. Therefore, the next step is to evaluate the MINISTOP app in a primary child health care context in order to investigate its effectiveness and implementation. To optimise accessibility, the MINISTOP 1.0 app has been translated and tailored for priority populations, such as children with a migrant background (≈25% of all Swedish children) [29] who are less likely to participate in population-based health strategies [30]. Furthermore, the MINISTOP 1.0 app has been modified based on feedback and requirements from users, i.e. parents and health care providers. The effectiveness and implementation of this revised version of the app (called MINISTOP 2.0) will be evaluated in real life conditions, i.e. in routine child health care. This project (called the MINISTOP 2.0 trial) has been initiated in close collaboration with Swedish primary child health care. The MINISTOP 2.0 trial is one of seven mHealth interventions in the MoBILE research programme (principal investigator: ML) aiming to promote healthy lifestyle habits [31].

The MINISTOP 2.0 trial will evaluate whether an mHealth intervention embedded in the routine services provided by primary child health care can be used to improve diet and physical activity behaviours and prevent overweight and obesity in preschool-aged children. Most previous interventions using digital delivery methods targeting children have been conducted in older children and do not involve parents [48]. The few mHealth intervention trials that have been conducted in children under 3 years of age have had relatively small sample sizes, but have shown promising results [49, 50]. The MINISTOP 2.0 trial is the first study, to the best of our knowledge, to evaluate an intervention delivered by a smartphone app embedded in routine child health care.

Our trial has several strengths including the hybrid type 1 study design, which allows for the testing of the effectiveness of MINISTOP 2.0 and assessment of various implementation aspects. Blending effectiveness and implementation studies provides benefits over carrying out these types of studies independently. This design enables faster knowledge generation and increased usefulness of clinical research if effectiveness is proven [32]. Another strength is the randomised controlled trial design for the assessment of the effectiveness, a planned large sample size, and close collaboration with primary child health care. Participating children are recruited from primary child health care, where almost 99% of all children attend the routine visits [51]) from centres throughout Sweden covering various socioeconomic areas. Thus, the pragmatic blended study design, recruiting in real life conditions with non-restrictive inclusion criteria, increases the generalisability of the trial results. The intervention is grounded in Social Cognitive Theory [35] and uses well-recognised strategies for promoting behaviour change [36]. Considering that ≈25% of all Swedish children have a migrant background [29], another strength of the MINISTOP 2.0 trial is that the app has been translated from Swedish to three other prominent language groups in Sweden (English, Arabic and Somali). We target multiple health-related behaviours in the intervention, including healthy eating, physical activity, screen-time, dental health and sleep. Finally, the trial investigates the perceived acceptability, appropriateness and feasibility among both parents and primary child health care nurses, three aspects that are often considered as key indicators of implementation success [47]. The investigation of the implementation indicators is important for improved understanding of the external validity, i.e. how or the extent to which the results are relevant beyond the trial [52]. Thus, the trial offers the opportunity to generate valuable knowledge for future scale-up and widespread implementation of the app.

There are also some limitations included in the study design. The app has not been translated to all spoken languages in Sweden, and some families who speak minority languages will not be able to participate in the trial. Also, although parents from various socioeconomic backgrounds will be offered participation in the trial, it is possible that there will be an underrepresentation of families with lower education. We will, however, analyse whether there are any differences in intervention effect depending on socioeconomic status or migration background. We use self-reported data for some outcomes, which is common in large studies measuring lifestyle changes [53]. However, the combination of self-reporting and the lack of blinding of participants and nurses, who are responsible for data collection, increases the risk of differential social desirability bias between arms, and research participation effects more generally. This is, however, a consequence of the scale and pragmatic design of the trial, and our findings should be viewed under this limitation. The use of blended effectiveness-implementation designs can be challenging because researchers from clinical and implementation research tend to use different theories, concepts and constructs [32]. However, the clinical and implementation researchers in the MINISTOP 2.0 trial have collaborated from the outset of the trial, thus having developed efficient communication and a shared understanding of both spheres of research.

The MINISTOP 2.0 app has the potential to be implemented in primary child health care nationally, and thereby reach many families who may benefit from it. This is highly relevant considering that obesity is a major public health challenge globally as well as in Sweden. Primary child health care is an important arena for strategies to prevent childhood obesity and also decrease health inequalities [19, 51], as almost all preschool-aged children in Sweden, irrespective of socioeconomic status and migrant background, attend primary child health care [51]. If effective and feasible within the child health care setting, the MINISTOP 2.0 app has the potential to be an evidence-based, low-cost tool to aid primary child health care professionals in their work to promote healthy dietary and activity behaviours, prevent obesity as well as to decrease health inequalities already at preschool age.