How to Design Effective Child Growth Apps, Not Just Attractive Ones: Evaluating the design of child growth chart apps and investigating end-user design preferences and effective design for an app-based child growth chart

Abstract

Child growth charts are tools used by clinicians and parents to monitor the growth of children under the age of 5. Paper-based growth charts are the norm, but they are widely reported to be poorly understood. By bringing the growth chart onto a digital platform such as the mobile ‘app’ and using basic design elements, it may be possible to improve understanding of child growth and increase caregiver involvement in healthy child growth. Aims and objectives This study aims to explore two aspects of child growth charts; firstly, the app design preferences of users of child growth charts; and secondly, the most effective way to present child growth information in an app. The specific research objectives are: to explore existing research in this field; to evaluate existing child growth chart apps to identify the limitations of existing apps and inform app development; to identify parents’ and other child caregivers’ preferences in growth chart app design and investigate the effectiveness of different growth chart designs at communicating growth information; and to understand how health apps can be more responsive to the needs and preferences of their users. Methods I reviewed the literature on child growth, practices around child growth monitoring, mobile phones and health apps within healthcare delivery and the place of design within health IT. Next, I reviewed the design of existing growth chart apps using an app evaluation tool, MADRS, adapted from the Mobile App Rating Scale (MARS). The designs that emerged in this review were replicated and adapted for an online survey targeting parents and caregivers of infants, promoted through relevant online channels. In the survey, participants were asked a series of questions to determine design preferences of growth chart apps and the most effective way to present growth information. The resulting data were analysed using simple descriptive statistics. All data in the form of text were read, re-read, sorted and collated to identify key themes. Findings The literature review highlighted that while child growth charts are an essential tool to monitor child growth, parents often poorly understand them. Parents and caregivers tend to use visual examinations to classify child weight and size rather than growth charts which are objective, but these tend to underestimate the actual weight of children. There is a paucity of research on whether digital growth charts can influence user understanding and action. Within healthcare, user experience frameworks are being seen to be of growing importance as they place people at the centre and focus on how services can better meet user needs and preferences. Almost half of all reviewed apps evaluated scored at an acceptable, poor or inadequate level of engagement (n=6), functionality (n=5) and aesthetics (n=4). High scoring apps (“Baby Daybook,” “Child Growth Standards,” “Child Chart,” “Child growth and percentiles”) consistently scored above 4/5 for all domains and mostly received overall perceived design ratings of 4. Three hundred and forty-three people took part in the online survey. Participants’ preferences for app design features did not always align with approaches used in current child growth chart apps: 57% of participants (160/281) preferred having access to multiple growth charts on a single screen versus a single growth chart on the screen (favoured by 37%; 103/281). Similarly, 76% (213/281) of participants preferred a simplified neutral approach to presenting percentile lines compared to the standard method of red and green lines used by the World Health Organisation (WHO) (20%; 55/281). The survey also explored how basic design elements may be used within growth chart apps to improve understanding. Participant’s; ability to identify a child’s percentile increased from 79% (168/214) to 90% (192/213), ability to choose an appropriate follow-up action when a child has had a rapid weight gain increased from 69% (213/307) to 80% (241/300), and participants were more able to make judgements about growth curves. Conclusion In this study, the preferences of people taking part in an online survey on the design of child growth chart apps did not always align with the design features of available child growth chart apps. Design preferences are important to aid understanding; therefore, developers should gauge user preferences through robust user experience research when developing such health apps. Basic design elements improved participant’s abilities to identify aspects of growth charts, determine growth curve meaning and what action should be undertaken next compared to no design elements. Elements of growth chart app design appeared to be linked and enabled by one another, thus focussing on one aspect of design and not others is likely to cause the overall design to suffer. Applying a design-orientated framework and methodology for developing child growth chart apps may help improve parent and caregiver growth chart comprehension and interpretation, and thereby improve child health.