1. Introduction
satiety, appetite
RECRUITMENT
There has been no validated digital tool for measuring appetite with a visual analog scale (VAS) through a mobile app using participants’ smart phones for data collection in virtual settings. To fill the gap, we developed a digital VAS and conducted a digital cross-over clinical trial by comparing appetite responses measured by this digital tool versus paper-based VAS in 102 participants in a free-living environment. Participants consumed either a 230 or 460 kcal breakfast in randomized order in two virtual sessions, and their appetite was measured over the next 4 h using both tools. The results revealed no significant difference in hunger, fullness, satiety, or desire to eat measured by digital and paper VAS. Paper VAS resulted in a higher prospective consumption score than digital VAS; the difference (1.1 out of 100 points) was statistically significant but not practically relevant. Bland and Altman analysis also indicated consistency in the results from the two methods. In conclusion, digital VAS on a smart phone is a validated tool for appetite measurement in the real world; it provides a new way for researchers to leverage participants’ mobile devices for appetite data collection in digital trials.Designing foods with greater satiating properties is a potential approach to address increased consumer need for weight management. To assess satiating properties of food or to measure human appetite, certain tools have been developed and validated in laboratory settings. Typically, appetite is measured with paper and pen using self-reported questions with responses captured by lines or Likert scales; although unipolar unstructured line (visual analog scale, VAS) is the most widely used method to measure appetite in clinical trials [Over the past two decades, various portable devices have been developed and validated for appetite measurement, such as the Newton-based electronic appetite rating system (EARS) [Digital clinical trials have gained increased attention during the COVID-19 pandemic as researchers explore methods to virtually conduct clinical trials. This involves digital technology for execution of a clinical trial with participant recruitment, data collection, and analytics [To the best of our knowledge, there has been no validated digital tool for measuring appetite using VAS through a mobile app with participants using their own smart phones in remote settings. Nonetheless, development and validation of such tools are of particular importance for future research applications, considering potential benefits such as reduced research cost, reduced burden to participants and researchers, convenience for use in large-scale digital clinical trials or observational studies, and improved participant engagement and data quality.The objective of our study was to develop and validate a mobile app-based VAS for appetite measurement in digital clinical trials. Validity was assessed by comparing a newly developed digital VAS with the traditional paper and pen-based VAS for appetite measurements.