Formative evaluation of the usability and acceptability of myfood24 among adolescents: a UK online dietary assessments tool

Background: Myfood24 is a new online 24 h dietary assessment tool developed for use among the UK population. Limited information is available on the usability and acceptability of such tools. Hence this study aims to determine the usability and acceptability of myfood24 among British adolescents (11-18y) before and after making the improvements. Methods: A total of 84 adolescents were involved in two stages. In stage-I (beta-version of myfood24), 14 adolescents were recruited, 7 of whom (group-1) were asked to enter standardized tasks in a testing room with screen capture software. The remaining 7-adolescents (group-2) were asked to report their previous food intake using myfood24 at home. All participants then completed a usability and acceptability questionnaire. Stage-II was carried out after making amendments to the live-version of myfood24 in which 70 adolescents were asked to enter their food intake for two days and then complete the same questionnaire. Thematic analysis was conducted of observer comments and open-ended questions. Results: Navigation, presentation errors and failure to find functions were the main usability issues identified in the beta-version. Significant improvements were found in the usability and acceptability of most functions after implementing certain features like a spell checker, auto-fill option, and adding ‘mouse hover’ to help with the use of some functions. Adolescents’ perceptions of searching food items, selecting food portion sizes and making a list function were significantly improved in the live-version. The mean completion time of myfood24 reduced from 31 (SD = 6) minutes in the beta-version to 16 (SD = 5) minutes in the live-version. The mean system usability score (SUS) of myfood24 improved from 66/100 (95 % CI 60, 73) in the beta-version to 74/100 (95 % CI 71, 77) in the live-version, which is considered as ‘good’. Of the adolescents in stage-II, 41 % preferred using myfood24 to the interviewer-administered 24 h recall because myfood24 was quicker, easier to use and provided the adolescents with privacy when reporting dietary intake. Conclusion: Considering adolescents’ feedback has helped in improving the usability and acceptability of the final-version of myfood24. myfood24 appears to support adolescents’ need in reporting their dietary intake, which may potentially improve the overall quality of adolescents’ self-reported dietary information.