An app promoting weight gain prevention via healthy behaviours amongst young women with a family history of breast cancer: Acceptability and usability assessment.

Background: Breast cancer is the most frequent female malignancy in the UK. Around 20% of cases are linked to weight gain, excess weight and health behaviours. We designed a weight gain prevention, health behaviour intervention for young women at increased risk.

Methods: The study comprised a single arm observational study over 2 months testing acceptability and usability of the intervention: online group welcome event, app and private Facebook group. Females aged 18-35 years at moderate or high risk of breast cancer (>17% lifetime risk) were recruited via invite letters and social media posts. The app included behaviour change techniques and education content. Online questionnaires were completed at baseline, as well as at 1 and 2 months. We also assessed feasibility of study procedures.

Results: Both recruitment methods were successful. Thirty-five women were recruited, 26% via social media posts. Median age was 33 (interquartile range = 28.2-34.5) years, the majority (94.1%) were of White ethnicity. Thirty-four participants were included in the analyses, of which 94% downloaded the app. Median self-monitoring logs per participant during the study period was 10.0 (interquartile range = 4.8-28.8). App quality mean (SD) score was 3.7 (0.6) at 1 and 2 months (scale: 1-5). Eighty-nine per cent rated the app at average or above at 1 month and 75.0% at 2 months. Nineteen women (55.9%) joined the Facebook group and there were 61 comments and 83 reactions and votes from participants during the study period.

Conclusions: This first iteration of the app and intervention was well received and is suitable to progress to the next stage of refining and further testing.