Dataset for a randomised factorial experiment to optimise an information leaflet for women with breast cancer

Most women with breast cancer are prescribed adjuvant endocrine therapy (AET) to prevent recurrence and mortality, but adherence is low. Negative beliefs about the necessity of AET and high concerns are barriers to adherence. We aimed to optimize the content of an information leaflet intervention, to support AET beliefs. We conducted an online screening experiment using a 2^5 factorial design to optimize the leaflet. The leaflet had five candidate components, each operationalised as factors with two levels; 1) diagrams about AET mechanisms (on/off); 2) infographics displaying AET benefits (enhanced/basic); 3) AET side-effects (enhanced/basic); 4) answers to AET concerns (on/off); 5) breast cancer survivor (patient) input: quotes and photographs (on/off). Healthy adult women (n=1604), recruited via a market research company, were randomized to one of 32 experimental conditions, which determined the combination of components received. Participants completed the beliefs about medicines questionnaire before and after viewing the leaflet. After viewing the leaflet, participants also completed a modified version of the satisfaction with information about medicines questionnaire to assess their satisfaction with information received about AET, and eight true/false questions about AET, to assess their knowledge about AET after reading the leaflet.