Does a decision aid improve informed choice in mammography screening? Study protocol for a randomized controlled trial

BACKGROUND When invited for the first time at age 50, most women in Germany have to decide whether they wish to participate in the German mammography screening programme. For ethical reasons, screening decisions should be informed choices, but this is rarely the case with mammography screening. Decision aids are interventions with the potential to support informed choice by improving the following factors: knowledge, clarity of personal attitude, and implementation of an intention. Currently, no systematically evaluated decision aid exists for the German mammography screening programme. Therefore, the objective of this randomized controlled trial is to assess the effectiveness of a decision aid for first-time mammography screening programme invitees. METHODS/DESIGN We have developed a decision aid for women invited to the mammography screening programme for the first time based on the criteria of the International Patient Decision Aids Standards Collaboration. The effectiveness of the decision aid will be evaluated in a randomized controlled trial with a 3-month follow-up. We will invite 7400 women aged 50 years from the district of Westfalen-Lippe, Germany, to participate. This sample will be drawn from registration office data. The primary outcome will be informed choice. The secondary outcomes will be the components of informed choice (knowledge, attitude, decision/implementation). Decisional conflict, decision regret, eHealth literacy, health behaviours, perceived behavioural control, subjective norms, invitation status, and demographic variables will be assessed. Data will be collected online at baseline, post-intervention, and at the 3-month follow-up. Participants will be randomized to receive either the decision aid or usual care (invitation and standard leaflet of the mammography screening programme). DISCUSSION This paper describes the evaluation of a decision aid for the German mammography screening programme in a randomized controlled trial. If the decision aid proves to be an effective tool to enhance the rate of informed choice, it will be made accessible to the public and the use of this decision aid for first-time invitees will be recommended. The long-term effect could be an improvement in informed choices in women invited to the mammography screening programme. TRIAL REGISTRATION German Clinical Trials Register DRKS00005176.