Helping women make choices about mammography screening : An online randomized trial of a decision aid for 40-year-old women

Objective: To evaluate the effect of a decision aid (DA) on women's knowledge of the benefits and harms of screening and on their ability to make an informed decision.

Methods: An online randomized controlled trial among 321 women aged 38–45 years was conducted. Participants were randomized to either immediate or delayed access to the online DA which (i) explained the benefits and harms, (ii) included a values clarification exercise and a worksheet to support decision making. The primary outcome, knowledge of benefits and harms of screening, and secondary outcomes, informed choice (composite of knowledge, values and intention), anxiety and acceptability of the DA were measured using online questionnaires.

Results: Women in the intervention group were more knowledgeable (mean score out of 10, 7.35 vs 6.27, p < 0.001) and were more likely to have made a decision (82% vs 61% p < 0.001). Of those who made a decision, women in the intervention group were less likely to start screening now (52% vs 65% p = 0.05). There was no significant difference in the proportion of women who made an informed choice (71% intervention group vs 64% control group, p = 0.24). The DA was helpful, balanced and clear, and did not make women anxious.

Conclusions: The DA increased knowledge and reduced indecision, without increasing feelings of anxiety.

Practice Implications: This decision aid is easy to access online and could be an inexpensive way of supporting women aged 40 who are considering whether to start screening now, or wait until they are 50. The results of this study demonstrate the potential of DAs to help inform women about both the benefits and risks of screening at this age and to support women and clinicians in this decision making process.