Background: Current UK policy has highlighted the importance of patient involvement in treatment decisions. Computerised decision aids have the potential to increase patient involvement in the decision-making process. However, published evidence concerning decision aids is primarily from secondary care.

Purpose: To evaluate whether the addition of a computerised decision aid using decision analysis, to written information improves decision-making in women consulting their General Practitioner (GP) with menorrhagia (heavy menstrual bleeding) compared with written information alone.

Methods: Randomised controlled trial of a complex intervention with qualitative evaluation. Women (n=149) from 19 Family Practices in UK, attending GP with menorrhagia were randomised to receive written information and access to a computerised decision aid, or written information alone. Outcomes (decisional conflict, anxiety, menorrhagia quality of life, knowledge and process measures) were obtained using postal questionnaires. The intervention group was purposively sampled for semi-structured interviews (n=18).

Results: 138 (95%) returned the 2 week follow-up and 116 (84%) returned the 6 month follow-up. Reduction in decisional conflict was greater in the intervention group (difference in means -16.6, 95% CI -21.5 to -11.7; p<0.001). At 6 months, the intervention group showed greater improvements in knowledge scores (difference in means 9.3, 95% CI 1.9 to 16.6; p<0.01); and menorrhagia quality of life (difference in means 10.9, 95% CI 0.9 to 21.0; p<0.05). There was no difference in anxiety at 2 weeks or 6 months follow-up.

Qualitative analysis revealed a lack of knowledge of menorrhagia and its treatment options. The decision aid had a greater impact than written information because it was perceived as interactive, personalised and containing specific risk information. Using the decision aid led to women reporting feeling more enabled to participate in future decisions about their treatment.

Conclusions: A computerised decision aid, used outside of the primary care consultation, is effective in increasing patient involvement in decision making in primary care. Issues to be considered in future research include different methods of providing this intervention (on-line or as a resource in a health centre).