Patient decision aids are interventions and/or tools that are designed to translate evidence into tools that at a minimum, a) make explicit the decision to be made; b) inform patients about their options; c) help them clarify the value that they place on benefits versus harms; and d) guide them in the process of decision making. Formats for these tools include paper-based booklets, video/DVDs, decision boards, and Internet-based materials. Patient decision aids are used as adjuncts to practitioner counselling for decisions where the best choice depends on how patients weigh the benefits, risks and scientific uncertainty.