The effective practice of evidence-based medicine requires the application of ‘current best evidence’ to individual patient care.1 While there is consensus that it is critical to include patients' individual preferences in medical decision-making,1,–,4 the best way to involve patients in the process is unclear. Patient preferences may be dictated by specific circumstances, such as age, as well as by past experiences and cultural values. Increasingly, evidence shows that both health outcomes and patient decision-making are strongly associated with health literacy,5,–,12 which is not routinely assessed during clinical encounters.

Health literacy is defined by the Institute of Medicine as ‘the degree to which individuals have the capacity to obtain, process and understand basic health information and services needed to make appropriate health decisions.’5 Problems with health literacy are common, and the Institute of Medicine estimates that more than 90 million adults in the USA have difficulties reading, interpreting or managing health-related information.5

Low health literacy is associated with poor health outcomes, even when findings are adjusted …