Clinical implications of numeracy: theory and practice.

BACKGROUND: Low numeracy is pervasive and constrains informed patient choice, reduces medication compliance, limits access to treatments, impairs risk communication, and affects medical outcomes; therefore, it is incumbent upon providers to minimize its adverse effects.
PURPOSE: We provide an overview of research on health numeracy and discuss its implications in clinical contexts.
CONCLUSIONS: Low numeracy cannot be reliably inferred on the basis of patients' education, intelligence, or other observable characteristics. Objective and subjective assessments of numeracy are available in short forms and could be used to tailor health communication. Low scorers on these assessments are subject to cognitive biases, irrelevant cues (e.g., mood), and sharper temporal discounting. Because prevention of the leading causes of death (e.g., cancer and cardiovascular disease) depends on taking action now to prevent serious consequences later, those low in numeracy are likely to require more explanation of risk to engage in prevention behaviors. Visual displays can be used to make numerical relations more transparent, and different types of displays have different effects (e.g., greater risk avoidance). Ironically, superior quantitative processing seems to be achieved by focusing on qualitative gist and affective meaning, which has important implications for empowering patients to take advantage of the evidence in evidence-based medicine.