Making numbers matter: present and future research in risk communication.

OBJECTIVE: To summarize existing research on individual numeracy and methods for presenting risk information to patients. METHODS: We selectively retrieved articles from MEDLINE and the Social Sciences Citation Index. RESULTS: Many Americans have low numeracy skills, a deficit that impedes effective health care. Approaches to risk communication vary in current practice, but how risks are presented can significantly affect both patients' risk perceptions and their knowledge. CONCLUSIONS: Adhering to some basic principles for presenting risk information to patients can improve understanding. However, different risk-communication methods may be needed for individuals with high versus low levels of numeracy.