[Improving comprehension and communication of risks about health].

Many patients have severe difficulties grasping several numerical concepts that are related to their health, such as, for instance, the risk of suffering various diseases. Visual aids have been proposed as a promising method for enhancing risk communication and comprehension. In medical practice, however, not all patients benefit from visual aids. In a study conducted on a probabilistic, representative national sample in the United States, we identified a group of patients for whom visual aids are most useful: Those who have low numeracy but high graphical literacy skills. These patients have high scores in three abilities involved in graph comprehension: (1) the ability to read the data, (2) the ability to read the relations between the data, and (3) the ability to read beyond the data. Our results can have important implications for medical practice and for risk communication about health.