Effects of graphic presentation on understanding medical risks and benefits among Japanese adults

Abstract Abstract: The purpose of this study was to identify the method of presentation (text, bar graphs, or pictographs) that best enhances the understanding of medical risk information among Japanese adults. We also investigated the effect of graphic format on understanding by differences in numeracy. This is the first study conducted in Japan to clarify understanding the risks and benefits of treatment. Participants were randomized to receive numerical information about the risks and benefits of a hypothetical medical treatment in one of three formats: text, bar graphs, or pictographs. The main outcome variables were adequate verbatim and adequate gist understanding. In total, 1062 individuals (text, 354; bar graphs, 358; and pictographs 350) were included in the analysis. Pictographs and bar graphs did not show significant differences from text in conferring verbatim information. However, pictographs significantly differed from text in conferring gist information (odds ratio [OR] 1.567, 95% confidence interval [CI] 1.097–2.237), but bar graphs did not significantly differ from text (OR 1.390, 95%CI 0.983–1.964). Numeracy was the factor most strongly associated with adequate verbatim and gist understanding. Our results suggest that although pictographs appear to be an effective option, their effectiveness is limited to people with higher numeracy and people with lower numeracy may have little benefit from pictographs.