Medical Decision Making (MDM)
May/June 2011; 31 (3)
http://mdm.sagepub.com/content/current

Risk Communication
Ellen Peters, P. Sol Hart, and Liana Fraenkel
Informing Patients: The Influence of Numeracy, Framing, and Format of Side Effect Information on Risk Perceptions
Med Decis Making May/June 2011 31: 432-436, first published on December 29, 2010 doi:10.1177/0272989X10391672

Abstract
Background. Given the importance of effective patient communication, findings about influences on risk perception in nonmedical domains need replication in medical domains. Objective. To examine whether numeracy influences risk perceptions when different information frames and number formats are used to present medication risks. Methods. The authors manipulated the frame and number format of risk information in a 3 (frame: positive, negative, combined) × 2 (number format: frequency, percentage) design. Participants from an Internet sample (N = 298), randomly assigned to condition, responded to a single, hypothetical scenario. The main effects and interactions of numeracy, framing, and number format on risk perception were measured. Results. Participants given the positive frame perceived the medication as less risky than those given the negative frame. Mean risk perceptions for the combined frame fell between the positive and negative frames. Numeracy did not moderate these framing effects. Risk perceptions also varied by number format and numeracy, with less-numerate participants given risk information in a percentage format perceiving the medication as less risky than when given risk information in a frequency format; highly numerate participants perceived similar risks in both formats. The generalizability of the findings is limited due to the use of non-patients, presented a hypothetical scenario. Given the design, one cannot know whether observed differences would translate into clinically significant differences in patient behaviors. Conclusions. Frequency formats appear to increase risk perceptions over percentage formats for less-numerate respondents. Health communicators need to be aware that different formats generate different risk perceptions among patients varying in numeracy.

Debra Sprague, Donna L. LaVallie, Fredric M. Wolf, Clemma Jacobsen, Kirsten Sayson, and Dedra Buchwald
Influence of Graphic Format on Comprehension of Risk Information among American Indians
Med Decis Making May/June 2011 31: 437-443, first published on December 29, 2010 doi:10.1177/0272989X10391096

Abstract
Background. Presentation of risk information influences patients’ ability to interpret health care options. Little is known about this relationship between risk presentation and interpretation among American Indians. Methods. Three hundred American Indian employees on a western American Indian reservation were invited to complete an anonymous written survey. All surveys included a vignette presenting baseline risk information about a hypothetical cancer and possible benefits of 2 prevention plans. Risk interpretation was assessed by correct answers to 3 questions evaluating the risk reduction associated with the plans. Numeric information was the same in all surveys, but framing varied; half expressed prevention benefits in terms of relative risk reduction and half in terms of absolute risk reduction. All surveys used text to describe the benefits of the 2 plans, but half included a graphic image. Surveys were distributed randomly. Responses were analyzed using binary logistic regression with the robust variance estimator to account for clustering of outcomes within participant. Results. Use of a graphic image was associated with higher odds of correctly answering 3 risk interpretation questions (odds ratio = 2.5, 95% confidence interval = 1.5–4.0, P < 0.001) compared to the text-only format. These findings were similar to those of previous studies carried out in the general population. Neither framing information as relative compared to absolute risk nor the interaction between graphic image and relative risk presentation was associated with risk interpretation. Conclusion. One type of graphic image was associated with increased understanding of risk in a small sample of American Indian adults. The authors recommend further investigation of the effectiveness of other types of graphic displays for conveying health risk information to this population.

Mirta Galesic and Rocio Garcia-Retamero
Graph Literacy: A Cross-Cultural Comparison
Med Decis Making May/June 2011 31: 444-457, first published on July 29, 2010 doi:10.1177/0272989X10373805

Abstract
Background. Visual displays are often used to communicate important medical information to patients. However, even the simplest graphs are not understood by everyone. Objective. To develop and test a scale to measure health-related graph literacy and investigate the level of graph literacy in the United States and Germany. Design. Experimental and questionnaire studies. Setting. Computerized studies in the laboratory and on probabilistic national samples in the United States and Germany. Participants. Nationally representative samples of people 25 to 69 years of age in Germany (n = 495) and the United States (n = 492). Laboratory pretest on 60 younger and 60 older people. Measurements. Psychometric properties of the scale (i.e., reliability, validity, discriminability) and level of graph literacy in the two countries. Results. The new graph literacy scale predicted which patients can benefit from visual aids and had promising measurement properties. Participants in both countries completed approximately 9 of 13 items correctly (in Germany, x¯ = 9.4, s = 2.6; in the United States, x¯ = 9.3, s = 2.9). Approximately one third of the population in both countries had both low graph literacy and low numeracy skills. Limitations. The authors focused on basic graph literacy only. They used a computerized scale; comparability with paper-and-pencil versions should be checked. Conclusions. The new graph literacy scale seems to be a suitable tool for assessing whether patients understand common graphical formats and shows that not everyone profits from standard visual displays. Research is needed on communication formats that can overcome the barriers of both low numeracy and graph literacy.