Colon Cancer: Risk Perceptions and Risk Communication

Abstract

Members of a health maintenance organization (N = 353) interacted with a computer program that provided personalized information about their risk of developing colon cancer in the next 20 years. Prior to computer feedback, most people greatly overestimated their numerical, absolute risk (chances per 1000) and also overestimated their relative risk compared to peers (e.g., “above average”). Their relative risk estimates were correlated with several risk factors, whereas their absolute risk estimates were not, suggesting that assessing individual risk perceptions with numerical, absolute risk scales may provide misleading information about what people believe. Computer feedback improved the accuracy of mean risk estimates, but about half of participants did not accept the personalized feedback as correct. In fact, correlations between actual and perceived risk were no greater among participants who received risk scores than among those who did not. Three possible explanations for resistance to lower-than-expected risk feedback are considered.

This research was supported in part by funding from Canyon Ranch Inc., and by Liberty Mutual Insurance Company.

Notes

Note: Entries are the percentage of the sample that underestimated risk, were accurate, and overestimated risk, respectively.

^aD_c ²(4) = 42.8, p < .0001.

^bD_c ²(4) = 14.4, p < .01.

Note: Absolute risk is indicated in chances per 1,000 in next 20 years. Rating scale for relative risk is 0 = very much below average to 6 = very much above average.

^a p < .001 for tests of differences among values in this column. Means sharing the same subscript are not significantly different.

Note. Correlations in parentheses are based on absolute risk judgments recoded to a maximum of 200 in 1000.

^a p < .05.

^b p < .01.

^c p < .001.

^d p < .0001.

¹ Vernon et al. (2001), using a dichotomous risk scale created from four questions about feelings of vulnerability, also reported a lack of association of perceived risk with age and education, but positive associations with worry and prior screening.