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Open Access Research article

Should a colon cancer screening decision aid include the option of no testing? A comparative trial of two decision aids

Jennifer M Griffith1*, Marlie Fichter2, Floyd J Fowler2, Carmen Lewis13 and Michael P Pignone13

Author Affiliations

1 Center for Decision Making Research, Cecil Sheps Center for Health Services Research, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA

2 Foundation for Informed Medical Decision Making, 40 Court Street, Suite 300, Boston, MA 02108, USA

3 Division of General Internal Medicine, School of Medicine, University of North Carolina- Chapel Hill, Chapel Hill, North Carolina, USA

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BMC Medical Informatics and Decision Making 2008, 8:10  doi:10.1186/1472-6947-8-10

Published: 5 March 2008



An important question in the development of decision aids about colon cancer (CRC) screening is whether to include an explicit discussion of the option of not being screened. We examined the effect of including or not including an explicit discussion of the option of deciding not to be screened in a CRC screening decision aid on subjective measures of decision aid content; interest in screening; and knowledge.


Adults ages 50–85 were assigned to view one of two versions of the decision aid. The two versions differed only in the inclusion of video segments of two men, one of whom decided against being screened. Participants completed questionnaires before and after viewing the decision aid to compare subjective measures of content, screening interest and intent, and knowledge between groups. Likert response categories (5-point) were used for subjective measures of content (eg. clarity, balance in favor/against screening, and overall rating), and screening interest. Knowledge was measured with a three item index and individual questions. Higher scores indicated favorable responses for subjective measures, greater interest, and better knowledge. For the subjective balance, lower numbers were associated with the impression of the decision aid favoring CRC screening.


57 viewed the "with" version which included the two segments and 49 viewed the "without" version. After viewing, participants found the "without" version to have better subjective clarity about benefits of screening ("with" 3.4, "without" 4.1, p < 0.01), and to have greater clarity about downsides of screening ("with" 3.2, "without" 3.6, p = 0.03). The "with" version was considered to be less strongly balanced in favor of screening. ("with" 1.8, "without" 1.6, p = 0.05); but the "without" version received a better overall rating ("with" 3.5, "without" 3.8, p = 0.03). Groups did not differ in screening interest after viewing a decision aid or knowledge.


A decision aid with the explicit discussion of the option of deciding not to be screened appears to increase the impression that the program was not as strongly in favor of screening, but decreases the impression of clarity and resulted in a lower overall rating. We did not observe clinically important or statistically significant differences in interest in screening or knowledge.