Objective: To evaluate the level of informed decision making in a randomized controlled trial comparing colonoscopy and CT-colonography for colorectal cancer screening.
Methods: 8844 citizens aged 50-75 were randomly invited to colonoscopy (n=5924) or CT-colonography (n=2920) screening. All invitees received an information leaflet. Screenees received a questionnaire within 4 weeks before the planned examination, non-screenees 4 weeks after the invitation. A decision was categorized as informed when characterized by sufficient decision-relevant knowledge and consistent with personal attitudes toward participation in screening.
Results: Knowledge and attitude items were completed by 1032/1276 colonoscopy screenees (81%), by 698/4648 colonoscopy non-screenees (15%), by 824/982 CT-colonography screenees (84%) and by 192/1938 CT-colonography non-screenees (10%). 1027 colonoscopy screenees (>99%) and 815 CT-colonography screenees (99%) had adequate knowledge; 915 (89%) and 742 (90%) had a positive attitude. 675 non-screenees invited to colonoscopy (97%) and 182 invited to CT-colonography (95%) had adequate knowledge; 344 (49%) and 94 (49%) expressed a negative attitude.
Conclusion: A large majority of screenees made an informed decision on participation. Almost half of responding non-screenees, made an uninformed decision, suggesting additional barriers to participation.
Practice implications: Efforts to understand the additional barriers will create opportunities to facilitate informed participation to colorectal cancer screening.
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