A randomized questionnaire-based study on the impact of providing numerical information on colorectal cancer screening.

Objectives: To establish whether the provision of numerical data using pictograms and framed as event rates affects subjects' attitudes to colorectal cancer (CRC) screening.

Design: Randomized questionnaire and telephone study comparing a control group given standard NHS CRC information leaflets with an intervention group given the same leaflet but enhanced with additional numerical and pictorial information.

Setting: District General hospital and two general practices in North East England. Study carried out immediately prior to the introduction of CRC screening.

Participants: A total of 478 non-gastroenterological subjects (age range 60-70 years).

Main Outcome Measures: The difference in the two groups' overall wish to be screened; comparison of the impact of enhanced vs. unenhanced summary points in the NHS information leaflet; the summary point that most influenced their decision on screening; the views of the intervention group on the additional numerical and pictorial information provided.

Results: A total of 256 (54%) responded (124 from the control group and 117 from the intervention group); 22% were interviewed by telephone; 90% of the control group and 85% of the intervention group wished to be screened (P = 0.34). Provision of numerical and pictorial information significantly changed the impact of five of the six summary points on the decision to be screened. Sixty-two percent of the intervention group found the pictograms helpful while 83% of those interviewed by telephone found the numerical data helpful; 73% of the control group when given by telephone the additional numerical information given to the intervention group said this would have been useful in aiding their decision-making.

Conclusion: Providing additional numerical information would enhance the credibility of the screening programme without necessarily reducing the numbers screened.