Effect of a pre-screening survey on attendance in colorectal cancer screening: A double-randomized study in Finland

Objectives: To explore effects of a pre-screening life style survey on the subsequent attendance proportion in colorectal cancer screening. Setting: Finnish colorectal cancer screening programme in 2011. Design: Double randomized and controlled follow-up design. Methods: The study population comprised of 31,951 individuals born in 1951. In 2010 to a random sample of every sixth (n = 5,312) person we sent a 7-paged life style questionnaire, and to another random sample of every sixth person (n = 5,336) a 10-paged life style and quality of life questionnaire. One year later, in 2011, 31,484 individuals of the original cohort were independently randomized (1: 1) for colorectal cancer screening (n = 15,748) or control group (n = 15,736). Of those who were invited for screening, 5185 had received a questionnaire during the previous year. Results: 5870 individuals (55.1 %) responded to the questionnaire in 2010. The overall attendance at screening in 2011 was 59.0 % in those born in 1951 (i.e. the 60-year-olds). In those who had been sent the survey the attendance in screening was 56.6% (57.3% for the short and 56.0% for the long questionnaire) and in those who had not received the questionnaire it was 60.2% (P < 0.001). Conclusions: We believe that the observed reduction in attendance in those who had been sent a questionnaire earlier is generally true. Thus, if any survey is enclosed in the screening invitation, this finding should be taken into account when planning the programme. Any extra effort requested may reduce the attendance proportion for screening, reducing the population level impact of screening.