Time Schedules for Sending Invitations to Colonoscopy Screening

The attendance rate to population based primary screening colonoscopy within NordICC trial (The Nordic-European Initiative on Colorectal Cancer, NCT00883792) in Poland is roughly 33%. The aim of this study is to compare the effect of two different time schedules for sending invitations and reminding letters to a pre-specified colonoscopy appointment. 1,600 screening naive men and women 55 to 64 years of age are randomly assigned in a 1:1 ratio to receive invitation and reminder 6 and 3 weeks (SIX and THREE group) or 4 and 2 weeks (FOUR and TWO group) prior to pre-specified screening colonoscopy appointment date. Outcome measures are participation in screening colonoscopy within 6 months from the date of invitation, response and acceptance rate before sending a reminder. The study is powered to detect 7% difference in participation in screening colonoscopy.