The value of GP endorsement on participation in rescreening for colorectal cancer

Improved participation in screening for bowel cancer is desirable. Large scale screening programs must recruit invitees through comprehensive population registers. Depending on the country and health system these may be primary care practice lists or other registers such as the electoral roll. If primary care patient lists are available, considerable practice time may be required to organise the screening program, alternatively the implicit practice endorsement of screening may increase the participation rate to make that investment worthwhile. As screening is most effective when conducted regularly, it is important to determine if any increase in participation rate due to practice or practitioner endorsement is maintained over several rounds of screening offers. This study aims to follow screening participation over 4 rounds of offers in 4 treatment groups, and to use innovative statistical methods to determine the value of practice involvement in re-sceening participation.