The influence of initial screening test technology on participation in rescreening for colorectal cancer

Interventions: The aim is to determine the effect of the type of test offered in a first round of a screening program for colorectal cancer on participation in a second round.
Group 1: First round of screening Hemoccult II Sensa, low technology test. Second round of screening: InSure test, high technology.
Group 2: First round of screening: FlexSure OBT, mid technology test. Second round: InSure OBT, high technology.
Group 3: First round of screening: InSure OBT, high technology test. Second round: InSure OBT, high technology.
Primary outcome(s): Paricipation in screening defined as return of a screening kit 12 weeks from offer.[]
Study Design: Purpose: Prevention; Allocation: Randomised controlled trial; Masking: Blinded (masking used);Assignment: Parallel;Type of endpoint: Efficacy