From the bench to public health: population-level implementation intentions in colorectal cancer screening.

Abstract

Early detection of colorectal cancer (CRC) using fecal occult blood test (FOBT) reduces mortality, yet screening adherence remains low. Enhancing FOBT adherence in a field experiment, using Implementation Intentions (II) technique. Participants were randomly assigned to a standard care group or to II experimental group. A test kit was mailed to 29,833 HMO-insured members in two waves in 2011. eligible persons aged 50-74 who underwent the test the year before. A sample of 2200 participants was interviewed over the telephone for possible cognitive and background moderators. Leaflet attached to the test kit containing an "if-then" condition and planning instructions of when, where, and how. Test performance at 2 and 6 months following mailing of the test kit, retrieved from HMO's computerized database (2011-2012). Adherence in the experimental group ranged 1.2%-6.6% higher than in the control group. Within 6 months of kits' mailing, test uptake for the two waves was 71.4% and 67.9% for experiment and control, respectively (χ(2)=40.58, p=0.0001). The difference remained significant after controlling for age, gender, marital status, and wave (OR=1.17, 95% CI=1.11, 1.23, p<0.0001). Test performance was related to cognitive and background variables. No interaction was found among cognitive or background variables and the intervention. II technique is useful in increasing adherence to CRC screening, even in a mailed form rather than a face-to-face experimental situation. Mailed II is an inexpensive and effective method, applicable for public health.