A randomized controlled trial of the effectiveness of a pre-recruitment primer letter to increase participation in a study of colorectal screening and surveillance

Background: Recruiting cancer patients is a barrier often encountered in research trials. However, very few randomized trials explore strategies to improve participation rates. The purpose of this study was to evaluate the effectiveness of a pre-recruitment primer letter to recruit persons diagnosed with colorectal cancer for a research trial. Methods. Potentially eligible participants were identified by the Victorian Cancer Registry. A total of 1,062 participants were randomized to receive either a mailed explanatory primer letter designed to encourage research participation, or no primer letter. Two weeks after the intervention, the Victorian Cancer Registry sought permission from patients to release their contact details to researchers. Those who agreed were contacted and invited to the study. Results: Pre-recruitment encouragement was not effective at increasing recruitment, with no significant differences demonstrated between experimental groups. Overall, 40% (n = 425) consented to participate, 25% (n = 243) refused and 35% (n = 394) did not respond. Conclusions: While this study demonstrated disappointing outcomes, pre-recruitment letters should not be ruled out as an approach altogether. Rather, future research should explore whether other factors to increase motivation, such as intensity and timing, are feasible and acceptable for contacting cancer patients.