The effect and psychological mediators of a redesigned invitation letter to increase bowel cancer screening intention and likelihood: A randomised controlled experiment.

BACKGROUND

Participation in the Australian National Bowel Cancer Screening Program (NBCSP) is low. Modifying the invitation letters sent with home bowel cancer screening kits may increase participation.

OBJECTIVES

This study compared current and modified versions of the NBCSP invitation letter to assess impact on intention to screen and perceived likelihood of screening and the role of screening barriers, enablers, and recipient characteristics.

METHODS

In an online survey, 700 Australians aged 50-74 years were randomly assigned to view either the current NBCSP invitation letter or a redesigned version featuring a deadline, a prompt to place the kit somewhere visible, and simple pictorial instructions. Intention to screen for bowel cancer, perceived likelihood of screening, and screening barriers and enablers were measured before and after letter exposure. Mixed ANOVA and ANCOVA were used to assess pre-post changes in screening outcome variables, the mediating role of changes in screening barriers and enablers, and the moderating effect of age, gender, education, and screening history.

RESULTS

Compared to the control letter, the redesigned letter was associated with an absolute increase in perceived screening likelihood of 2.8 %, F(1, 698) = 5.77, p = .017). This effect was mediated by increased screening benefits (b =.03, p = .019), self-efficacy (b =.03, p = .024), and planning to use the kit (b =.05, p = .008). Decreased perceived difficulty and avoidance mediated the effect of the resigned letter only among those who had never screened before (b = -0.04, p = .017), and males (b = 0.03, p = .045), respectively.

CONCLUSION

Invitation letters that highlight screening benefits and provide simple, practical guidance to support planning and self-efficacy may increase recipients' screening likelihood. Messaging reducing difficulty and avoidance barriers may be most effective for males and those who have not screened previously.