Abstract
Objective: The success of national cancer screening programs, such as the National Bowel Cancer Screening Program (NBCSP) in Australia, depends on public participation, which is currently an alarming 43.5% for the NBCSP. Understanding the barriers that impede screening participation requires valid measurement instruments. This study aims to cross-validate such an instrument with a new, large, and varied sample, as well as assess measurement invariance across subsamples at a greatest risk of nonparticipation (ie, testing whether the scale functions in similar ways across groups).
Design, Setting, and Participants: A cross-sectional sample of 1158 participants from the target screening population (50-74 years) provided demographic information, responses to the Barriers to Home Bowel Screening (BB-CanS) scale, and information on their previous screening participation.
Results: Both the full and the brief versions of the BB-CanS scale showed good model fit for the full sample and for gender and age subsamples. Despite the inter-factor correlations being high, the unidimensional and bi-factor models exhibited poorer fit. Improvement in fit was observed with scale refinement involving the removal of 7 items. All versions of the BB-CanS scale were invariant across gender and age subsamples. Age and gender differences emerged across several barriers and variance in all 4 barriers significantly predicted prior screening participation.
Conclusion: The BB-CanS scale is a valid measure of 4 highly correlated barriers to home bowel cancer screening: disgust relating to screening, avoidance of test outcomes, practical difficulty (or challenges), and the need for a sense of greater autonomy. All versions of the instrument measure the equivalent construct across age and gender groups. Observed differences in barriers across at-risk groups provide targets for future intervention.