BACKGROUND: Few interventions to increase colorectal cancer screening have used a stage of change model to promote screening adoption. None have used computer-assisted tailored telephone counseling calls. This study's purpose was to implement and evaluate stage-based computer-assisted tailored telephone counseling to promote colorectal cancer screening in a primary care population.

METHODS: This randomized controlled trial used a two-stepped intervention that included a mailed booklet on colorectal cancer screening followed by computer-assisted telephone counseling that was based on the Precaution Adoption Process Model. Chart audit was used to document completion of colonoscopy, sigmoidoscopy or fecal occult blood testing.

RESULTS: Record audits were completed on 2,474 (88%) of the 2,817 eligible participants. There was no significant difference in the frequency and nature of the screening tests completed in the study arms. In a sub-analysis, stages of adoption were evaluated pre- and post-telephone counseling. Over half those receiving counseling reported a change in stage towards screening adoption.

CONCLUSION: Overall, the intervention did not increase colorectal screening compared to control. Two possible reasons for the absence of a screening effect include: (a) the focus of the protocol on education for most patients rather than motivation, and (b) the requirement that patients interested in screening seek further information and a referral on their own from their providers. While those receiving telephone counseling improved their stage of adoption, we cannot rule out selection bias. Stronger physician recommendation to speak with the counselors could improve call acceptance. Future colorectal screening should address these weaknesses.