Intention to be screened over time for colorectal cancer in male automotive workers.

Intention is an important construct in health promotion research, yet very little is known about whether cross-sectional correlates of intention to be screened for colorectal cancer (CRC) also predict intention over time or intention change. We used survey data from The Next Step Trial, a worksite health promotion trial, to address the following questions: (1) What is the consistency over time of intention to be screened for CRC? (2) Are the patterns and magnitude of associations between intention to be screened and the Preventive Health Model variables consistent over time? (3) What are the predictors of improving weaker intention to be screened, i.e., changing to strong intention? (4) What are the predictors of no change in strong intention to be screened, i.e., maintaining strong intention? and (5) What is the predictive ability of the models to predict intention to be screened for CRC? The study population consisted of white male automotive employees who responded to baseline (1993) and follow-up (1994 and 1995) surveys and did not have CRC at baseline or develop it during the study period. Of 5042 eligible workers, 2903 (58%) returned a baseline survey, and 2556 (88% of survey responders) met eligibility criteria; 75% (1929 of 2556) returned the year 1 survey, and 74% (1892 of 2556) returned the year 2 survey. We fit logistic regression models separately for the Preventive Health Model variables measured at baseline and each outcome (intention at year 1, intention at year 2, improving weaker intention, and no change in strong intention). The prevalence of strong intention to be screened for CRC was approximately 60% on all three surveys. Overall, 66% maintained their baseline intention over time. The most consistent predictors of strong intention, improving weaker intention, and no change in strong intention were family support, belief in the salience and coherence of screening, prior screening, and lack of concern about screening-related discomfort. Intention measured at baseline predicted intention measured 1 and 2 years later. Perceived susceptibility and lack of fear and worry about a CRC diagnosis predicted improving weaker intention. Having a family history of CRC or polyps predicted maintaining strong intention. Plant factors, self-efficacy, and beliefs about polyp removal were not predictors beyond the baseline year. Basing intervention development on cross-sectional associations may miss important factors or may incorrectly assume that cross-sectional associations are stable over time. A more focused, tailored intervention may be developed using factors that consistently predict intention.