Toward understanding nonparticipation in sigmoidoscopy screening for colorectal cancer.

Understanding the reasons for nonparticipation in cancer screening may give clues about how to improve compliance. However, limited cooperation has hampered research on nonparticipant profiles. We took advantage of Sweden's comprehensive demographic and health care registers to investigate characteristics of all participants and nonparticipants in a pilot program for colorectal cancer screening with sigmoidoscopy. A population-based sample of 1986 Swedish residents 59-61 years old was invited. Registers provided information on each individual's gender, country of birth, marital status, education, income, hospital contacts, place of residence, distance to screening center and cancer within the family. Odds ratios (ORs) with 95% confidence intervals (CIs), modeled with multivariable logistic regression, estimated the independent associations between each background factor and the propensity for nonparticipation after control for the effects of other factors. All statistical tests were 2-sided. Being male (OR = 1.27, 95% CI = 1.03-1.57, relative to female), unmarried or divorced (OR = 1.69, 95% CI = 1.23-2.30 and OR = 1.49, 95% CI = 1.14-1.95, respectively, relative to married) and having an income in the lowest tertile (OR = 1.68, 95% CI = 1.27-2.23, relative to highest tertile) was associated with increased nonparticipation. Living in the countryside or in small communities and having a documented family history of colorectal cancer was associated with better participation. Distance to the screening center did not significantly affect participation, nor did recent hospital care consumption or immigrant status. To increase compliance, invitations must appeal to men, unmarried or divorced people and people with low socioeconomic status.