Risk of advanced adenoma detection in colorectal cancer screening programmes according to personal characteristics and screening history.

The detection of advanced adenomas (AA) is an important benefit-relevant indicator in colorectal cancer screening programmes (CRCSP). The study hypothesis is that factors related to personal screening history and social characteristics may influence the risk of detecting AA. We performed a retrospective study of men and women aged between 50 and 69 who participated in the Valencia Region CRCSP between 2010 and 2018. Variables: sex, age, number of previous negative faecal occult blood tests (FOBT), and faecal Hb concentration in the previous FOBT (Prev-f-Hb). We analysed the risk of AA and the influence of factors related to screening history in the first screening attendance (First_A) (n = 594,242) and in the most recent screening attendance (Recent_A) (n = 388,558) for people who had participated on at least two occasions. Logistic multivariate models were used to estimate odds ratios (OR). The risk of AA in First_A was higher in men (OR = 2.59; 2.50-2.68) and in the 60-69 age group (OR = 1.62; 1.57-1.67). In Recent_A, the risk was higher in the population with a Prev-f-Hb of greater than 0 ng/mL, and this risk increased for 0.1-19.9 ng/mL, 20-39.9 ng/mL, 40-59.9 ng/mL, 60-79.9 ng/mL, and 80-99.9 ng/mL (women: OR = 1.70, OR = 3.78, OR = 7.05, OR = 9.98, OR = 14.1 and men: OR = 1.66, OR = 3.61, OR = 5.69, OR = 8.45, OR = 10.30, respectively). The risk was lower in the population with four or five previous negative FOBT (OR = 0.76, 0.68-0.85; OR = 0.53, 0.41-0.66). Demographic characteristics and screening history could be used to design risk-adapted screening strategies.