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In the fecal immunological test, a suitable cut-off value may be selected to classify results as either positive or negative. Our aim is to estimate the optimal cut-off value for detecting colorectal cancer in different age and sex groups. This is a multicentric retrospective cohort study of participants in CRC screening programs with FIT between 2006 and 2012. A total of 545,505 participations were analyzed. Cancers diagnosed outside of the program were identified after a negative test result (IC_test) up until 2014. The Wilcoxon test was used to compare fecal hemoglobin levels. ROC curves were used to identify the optimal cut-off value for each age and sex group. Screening program results were estimated for different cut-off values. The results show that the Hb concentration was higher in colorectal cancer (average = 179.6μg/g) vs. false positives (average = 55.2μg/g), in IC_test (average = 3.1μg/g) vs. true negatives (average = 0μg/g), and in men (average = 166.2μg/g) vs. women (average = 140.2μg/g) with colorectal cancer. The optimal cut-off values for women were 18.3μg/g (50-59y) and 14.6μg/g (60-69y), and 16.8μg/g (50-59y) and 19.9μg/g (60-69y) for men. Using different cut-off values for each age and sex group lead to a decrease in the IC_test rate compared to the 20μg/g cut-off value (from 0.40‰ to 0.37‰) and an increase in the false positive rate (from 6.45% to 6.99%). Moreover, test sensitivity improved (90.7%), especially in men and women aged 50-59y (89.4%; 90%) and women aged 60-69y (90.2%). In conclusion, the optimal cut-off value varies for different sex and age groups and the use of an optimal cut-off value for each group improves sensitivity and leads to a small decrease in IC_tests, but also to a larger increase in false positives., Competing Interests: The authors have declared that no competing interests exist.

Severe complications (SC) in colonoscopy represent the most important adverse effect of colorectal cancer screening programs (CRCSP). The objective is to evaluate the risk factors for SC in colonoscopy indicated after a positive fecal occult blood test in population-based CRCSP. The SC (n = 161) identified from 48,730 diagnostic colonoscopies performed in a cohort of all the women and men invited from 2000 to 2012 in 6 CRCSP in Spain. A total of 318 controls were selected, matched for age, sex and period when the colonoscopy was performed. Conditional logistic regression models were estimated. The analysis was performed separately in groups: immediate-SC (same day of the colonoscopy); late-SC (between 1 and 30 days after); perforation; and bleeding events. SC occurred in 3.30‰ of colonoscopies. Prior colon disease showed a higher risk of SC (OR = 4.87). Regular antiplatelet treatment conferred a higher risk of overall SC (OR = 2.80) and late-SC (OR = 9.26), as did regular anticoagulant therapy (OR = 3.47, OR = 7.36). A history of pelvic-surgery or abdominal-radiotherapy was a risk factor for overall SC (OR = 5.03), immediate-SC (OR = 8.49), late-SC (OR = 4.65) and perforation (OR = 21.59). A finding of adenoma or cancer also showed a higher risk of overall SC (OR = 8.71), immediate-SC (OR = 12.67), late-SC (OR = 4.08), perforation (OR = 4.69) and bleeding (OR = 17.02). The risk of SC doesn't vary depending on the type of preparation or type of anesthesia. Knowing the clinical history of patients such as regular previous medication and history of surgery or radiotherapy, as well as the severity of the findings during the colonoscopy process could help to focus prevention measures in order to minimize SC in CRCSP., (Copyright © 2018 Elsevier Inc. All rights reserved.)