P134 : Effect of occult blood in feces on the risk of psoriasis: a nationwide population based cohort study

Background: The fecal immunochemistry test (FIT) has been proposed as a surrogate marker of intestinal inflammation. Psoriasis is a chronic inflammatory skin disease linked to inflammatory conditions, including psoriatic arthritis, cardiovascular disease, and inflammatory bowel disease. Objectives: To investigate the association between occult blood in feces, as indicated by a positive FIT result, and the risk of psoriasis in a South Korean population. Methods: We enrolled 1,395,147 individuals (> 50 years old) from the National Health Insurance System database who underwent health examinations from 2009 to 2012 and were followed up until December 31, 2017. We performed a Cox proportional hazards regression to calculate the association with the risk of psoriasis of the number of positive FIT results. Results: The incidence (1,000 person-years) of psoriasis was 3.76 vs. 4.14 (negative vs. positive FIT group) during a median follow-up of 6.68 years. Individuals with a greater number of positive FIT results were at higher risk of psoriasis. In the multivariable-adjusted model, the hazard ratios and 95% confidence intervals for psoriasis were 1.029 (0.997-1.061) for one positive FIT result, 1.118 (1.04- 1.201) for two positive FIT results, and 1.342 (1.157-1.557) for three positive FIT results compared with negative FIT results. Conclusion: Fecal hemoglobin is associated with an increased risk of psoriasis. The number of positive FIT results was linearly associated with the risk of psoriasis.