Genetic, Lifestyle Factors Independently Linked to IBD Risk

FRIDAY, Jan. 27, 2023 (HealthDay News) -- Genetic and lifestyle factors are independently associated with the risk for Crohn disease (CD) and ulcerative colitis (UC), according to a study published online Jan. 6 in The American Journal of Gastroenterology.

Yuhao Sun, M.B.B.S., from the Zhejiang University School of Medicine in Hangzhou, China, and colleagues examined the impact of genetic and lifestyle factors on CD and UC risk. Genetic susceptibility to CD and UC was estimated by polygenic risk scores, and risk was categorized into high, intermediate, and low categories. In addition, healthy lifestyle scores were constructed based on five common lifestyle factors and lifestyle was categorized into favorable, intermediate, and unfavorable (four or five, three, and zero to two factors, respectively). Overall, 707 CD cases and 1,576 UC cases were diagnosed during the 12-year follow-up.

The researchers observed monotonic associations for genetic risk and unhealthy lifestyle categories with CD and UC risk, with no multiplicative interaction between them. For those with high genetic risk, the hazard ratios of CD and UC were 2.24 and 2.15, respectively. For individuals with unfavorable lifestyle, the hazard ratios for CD and UC were 1.94 and 1.98, respectively. For individuals with high genetic risk but favorable lifestyle, the hazard ratios were reduced nearly by half to 2.33 and 2.05 for CD and UC, respectively, while for those with high genetic risk but unfavorable lifestyle, the hazard ratios were 4.40 and 4.44 for CD and UC, respectively.

"An unfavorable lifestyle was associated with a higher risk of CD and UC in individuals regardless of genetic strata," the authors write.

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