There seems to be a causal effect between inflammatory bowel disease and psoriasis and psoriatic arthritis, according to a study published online Sept. 14 in JAMA Dermatology .

Dennis Freuer, Ph.D., from the University of Augsburg in Germany, and colleagues examined the association between inflammatory bowel disease and psoriasis or psoriatic arthritis in a bidirectional two-sample mendelian randomization study using summary statistics from genome-wide association studies, which included up to 463,372 European individuals. Total and direct effects were derived, and causal estimates were verified using a validation inflammatory bowel disease sample, a series of mendelian randomization methods, and sensitivity analyses.

The European samples included 12,882 inflammatory bowel disease cases and 5,621 psoriasis cases. The researchers found that the risks for psoriasis and psoriatic arthritis were increased with genetically predicted inflammatory bowel disease (pooled odds ratios, 1.10 and 1.10, respectively). Crohn disease subentity was associated with psoriasis and psoriatic arthritis (odds ratios, 1.16 and 1.13, respectively), while ulcerative colitis was not. No notable associations were identified in the reverse directions.

"The results of the study are critical because raising awareness among clinicians and primary care physicians about the potential risk of psoriasis in patients with inflammatory bowel disease will contribute to systematic diagnosis and interdisciplinary and early personalized treatment of patients," the authors write.

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