Inflammatory bowel disease may be causal risk for psoriasis, psoriatic arthritis

Inflammatory bowel disease was found to have a positive association with both psoriasis and psoriatic arthritis, suggesting it is a causal risk factor for these two chronic diseases, according to a study.

“Some previous cross-sectional and prospective epidemiological studies as well as meta-analyses have reported an increased risk of [inflammatory bowel disease (IBD)] in patients with psoriasis and vice versa,” Dennis Freuer, PhD, chair of epidemiology at the University of Augsburg, University Hospital of Augsburg in Augsburg, Germany, and colleagues wrote. “The pathophysiologic mechanisms underlying this relationship are not fully understood, but there is little doubt that IBD and psoriasis likely share a common pathogenesis.”

The bidirectional, two-sample, mendelian randomization study included up to 463,372 European individuals from genome-wide association studies.

The discovery sample included 12,882 clinically diagnosed IBD cases base on up to 15 studies. The study also analyzed 5,956 Crohn’s disease cases, 6,968 ulcerative colitis cases, 5,621 psoriasis cases and 2,063 psoriatic arthritis cases to assess the association with the diseases.

Mendelian randomization analyses revealed that genetically predicted IBD has a causal link with both psoriasis (pooled OR = 1.1; 95% CI, 1.05-1.15) and psoriatic arthritis (pooled OR = 1.1; 95% CI, 1.04-1.18), but not vice versa. Subgroup analyses suggest that Crohn’s disease, but not ulcerative colitis, could also have a positive association with psoriasis (OR = 1.16; 95%CI, 1.12-1.2) and psoriatic arthritis (OR = 1.13; 95% CI, 1.06-1.2).

“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 IBD will contribute to systematic diagnosis and interdisciplinary and early personalized treatment of patients,” the researchers wrote.