Anti-TNFα antibody-induced psoriasiform skin lesions in patients with inflammatory bowel disease: an Irish Cohort Study

Aim: To determine the prevalence of psoriasis in an IBD cohort with reference to clinical characteristics and anti-TNF alpha use. Methods: Patients with psoriasis and IBD were retrospectively identified from the IBD database at Tallaght Hospital from 2000 to 2015. Pertinent clinical data were obtained from patients notes including anti-TNF alpha exposure. Prevalence rates of genuine and reactive psoriasis were calculated and compared using Student's T-test. A P values of <0.05 was considered significant. Results: In total, 1384 IBD patients were identified. The overall prevalence rate of IBD and psoriasis was 2.4% (n = 33), with 1.8% (n = 25) in the Crohn's disease group and 0.6% (n = 8) in the ulcerative colitis group. Within the psoriasis group, 24% (n = 8 of 33) had reactive psoriasis. The prevalence rates of psoriasis in the non-biological and biological cohorts were similar 2.5% (25 of 981) and 2% (8 of 403), respectively. There was no significant association with reactive psoriasis and disease type. There was a trend towards higher rates of reactive psoriasis Adalimumab users, 3.6% (6 of 166) vs. 0.8% (2 of 237), OR = 4.283, P = 0.077, 95% CI 0.854-21.483 in infliximab users. In addition, in our cohort, smoking was not associated with any form of psoriasis in IBD, OR = 1.377, 95% CI 0.061-3.087, P = 0.437. Conclusion: In our large study, the prevalence rate of reactive psoriasis was similar to the background rate of psoriasis in the overall IBD cohort (2.0 vs. 2.4%). A 2% prevalence rate represents a common adverse event that clinicians should be aware of.