Incidence of psoriasiform diseases secondary to tumour necrosis factor antagonists in patients with inflammatory bowel disease: a nationwide population‐based cohort study

Summary Background There are increasing reports of paradoxical psoriasiform diseases secondary to anti‐tumour necrosis factor ( TNF ) agents. Aims To determine the risks of paradoxical psoriasiform diseases secondary to anti‐ TNF agents in patients with inflammatory bowel disease (IBD). Methods A nationwide population study was performed using the Korea National Health Insurance Claim Data. A total of 50 502 patients with IBD were identified between 2007 and 2016. We compared 5428 patients who were treated with any anti‐ TNF agent for more than 6 months (anti‐ TNF group) and 10 856 matched controls who had never taken anti‐ TNF agents (control group). Results Incidence of psoriasis was significantly higher in the anti‐ TNF group (36.8 per 10 000 person‐years) compared to the control group (14.5 per 10 000 person‐years) (hazard ratio [ HR ] 2.357, 95% confidence interval [ CI ] 1.668‐3.331). Palmoplantar pustulosis ( HR 9.355, 95% CI 2.754‐31.780) and psoriatic arthritis ( HR 2.926, 95% CI 1.640‐5.218) also showed higher risks in the anti‐ TNF group. In subgroup analyses, HR s for psoriasis by IBD subtype were 2.549 (95% CI 1.658‐3.920) in Crohn's disease and 2.105 (95% CI 1.155‐3.836) in ulcerative colitis. Interestingly, men and younger (10‐39 years) patients have significantly higher risks of palmoplantar pustulosis ( HR 19.682 [95% CI 3.867‐100.169] and HR 14.318 [95% CI 2.915‐70.315], respectively), whereas women and older (≥40 years) patients showed similar rates between the two groups. Conclusions The risks of psoriasiform diseases are increased by anti‐ TNF agents in patients with IBD . Among psoriasiform diseases, the risk of palmoplantar pustulosis shows the biggest increase particularly in male and younger patients.