To estimate the differential effect of tumor necrosis factor inhibitor (TNFi) therapies and presence or absence of conventional synthetic disease-modifying antirheumatic drugs (DMARDs) on the incidence of psoriasis (PsO) in children with inflammatory bowel disease (IBD), juvenile idiopathic arthritis (JIA), and chronic nonbacterial osteomyelitis (CNO).
This was a retrospective cohort study from 2008 to 2020. TNFi and DMARD exposures were dichotomized as ever/never. The primary outcome was incident PsO. Incidence rates (IRs) of PsO were stratified by underlying diagnosis, TNFi agent, and DMARD use. Poisson regression was used to assess the IR ratios (IRRs) between exposure groups.
There were 5088 children who met the inclusion criteria: 3794 (75%) had IBD, 1189 (23%) had JIA, and 105 (2%) had CNO. Of the 2023 children with TNFi exposure, 613 (30%) and 1410 (70%) were with or without a DMARD, respectively. When controlling for DMARD, sex, and family history of PsO, the IRR of developing PsO in patients exposed to adalimumab (ADA) was 2.70 times higher (95% CI 1.53-4.75; 
IRR of TNFi-induced PsO was not significantly different among ADA, IFX, and ETN. However, for patients with exposure to any of the TNFi evaluated, the IRR was significantly lower in those also exposed to a DMARD.