Safety of biologic therapy in combination with methotrexate in moderate to severe psoriasis: a cohort study from the BIOBADADERM registry

Background Safety is an important consideration in decisions on treatment for patients with moderate-to-severe psoriasis and the study of drug safety is the main purpose of the BIOBADADERM registry. The combination of a biologic agent and a conventional systemic drug [generally methotrexate (MTX)] is a common treatment in clinical practice. However, there is a paucity of evidence from real-world practice on the safety of such combination regimens in the treatment of psoriasis. Objectives The primary objective of this study was to ascertain whether the use of regimens combining biologic drugs with MTX in the management of moderate-to-severe psoriasis increases the risk of adverse events (AEs) or serious AEs (SAEs). We compared monotherapy using tumour necrosis factor (TNF), interleukin (IL)-17 and IL-23 inhibitors with the use of the same drugs in combination with MTX. Methods Using data from the BIOBADADERM registry, we compared biologic monotherapies with therapies that were combined with MTX. We estimated adjusted incidence rate ratios (aIRR) using a random effects Poisson regression with 95% confidence intervals for all AEs, SAEs, infections and serious infections and other AEs by system organ class. Results We analysed data from 2829 patients and 5441 treatment cycles, a total of 12 853 patient-years. The combination of a biologic with MTX was not associated with statistically significant increases in overall risk of AEs or SAEs in any treatment group. No increase in the total number of infections or serious infections in patients receiving combined therapy was observed for any group. However, treatment with a TNF inhibitor combined with MTX was associated with an increase in the incidence of gastrointestinal AEs (aIRR 2.50, 95% CI 1.57-3.98; P < 0.002). Conclusions The risk of AEs and SAEs was not significantly increased in patients with moderate-to-severe psoriasis receiving different classes of biologic drugs combined with MTX compared with those on biologic monotherapy.