139 The risk of lymphoma in patients with psoriasis: A cohort study in the United Kingdom

Abstract

Prior studies have suggested an increased risk of lymphoma in patients with psoriasis. However, it is unclear if this risk is due to the chronic inflammatory nature characteristic of this disease, exposure to immunosuppressive therapies, or a combination of both factors. To further explore this association, we conducted a cohort study using a large population-based electronic medical records database of patients in the UK. The outcomes of interest were incident diagnosis of any lymphoma, Hodgkin’s lymphoma, or cutaneous T-cell lymphoma. A total of 198,4676 patients with psoriasis (186,172 with mild and 12,304 with moderate-to-severe disease as defined by use of systemic or phototherapy) and 939,095 patients without psoriasis (matched on practice and visit date with psoriasis patients), were included in the analysis. The adjusted hazard ratios (95% CI) for incident any lymphoma were 1.35 (1.19, 1.52), 1.32 (1.16, 1.50), and 1.84 (1.22, 2.79) in the overall, mild and severe psoriasis groups. The adjusted hazards ratios for cutaneous T-cell lymphoma for the overall, mild and severe psoriasis group were 3.51 (2.36, 4.81), 3.17 (2.09, 4.81), and 9.16 (3.96, 21.22), respectively. The results were robust to multiple sensitivity analyses including exclusion of patients with rheumatoid and psoriatic arthritis, and exclusion of patients with exposure to methotrexate, cyclosporine, and/or any biologic. No statistically significant associations were seen with Hodgkin’s lymphoma. In this large observational study, the risk of incident lymphoma and cutaneous T-cell lymphoma was higher in patients with psoriasis compared to patients without psoriasis. This risk appears to be higher in patients with moderate-to-severe disease, and is independent of traditional risk factors and exposure to immunosuppressive medications including methotrexate, cyclosporine or biologics.