Infections in inflammatory bowel disease patients on immunomodulator and biologic therapy are not associated with high serum drug levels

Abstract

AbstractBackgroundInflammatory bowel disease (IBD) therapies now utilise higher doses of immunomodulatory and biologic therapies, predisposing patients to an increased risk of infections.AimsWe aimed to determine whether infections were associated with high anti‐tumour necrosis factor (TNF) drug levels in IBD and to quantify the risk and consequences of infections.MethodsTwo retrospective studies were performed, a descriptive cohort study and a matched case–control study. For the matched case–control study, cases of infection occurring on anti‐TNF agents were matched in a 1:2 ratio to controls of anti‐TNF treated patients without infections.ResultsIn the descriptive study, 76 infections occurred in 60 patients, including 49 bacterial, 24 viral, four fungal and four parasitic. Of these, 61 (80.3%) were on biologics, 49 (64.5%) on immunomodulators and 11 (14.5%) on corticosteroids. Thirty‐four (44.7%) were on combination therapy, 27 (35.5%) on biologic monotherapy and 15 (19.7%) on immunomodulator monotherapy. Median anti‐TNF drug levels in infection cases were 3.9 μg/mL for infliximab and 6.0 μg/mL for adalimumab. In the case–control study, 32 cases of infection in 27 anti‐TNF treated patients were matched with 64 anti‐TNF treated controls without infections. Among infection cases, 59.5% were on combination therapy versus 40.6% on biologic monotherapy (P = 0.59). Median drug levels for cases and controls respectively were 3.9 μg/mL versus 5.5 μg/mL for infliximab (P = 0.72) and 6.0 μg/mL versus 9.9 μg/mL for adalimumab (P = 0.34).ConclusionInfections in patients with IBD were common, and the risk was highest with combination therapy. Infections were not associated with high serum anti‐TNF levels.