Severe infusion reactions to infliximab: aetiology, immunogenicity and risk factors in patients with inflammatory bowel disease

Background  Infliximab (IFX) elicits acute severe infusion reactions in about 5% of patients with inflammatory bowel disease (IBD). Aim  To investigate the role of anti-IFX antibodies (Ab) and other risk factors. Methods  The study included all IBD patients treated with IFX at a Danish university hospital until 2010 either continuously (IFX every 4-12 weeks) or episodically (reinitiation after >12 weeks). Anti-IFX Ab were measured using radioimmunoassay. Results  Twenty-five (8%) of 315 patients experienced acute severe infusion reactions. Univariate analysis showed that patients who reacted were younger at the time of diagnosis (19 vs. 26 years, P = 0.013) and at first IFX infusion (28 vs. 35 years, P = 0.012). Furthermore, they more often received episodic therapy (72% vs. 31%, P