Background Infliximab (IFL) is a monoclonal tumour necrosis factor alpha inhibiting antibody which is frequently used to treat children with refractory arthritis and uveitis. The most frequent and limiting adverse events are anaphylactic infusion reactions caused by anti-drug antibodies.

Objectives The objective of our study was to describe the frequency and the long-term course of anaphylactic reactions in a cohort of patients treated with IFL.

Methods After a search of the rheumatology database the charts of all patients treated with IFL were retrospectively reviewed for IFL infusion reactions. Factors such as IFL dosage, infusion interval, co-medication and the time until the first occurrence of an infusion reaction were collected, as well as the treatment and course since the first infusion reaction until the last follow up visit.

Results A total of 2098 IFL infusions were given to 78 patients (22 male, 56 female) between Oct 2000 and Dec 2011. Indication for IFL use was refractory JIA in 46 pat (59%), uveitis in 15 pat (19%) and both arthritis and uveitis in 13 pat (17%), while 4 pat (5%) had other systemic inflammatory diseases. The mean IFL treatment duration was 3.7 years. All patients received co-medication with methotrexate or leflunomide. Allergic infusion reactions (respiratory or gastrointestinal symptoms, rash, malaise or low blood pressure)occurred in 35 infusions (1.7% of all infusions) of 11 patients (14%). Allergic reactions occurred after a mean treatment time of 340 (range 41-780) days. In 6/11 patients the allergic reaction was preceded by arthritis flare. Four patients chose to stop treatment immediately because of the allergic reaction. For the other 7 patients we didn’t discontinue IFL treatment after allergic reaction, but used high dose antihistamine premedication and in 5/7 pat methylprednisolon premedication for the following infusions. Additionally we reduced the IFL infusion interval in 4/7 pat and increased the IFL dose in 2/7 pat. 2 pat pursued the treatment with the same IFL interval and dose. With this regimen 5 patients (71%) were able to continue IFL treatment for a mean of 2.8 years while 2 patients discontinued because of repeated allergic reactions.

Conclusions Allergic infusion reactions occurred in 14% of our patients. Treatment with antihistamine drugs, methylprednisolon and increased/more frequent IFL administration allowed >70% of our patients to continue IFL treatment despite allergic reactions. We hypothesize that the continued IFL administration led to desensitization.

Disclosure of Interest None Declared