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P639 Is there a correlation between infliximab trough levels and the development of adverse events in patients with inflammatory bowel disease?

E. Theodoraki*1, E. Orfanoudaki1, K. Foteinogiannopoulou1, E. Legaki2, M. Gazouli2, I. Koutroubakis1

1University Hospital of Heraklion, Gastroenterology Department, Heraklion, Greece, 2Laboratory of Biology, Medical School, National and Kapodistrian University of Athens, Athens, Greece

Background

The measurement of infliximab trough levels (IFX-TLs) in patients with inflammatory bowel disease (IBD) has been suggested as a useful tool for the treatment optimisation. The association between the development of adverse events (AEs) of IFX and IFX-TLs has not been adequately studied so far. The aim of this study was to investigate the possible association of IFX-TLs with AEs in Greek patients with IBD under maintenance treatment with IFX.

Methods

Retrospective analysis of registered data of patients with at least one available measurement of IFX-TLs for the years 2016–2017 was applied. All AEs reported 4 months before and 4 months after measurement of IFX-TLs were recorded. The IFX-TLs of patients with or without AEs were compared.

Results

A total of 83 IBD patients [CD 61 (73.5%), UC 22 (26.5%), men 52 (63%), median age (IQR) 42 years (31–54), CD-L1 23 (38%), CD-L2 13 (21%), CD-L3 25 (41%), UC-E2 8 (36%), UC-E3 14 (64%)] were included. The median (IQR) time since the diagnosis was 9 (6–17) years whereas 48 patients (58%) were under immunosupressants (40 AZA and 8 MTX) and 6 (7%) under intensified dose of IFX. A total of 147 IFX-TLs were available with a median value of 4.69 (1.32–9.16) μg/ml and 99 (67.3%) AEs were reported of which 13 (13.1%) considered as severe requiring hospitalisation. Among the AEs 48 (48.5%) were related to infections, 27 (27.3%) to skin reactions and the other 24 (24.2%) to various causes (hypersensitivity reactions, cancers, less frequently neurological or musculoskeletal disorders, psychiatric reactions, general symptoms like fatigue or dizziness and abnormal laboratory tests). From 48 infections reported, 36 (75%) were referred to respiratory and 6 (12.5%) to urinary track. Median IFX-TLs of patients with AE (total) were 5.79 (1.36–10.25) μg/ml, higher than those without AE [3.40 (1.30–5.92)], but not statistically significant (p = 0.071). Patients also with infections had higher, but not statistically significant, IFX-TLs than patients without infections [5.99 (1.64–9.09) vs. 3.75 (1.28–9.33), p = 0.16]. There was also no difference of IFX-TLs according to the presence or absence of dermatologic reactions [5.98 (1.26–8.46) vs. 4.55 (1.34–9.25), p = 0.9]. Comparison of patients with IFX-TLs ≥15 μg/ml with those with those with IFX-TLs <15 μg/ml showed not significant difference in the prevalence of the total AEs (66.7% vs. 73.3%, p = 0.77) as well as in the by group analysis (all p > 0.05).

Conclusion

IFX-TLs are not significantly associated with the development of AEs in IBD patients under maintenance treatment with IFX. Further prospective investigation into larger populations is needed to make safe conclusions.