P081 Therapeutic Drug Monitoring of infliximab in Crohn’s Disease: Cut-off points during maintenance therapy.

Valdes, T.(1);Vilches Arenas, A.(2);Maldonado Perez, B.(1);Castro Laria, L.(1);Merino Bohorquez, V.(3);Argüelles Arias, F.(1);

(1)University Hospital Virgen Macarena, Gastroenterology Department, Sevilla, Spain;(2)University Hospital Virgen Macarena, Preventive Medicine, Sevilla, Spain;(3)University Hospital Virgen Macarena, Pharmacy Department, Sevilla, Spain;


Therapeutic drug monitoring of infliximab in Crohn's disease is necessary to optimize treatments. However, infliximab serum levels are not well defined.

The aim of the study was to find our cut-off of infliximab serum levels in Crohn’s disease patients in remission in clinical practice. Furthermore, we tried to identify other predictors of long-term benefit of infliximab therapy.


Observational, retrospective and single-center study of patients diagnosed with Crohn's disease on maintenance therapy with infliximab from January 2019 to July 2020.

Infliximab trough levels and antibodies to infliximab were measured at least three times, after 6 months of treatment. The tests were performed using enzyme linked immunosorbent assay. Clinical remission was defined using the Harvey Bradshaw index ≤4. The interpretation of data was by ROC analysis.


105 Crohn's disease patients were included in the study, 57.1% men, with a median age at diagnosis of 26 years. The rest of the characteristics are in table 1.

The best infliximab level cut-off point classifying patients in clinical remission was 4 μg/ml with an area under the curve of 0.801 (figure 1 and 2).

Median infliximab trough levels were significantly higher when patients achieved clinical remission [4.8 (3-8) μg/ml] versus [0.59 (0.1-2.4) μg/ml].

In the multivariate analysis we observed that the variables age, time on infliximab treatment and time of disease evolution were associated with non-remission (table 2).


Infliximab levels are an objective parameter related to clinical remission in maintenance therapy in patients with Crohn's disease. Our cut-off point associated with clinical remission was 4 μg/ml.