THE EVALUATION OF INFLIXIMAB TROUGH LEVEL FAVORS MAINTENANCE THERAPY OF PATIENTS WITH INFLAMMATORY BOWEL DISEASE

Crohn's disease (CD) and ulcerative colitis (UC) are chronic diseases that result from the deregulation of the mucosal immune system of the gastrointestinal tract. The use of biological therapies, including infliximab (IFX), is one of the strategies to treat both CD and UC. The IFX treatment is monitored by complementary tests, namely: fecal calprotectin (FC); C-reactive protein (CRP); and endoscopic and cross-sectional imaging. Besides, serum IFX evaluation and antibody detection are also used.

To evaluate trough levels (TL) and antibodies in a population with inflammatory bowel (IBD) disease undergoing treatment with IFX, and the factors that might impact the treatment effectiveness.

Retrospective, cross-sectional study with patients with IBD that were assessed for TL and antibody (ATI) levels in a southern Brazilian hospital, from June 2014 to July 2016.

The study assessed 55 patients (52.7% female) submitted to serum IFX and antibody evaluations (95 blood samples, 55 first test; 30 second test, and 10 as third testing. Forty-five (47.3%) cases were diagnosed with CD (81.8%), and ten with UC (18.2%). Serum levels were adequate in 30 samples (31.57%), subtherapeutic in 41 (43.15%), and supratherapeutic in 24 (25.26%). IFX dosages were optimized for 40 patients (42.10%), maintained for 31 (32.63%), and discontinued for 7 (7.60%). The intervals between infusions were shortened in 17.85% of the cases. In 55 tests (55.79%), the therapeutic approach was exclusively defined according to IFX and/or serum antibody levels. The assessment of patients one year later indicated that: the approach was maintained with IFX for thirty-eight patients (69.09%); the class of biological agent was changed for eight (14.54%); changes using the same class of biological agent occurred for two patients (3.63%); the medication was discontinued and not replaced for three patients (5.45%), and four patients (7.27%) were lost to follow-up.

There were no differences in TL between groups with or without immunosuppressants, serum albumin (ALB), erythrocyte sedimentation rate (ESR), FC, CRP, and endoscopic and imaging examinations. Current therapeutic approach could be maintained for almost 70% of patients. Thus, serum and antibody levels are a useful tool in the follow-up of patients undergoing maintenance therapy and after treatment induction in patients with inflammatory bowel disease.