P526 Body mass index and response to TNF-α inhibitors in inflammatory bowel disease

Background

Obesity is an emerging issue in the care of patients with inflammatory bowel disease (IBD). The aim of the study was to evaluate whether the response to TNF-α inhibitors (infliximab and adalimumab) could be influenced by body mass index (BMI) in IBD. Unlike adalimumab (ADA), a recombinant humanised IgG antibody against (TNF-α), the dosing of infliximab (IFX); a monoclonal chimeric antibody is weight-based.

Methods

We identified a cohort of patients with IBD at a single centre, naïve to biologic therapy and stratified them according to their weight and BMI. The primary outcome is the first occurrence of loss of response defined as clinical deterioration requiring hospitalisation, surgery, corticosteroid use, dose escalation or discontinuation of therapy and/or evidence of activity on endoscopy. Patients were followed up for 4 years. Multivariate analysis with logistic regression were used to compare variables.

Results

There was a total of 104 IBD patients; 51% (n = 53) were males and the median age was 40 years (19–76 years). The majority (n = 89; 85.6 %) had Crohn’s disease and the rest (n = 15; 14.4%) were diagnosed with ulcerative colitis. The median BMI was 24.5 kg/m² (13.4–41.5 kg/m²). Patients had been diagnosed with IBD for a total median duration of 13 years (1–50 years). The majority of patients were not active smokers (n = 92; 88.5%) with the rest being current smokers (n = 12; 11.5%). Of the 104 patients, there were an equal number of patients in the IFX (n = 52) and ADA (n = 52) groups. There were no differences in the demographics, types of disease and BMI distribution in the two groups.

In terms of loss of response, type of drug (IFX/ADA) was not found to be a significant risk factor (p = 0.250) along with the type of IBD (p = 0.420), age (p = 0.612) and gender (p = 0.600). However, the duration of disease was a significant factor (p = 0.026). There was a trend of accelerated time to loss of response for patients with BMI ≥30 kg/m², in ADA group, but not significant (p = 0.314) compared with IFX of the same BMI group (Figure 1). For BMI <30 kg/m² in both groups, there was no difference in time to loss of response (p = 0.259). However, patients on ADA with BMI ≥30 kg/m² had a significant loss of response compared with patients on IFX with BMI <30 kg/m² (adjusted HR 5.6; p = 0.038).