Relationship of Body Mass Index to Clinical Outcomes after Infliximab Therapy in Patients with Crohn's Disease

There are conflicting data for the role of obesity in Crohn's disease (CD) and the effect on long-term clinical outcomes is poorly studied. Some evidence suggests obesity is associated with diminished responsiveness to biological agents, especially anti-tumour necrosis factor antibodies. We aimed to examine the influence of body mass index (BMI) on the response to infliximab in CD in a retrospective analysis. The outcomes of interest within 12 months were: (1) Composite loss of response (CD-related flare or surgery; LOR); (2) any CD-related surgery (CDRS); and (3) CD-related intestinal resectional surgery (CDRIS). A total of 388 patients were included. The mean BMI was 24.2kg/m(2) [+/- standard deviation (SD) 5.1]. Of the 388 patients, 137 (35.4%) were overweight (BMI: 25-29.9kg/m(2)) or obese (BMI: a parts per thousand yen30kg/m(2))-160 (41.6%) patients had LOR during the 12 months follow-up; 121 (31.4%) required CDRS, and 109 (28.2%) required CDRIS. Multivariate analysis showed that increasing BMI (per unit, kg/m(2) increase) reduced the risk of LOR [odds ratio (OR): 0.98], CDRS (OR: 0.95), and CDRIS (OR: 0.95). Rates for all outcomes were higher, but not significantly so, in the extreme categories (underweight and obese) and lower in the underweight categories compared with normal BMI. Exclusion of the obese category of patients strengthened this relationship. Body mass index at first infusion of infliximab has a non-linear relationship with outcomes at 12 months. The worst outcomes are at the extremes of weight (underweight and obese categories). Increasing BMI is associated with a modest reduction in risk of LOR, CDRS, and CDRIS within 12 months, increasing with the exclusion of the obese category.