P597 Body composition: a biomarker of therapeutic outcome in patients with Crohn’s disease
N. S. Ding*1, 2, G. Malietzis1, P. F. Lung1, W. Yip1, L. Penez1, T. Ganeshanathan1, S. M. Gabe1, 3, J. T. Jenkins4, 5, A. Hart1
1St Mark’s Hospital, IBD, London, United Kingdom, 2Imperial College London, Department of Surgery and Cancer, London, United Kingdom, 3Imperial College, Surgery, London, United Kingdom, 4St Mark’s Hospital, Department of IBD, Colorectal Surgery and Wolfson Unit of Endoscopy, London, United Kingdom, 5Imperial College, Surgery and Cancer, London, United Kingdom
Primary non-response (PNR) and loss of response (LOR) rates remain a major issue with biological therapy for Crohn’s disease (CD). Variation in body composition (BC) in CD patients is an emerging prognostic factor of poor response to treatment. Visceral obesity is characterised by excess of intra-abdominal adipose tissue accumulation while muscle depletion is characterised by a reduced muscle mass (myopenia) and increased infiltration by inter-and intramuscular fat (myosteatosis).
This study aims to evaluate the role of Computer Tomography (CT) defined BC parameters on PNR and LOR to anti-tumour necrosis factor (TNF) therapy for Crohn’s disease. Inclusion criteria were patients commenced on anti-TNF therapy (adalimumab or infliximab) from 2007-June 2014 with a pretreatment CT. PNR was defined by global assessment of lack of improvement within 6 months of starting therapy. LOR was defined as cessation of anti-TNF in relation to clinical deterioration as assessed by their gastroenterologist. CT image analysis Slice-O-Matic V4.3 software (Tomovision, Montreal, Canada) was performed as described previously.1
Total skeletal muscle and visceral adipose tissue (VAT) surface area (cm2) were evaluated on a single image at the third lumbar vertebrae (L3). The sum of skeletal areas and VAT were normalised for stature (m2). Muscle Attenuation [MA] was reported for the whole muscle area at the third lumbar vertebra level. Reduced skeletal muscle index (myopenia) and low MA (myosteatosis) were defined using the sex-specific lower quartile as the cut-off value. Increased VAT index (visceral obesity) was calculated by using the sex-specific upper quartile.
In total, 106 patients with 47 (44%) male and median age of 44 years had PNR in 26 (24%). Secondary LOR was identified in 29 (27%). According to body mass index (BMI), 13 (12%) were obese. However, of these, 77% did not have visceral obesity. Myopenic patients were more likely to have PNR (OR 4.73 95% [1.81–12.39] p = 0.002) on multivariate analysis. In patients with PNR, 15 (45%) were myopenic. No other factors were associated with LOR or PNR.
Table 1 The relationship between PNR and clinico-pathological parameters
For patients with CD, certain BC profiles may demonstrate predictive effect on treatment responses. Myopenia is associated with primary non-response to anti-TNF therapy. Muscle depletion is a common feature of all chronic pathologies and may represent a modifiable risk factor in Crohn’s patients. Early optimisation of patients undergoing anti-TNF treatments may improve treatment responses.
 Prado CM et al., (2008), Lancet Oncology