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* = Presenting author

P518 Aberrant adipose tissue partitioning with abdominal obesity, defined by MRI, is a hallmark of paediatric Crohn’s disease

D. Thangarajah*1, K. E. Chapell1, S. Mandalia1, G. Frost2, J. M. Fell3

1Imperial College, Section of Academic Neonatal Medicine, London, United Kingdom, 2Imperial College, Nutrition and Dietetic Research Group, Faculty of Medicine, London, United Kingdom, 3Chelsea and Westminster Hospital NHS Foundation Trust, Department of Paediatric Gastroenterology, London, United Kingdom

Background

Paediatric Crohn’s disease (CD) is associated with alterations in body composition; deficits in fat free mass are well described,1 adipose tissue measures are less well defined. Visceral adipose tissue (VAT) is the adipose compartment most strongly associated with chronic inflammation and further intestinal adipose tissue expansion described as ‘creeping fat’ is well recognised from surgical specimens as a hallmark of CD.

Aims: to measure body composition in paediatric CD, specifically to quantify VAT using magnetic resonance imaging (MRI).

Methods

Children (7–18 years) with CD and healthy children to act as controls, were recruited. Volumes (expressed in litres) of the abdominal compartments VAT, subcutaneous adipose tissue (SCA), and muscle, were quantified from MRI at 2 time points, 10 weeks apart for all subjects. Intrahepatocellular lipid (IHCL), expressed as CH2 water, was determined using Magnetic Resonance Spectrometry. Univariate and linear regression analysis was used to identify factors associated with the dependent variable (compartment volume). All variables found to be significantly associated with the dependent variable (p < 0.2) were used to derive a multivariable linear regression model (significance p ≤ 0.05).

Results

In total, 33 children were recruited (25 CD; 16 males), and 8 controls (5 males), mean age 14.0 ± 2.3 years and 13.4 ± 2.5 years; median BMI z-scores -0.74 (-1.65 to 0.03) and 0.11 (-0.65 to 0.41) respectively, (non-significant differences). No participant with CD was receiving concurrent systemic steroids, or had a history of steroid dependent disease. For all compartment volumes, no significant differences were observed in any of the participants between the volumes at 10 weeks and at baseline. CD was significantly associated with more VAT and SCA when compared with healthy children; after adjusting for sex, weight z score, height z score, and pubertal status. CD had 0.39 l (0.16 to 0.63) more VAT than controls, (p < 0.001) and had 1.82 l [1.36 to 2.45] more SCA than controls (p < 0.001). Abdominal muscle volumes were lower in CD when compared with controls, but not statistically significant. There was no significant difference in IHCL between CD and controls.

Conclusion

For the first time in paediatric CD patients, we show an association with abdominal adipose tissue obesity (VAT and SCA) and a trend towards muscle deficit in the context of normal hepatic lipid and BMI measures. The drivers of this obesity phenotype in children with CD is unknown and may be the result of systemic chronic inflammation. VAT expansion could be driven by local intestinal inflammation, the more pronounced SCA expansion that we have identified implies mechanisms involving systemic mediators.

References

[1] Thangarajah D, Hyde MJ, Konteti VK, et al. Systematic review: body composition in children with inflammatory bowel disease. Aliment Pharmacol Ther 2015;42(2):1421–57.