Assessment of skinfold thickness equations in estimating body composition in children with inflammatory bowel

Introduction: Growth is a central process in paediatrics. Weight and height evaluation are therefore routine exams for every child but in some situation, particularly inflammatory bowel disease (IBD), a wider evaluation of nutritional status needs to be performed. The assessment of body composition is essential in order to maintain acceptable growth using the following techniques: Dual-energy X-ray absorptiometry (DEXA), bio-impedance-analysis (BIA) and anthropometric measurements (skinfold thickness skin), the latter being most easily available and most cost effective.

Objectives: To assess the accuracy of skinfold equations in estimating percentage body fat (%BF) in children with inflammatory bowel disease (IBD), compared with assessment of body fat dual energy X-ray absorptiometry (DEXA).

Methods: Twenty-one patients (11 females, 10 males; mean age: 14.3 years, range 12 – 16 years) with IBD (Crohn's disease n = 15, ulcerative colitis n = 6)). Estimated%BF was computed using 6 established equations based on the triceps, biceps, subscapular and suprailiac skinfolds (Deurenberg, Weststrate, Slaughter, Durnin & Rahaman, Johnston, Brook) and compared to DEXA. Concordance analysis was performed using Lin's concordance correlation and the Bland-Altman limits of agreement method.

Results: Durnin & Rahaman's equation shows a higher Lin's concordance coefficient with a small difference amongst raw values for skinfolds and DEXA compared to the other equations. Correlation coefficient between mean and difference is close to zero with a non-significant Bradley-Blackwood test.

Table 1

§ between difference and mean. CI, confidence interval; SD, standard deviation of the difference. ***, p < 0.001
	Spearman	Lin's concordance		Bland-Altman limits of agreement			Bradley-Blackwood
	correlation	Coefficient	95% CI	Difference	SD	Correlation §	Test	P-value
Deurenberg	0.852 ***	0.702	0.512 – 0.891	–3.6	4.2	–0.343	9.84	< 0.001
Weststrate	0.898 ***	0.850	0.734 – 0.966	2.5	3.3	0.003	5.62	< 0.05
Slaughter	0.906 ***	0.848	0.744 – 0.952	0.003	4.9	0.570	4.57	< 0.05
Durnin & Rahaman	0.915 ***	0.871	0.764 – 0.979	–1.0	3.6	–0.033	0.80	0.46
Johnson	0.919 ***	0.810	0.676 – 0.945	–3.4	3.3	–0.040	10.5	< 0.001
Brook	0.900 ***	0.876	0.779 – 0.972	1.8	3.6	0.355	4.18	< 0.05

Conclusion: Body composition in paediatric IBD patients using the Durnin & Rahaman skinfold-equation adequately reflects values obtained by DEXA.

Disclosure of Interest: None Declared