Changes in anthropometric parameters and body composition in a pediatric IBD population treated with anti-TNFα: a prospectivestudy with 4 years follow-up

Introduction: Children affected by inflammatory bowel disease (PIBD) have decreased fat-free mass (FFM) compared to healthy controls. Moreover, anti-TNFα treatment can cause body mass index (BMI) and fat mass (FM) increase. We aim to prospectively evaluate modification of anthropometric parameters and body composition in PIBD patients during anti-TNFα therapy Methods: IBD children (6-18 years) anti-TNFα naïve were prospectively enrolled from 05/2020 to 01/2024 in a single tertiary centre. Anthropometric parameters (body weight-BW, height, BMI) and body composition (FM%, FFM%) with bioelectrical impedance analysis were collected at baseline (first anti-TNFα dose) and at 3-6-12- 18-24 months of therapy Results: Overall, 16 PIBD patients were enrolled (14 Crohn’s Disease, 2 ulcerative colitis). • From baseline to 12 months a statistically significant increase of BW (baseline BW-median 43.7 Kg vs 12- months BW-median 53.7 Kg, p=0.05) and BMI (baseline BMI-median 17.6 vs 12- months BMI-median 21.9, p=0.02) was detected. • Height increased but difference did not reach statistical significance (p=0.22). • At 24 months, the increase of BW and BMI persisted with a statistically significant difference from baseline (BMI p=0.002, BW p=0.009). • At 24-months an increase of FM% and a decrease of FFM% was observed although not statistically significant compared to baseline (FM p=0.15; FFM p=0.06). Conclusion: Our prospective study shows an increase of BW, BMI with a tendency towards increased FM and decreased FFM in PIBD during antiTNFα therapy. This effect could be related to gut healing, but also to increased adipogenesis mediated by anti-TNFα drugs. Nutritional follow-up is mandatory for early detection of patients with overweight and increased FM.