Looking beyond mucosal healing: effect of biologic therapy on transmural healing in pediatric Crohn's disease

Crohn's disease is a chronic inflammatory disease characterized by a progressive transmural bowel damage leading to complications. Anti-TNFα therapy is effective in achieving mucosal healing (MH), but its efficacy on transmural inflammation has been poorly investigated. The aim of this study is to evaluate, in pediatric Crohn's disease, the efficacy of anti-tumor necrosis factor α agents in inducing transmural healing (TH) as assessed by ultrasonography (US). METHODS: Children with Crohn's disease requiring anti-tumor necrosis factor α therapy were prospectively enrolled. Clinical activity, laboratory tests, endoscopic activity, and transmural disease assessed by small intestine contrast US (SICUS) were evaluated at baseline (T0) and then after 9 to 12 months of therapy (T1). We evaluated US quantitative and qualitative parameters: disease extension (centimeters), bowel wall (BW) thickness >3 mm, BW vascularity and stratification strictures, and prestenotic dilatation. TH was defined as a BW thickness <3 mm and normalization of all US parameters at T1. RESULTS: Thirty-two patients were included. Patients with mucosal healing (MH) showed a significant decrease of BW thickness and disease extension at T1 (4.3 ± 1.4 mm and 8 ± 6.3 cm versus 6.1 ± 2.3 mm and 13 ± 5 cm at baseline, respectively) (P < 0.001). Increased vascularity of the BW was found in 80% of patients at T0 and in 18% at T1 (P < 0.001). These parameters did not change in patients without MH, despite clinical and laboratory remission. The presence of stenosis and prestenotic dilatation did not modify in any group. A complete TH was achieved in 14% of patients, all of them showing complete MH. CONCLUSIONS: Biologics induce clinical and laboratory remission and MH in pediatric CD. Although caution is needed due to the small sample size, our data suggest that transmural inflammation also improves during therapy, but a complete TH is achieved only in a small percentage of patients.