Factors correlated with transmural healing in patients with Crohn's disease in long-term clinical remission on anti-TNF medication

Background & aims: Transmural healing is a long-term target for patients with Crohn's disease. Factors contributing to its promotion are poorly understood. This study assessed factors correlating with transmural healing based on intestinal ultrasound, in patients in long-term clinical remission on anti-TNF. Methods: 68 consecutive Crohn's patients on adalimumab (50) or infliximab (18) therapy with clinical remission ≥1 year were recruited and assessed for clinical features, trough serum levels of anti-TNF and intestinal ultrasound findings. Univariate analysis and multivariate binary logistic regression analysis identified variables independently associated with bowel wall thickening behavior. Results: Sixty eight patients were in remission for a mean of 4.1 years. Thirty-six patients (52.9 %) showed anti-TNF trough levels below the normal threshold. Twenty-two patients (38.4 %) showed transmural healing, 32 (47.1 %) transmural response, and 26 (38.2 %) no treatment response. Transmural healing correlated with higher BMI and lower baseline bowel wall thickening; transmural response correlated with short Crohn's disease duration, high drug levels, and with non-stricturing phenotype. Treatment non-response correlated with lower BMI, lower drug levels, higher baseline bowel wall thickening, and stricturing phenotype. Conclusions: Lack of transmural healing in stable remission Crohn's patients on anti-TNF therapy is multifactorial, mainly due to low anti-TNFs trough levels, development of strictures, and higher baseline bowel wall thickening at treatment initiation.