Early improvement in bowel wall thickness on transperineal ultrasonography predicts treatment success in active ulcerative colitis

Background: Bowel ultrasonography is a non-invasive imaging tool that can repeatedly monitor ulcerative colitis (UC) activity. Aim: This study aimed to determine whether early transabdominal or transperineal ultrasonography changes can predict subsequent clinical response to induction therapy in patients with UC. Methods: This single-centre prospective study explored ultrasonographic predictors for clinical remission (patient-reported outcome-2 ≤ 1 with no rectal bleeding subscore) at week 8 in patients with active UC who underwent induction therapy, in comparison with faecal calprotectin and C-reactive protein (measured at baseline, week 1 and week 8). Predictive factors were assessed using multivariable regression models and receiver-operating-characteristic curve analysis. Results: A total of 100 patients were analysed, of which 54 achieved remission at week 8. Baseline biomarker and ultrasonographic-parameter values were not predictive of remission. Contrastingly, change from baseline to week 1 in rectal bowel wall thickness measured using transperineal ultrasonography was an independent predictor of remission by week 8 (adjusted odds ratio is associated with a 1-mm decrease: 1.90 [95% confidence interval, 1.22–2.95]). In a subgroup analysis of the patients who did not achieve remission in 1 week, the predictive value of change in rectal bowel wall thickness remained high (AUC = 0.77 [95% confidence interval, 0.61–0.88]). Conclusion: Improvement in rectal bowel wall thickness measured using transperineal ultrasonography at week 1 predicts treatment success and potentially facilitates decision making during the early course of induction therapy in UC.