P310 Intestinal ultrasound as a tool to assess treatment response in patients with Inflammatory Bowel Diseases

Abstract Background The assessment of treatment response in patients with Inflammatory Bowel Disease (IBD) is often based on clinical indices [Harvey Bradshaw index (HBI), Partial Mayo score (PMS)] and biomarkers [C - reactive protein (CRP)]. Intestinal ultrasound (IUS) has been proposed as a modality capable of objectively evaluating therapeutic response. We investigated the utility of the IUS as a tool to assess treatment response, as well as its association with HBI, PMS and CRP. Methods We included patients with an established diagnosis of IBD who initiated biologic agent (infliximab, adalimumab, ustekinumab, vedolizumab) or tofacitinib. Active disease on IUS was defined as an increase in bowel wall thickness (BWT) >3 mm in the most affected bowel segment, while the presence of a Doppler signal (CDS) in the bowel wall was also assessed. Treatment response on IUS was defined according to the International Bowel Ultrasound Group (IBUS) criteria: reduction in bowel wall thickness (in continuous measurements) >25% or >2.0 mm or >1.0 mm with concomitant reduction in CDS by 1 unit at week 14 ± 2 from the initiation of treatment. Results A total of 19 patients (11 men, 11 with Crohn's disease) underwent IUS at week 0 and week 14 ± 2, while CRP, HBI and PMS were calculated at the same time points. We included bio-naïve as well bio experienced patients (table 1). At week 0, 84.2% of patients exhibited clinical activity (HBI ≥5, PMS ≥2), median CRP was 24.7 mg /L (IQR 18.6-42.8) and median BWT was 7.1mm (IQR 6.5-7.6). At week 14 ± 2, 42.1% of patients remained clinically active, median CRP was 6.8 mg/L (IQR 4.6-20.7) and median BWT was 5.2 mm (IQR 4.6- 6.4). Overall 10/19 patients fulfilled the criteria of treatment response on IUS at week 14 ± 2. Clinical remission was observed in 8/10 patients who demonstrated therapeutic response on IUS and 3/9 patients who did not (p=0.07). Normalization of CRP value (<6mg/L) was observed in 8/10 patients who exhibited treatment response on IUS and in none of the patients who did not (p<0.001). Among the IUS parameters at baseline, a statistically significant difference was found only in the presence of fat wrapping between treatment responders and treatment non-responders (table 2). Finally, median CRP was 4.9 mg/L (IQR 2.6-6.2) in IUS treatment responders and 20.7 mg/L (IQR 10.5-28.5) in IUS treatment non-responders. (p<0.001), with median BWT being 4.7mm (IQR 3.3-5.1) and 6.4mm (IQR 6.1-6.9) respectively (p<0.001). Conclusion IUS represents an objective tool for evaluating treatment response in patients with IBD, which demonstrates a significant correlation with CRP but not with clinical indices of activity.