P141 IBUS-SAS for Crohn’s disease ultrasound activity: initial validation and research of the optimal cut-off score
Dragoni, G.(1,2,3);Innocenti, T.(1,2);Lynch, E.N.(1,2);Fiorini, C.(1,2);Parisio, L.(1,2);Roselli, J.(1,2);Bagnoli, S.(2);Macrì, G.(2);Rogai, F.(2);Milani, S.(1);Galli, A.(1);Milla, M.(2);
(1)University of Florence, Department of Experimental and Clinical Biomedical Sciences "Mario Serio”, Florence, Italy;(2)Azienda Ospedaliero Universitaria Careggi, IBD Referral Centre, Florence, Italy;(3)University of Siena, Department of Medical Biotechnologies, Siena, Italy
Background
Intestinal ultrasound (IUS) is being widely accepted as a reliable tool to objectively monitor Crohn’s disease (CD) activity. Recently, an international panel of experts developed an IUS score, called IBUS-SAS (International Bowel Ultrasound Segmental Activity Score). Our aim was to validate this index in a real-life cohort and find a cut-off score that correlates with common lab results of intestinal inflammation.
Methods
All CD patients referred to our unit for IUS examination between November 2020 and February 2021 were scored with the IBUS-SAS. Clinical activity at the time of presentation using Harvey-Bradshaw Index (HBI) was recorded, with remission defined as HBI<5. Faecal calprotectin (FC) and C-reactive protein (CRP) within 8 weeks from IUS were also included. Upper limits of normal for CRP and FC were set at 0.5 mg/dL and 150 µg/g, respectively. Combined biomarkers remission (CBR) was defined as both negative CRP and FC. Pearson’s correlation (rho = ρ) was performed between IBUS-SAS and the other parameters. ROC analyses were carried out to find a predictive cut-off value of IBUS-SAS for CBR.
Results
In total, 40 CD patients were included. The characteristics of the cohort are reported in Table 1. In patients in clinical remission, IBUS-SAS was 27.52±17.42 (mean ±SD); in patients with clinical activity, it was 59.23±22.36. In individuals with negative FC, IBUS-SAS mean value was 26.59±16.85; in case of FC >150 µg/g, it was 50.13±22.16. IBUS-SAS score directly correlated with all parameters considered: clinical activity (ρ=0.38, P=0.01), CRP (ρ=0.33, P=0.04) and FC (ρ=0.42, P=0.007). ROC analysis of IBUS-SAS for CBR revealed an area under the curve of 0.92 (95% CI 0.86-0.97), with a sensitivity of 83.3% and a specificity of 91.3% for a cut-off value of 42.9.
Conclusion
This pilot analysis of IBUS-SAS confirmed its potential to precisely define CD activity, correlating both with clinical scores and biomarkers. An IBUS-SAS cut-off value of 42.9 has demonstrated the highest sensitivity and specificity in predicting normal values of both CRP and FC. A comparison of IBUS-SAS with endoscopic activity and a larger cohort are needed to confirm these findings.