P267 Prospective validation of the IBD - Distribution, Chronicity, Activity (DCA) histological score for Ulcerative Colitis and correlation with UCEIS and MES

Abstract

Abstract Background Histological assessment is not currently recognised as an independent parameter to guide personalised treatment for patients with ulcerative colitis (UC). The development of the Inflammatory Bowel Disease – Distribution, Chronicity, Activity (IBD-DCA) score allows a pragmatic approach to quantitatively evaluate mucosal injury and healing in UC, compared with other pre-existing histological scores (Lang-Schwarz et al., J Crohns Colitis, 2021). This scoring system facilitates a template-based reporting to produce consistent reports with information representing UC severity. Each domain of the IBD-DCA is scored as one of 0 (normal), 1 (mild), or 2 (moderate to severe) based on the presence of established histological UC findings (Figure 1). This project aims to prospectively validate the IBD-DCA score for routine clinical deployment and correlate with endoscopic scores – UC Endoscopic Index of Severity (UCEIS) and Mayo Endoscopic Score (MES). Methods Colonoscopic biopsies from patients with a previously confirmed diagnosis of UC attending one of four hospitals in a single healthcare group from August 2022 to January 2023 were reported using the IBD-DCA histological score, and the corresponding, clinician-reported UCEIS and MES scores were recorded. The histopathology reports were assessed based on the completeness of information in their respective D, C, and A domains. The proportion of reports with information fully represented by the IBD-DCA reporting template and the distribution of biopsy sites were described. The correlation between IBD-DCA with UCEIS and MES was quantified via Kendall’s tau (τ) using the R statistical package v4.3.2. Results Of the 151 cases reported, 70 (46.4%) patients were female and 81 (53.6%) were male. 12 patients (7.9%) had full colonic biopsies, while the remaining cases were assessed with selective biopsies. Rectal biopsy was most often performed (83.4%). The IBD-DCA components were reported for every biopsied sites in 133 (88.1%) cases. Notable correlations included UCEIS vascular pattern with histological chronicity (τ = 0.3891), UCEIS erosions/ulceration with histological activity (τ = 0.3252), and histological activity with the total UCEIS score (τ = 0.3450). MES showed the strongest correlation with histological disease distribution (τ = 0.3450)(Table 1). All p-values < 0.001. Conclusion These data show encouraging uptake of this simple histological reporting template in UC in daily routine use. The findings suggest that the IBD-DCA score may be a useful addition in the clinical management in patients with UC.