Risk of colorectal neoplasia according to histologic disease activity in patients with inflammatory bowel disease and colonic post-inflammatory polyps.

Abstract

While post-inflammatory polyps (PIPs) have historically been a risk factor for colorectal neoplasia (CRN), histologic activity may explain this association. We aimed to assess the impact of histologic activity on CRN occurrence in IBD patients with colonic PIPs. Patients with PIPs on surveillance colonoscopy at Saint-Antoine hospital between 1 January 1996 and 31 December 2020 were included and subsequent colonoscopies were assessed. Histologic IBD activity was assessed by the Nancy histologic index. Survival and Cox regression analysis were performed to assess the strength of the association of PIPs and other patient variables with progression to CRN. A total of 173 patients with at least two surveillance colonoscopies with PIPs at index colonoscopy were compared to a similar group of 252 patients without PIPs. In survival analysis, the presence or PIPs at index colonoscopy did not impact the risk of CRN in patients with histological inflammation (p = 0.83) and in patients without histological inflammation (p = 0.98). The risk of CRN was associated with increasing Nancy index score of 3 or 4 (HR: 4.16; 95% CI 1.50-11.52 and HR: 3.44; 95% CI 1.63-7.24), age (HR per 10-year increase: 1.37; 95% CI 1.13-1.66) and first-degree family history of colorectal cancer (HR: 5.87; v 1.31-26.26), but not PIPs (HR: 1.17; 95% CI 0.63-2.17). After controlling for histologic activity, PIPs do not increase the risk of CRN in IBD patients. Histologic activity rather than PIPs should be considered in the risk assessment of CRN.