Background: Primary sclerosing cholangitis (PSC) is an independent risk factor for colorectal cancer (CRC) in ulcerative colitis (UC) patients (pts), however the reason for this is not known. We hypothesized that patients with UC and concomitant PSC (UC-PSC) may have more active subclinical disease than patients with UC alone.
Methods: This is a retrospective case control study of pts with UC-PSC (cases) and UC without PSC (controls). Included pts had pancolitis and were in clinical remission (defined as Simple Clinical Colitis Activity Index score ≤2) within 3 months of a colonoscopy. Colonoscopy, pathology and clinical data from 2011–2016 were reviewed. Disease activity was scored using a modified Mayo score for 3 segments: right colon, left colon, and rectum. Histologic scores were translated from pathology reports as quiescent, mild, moderate or severe. We dichotomized results to quiescent and active disease, and compared degree of endoscopic and histologic activity by segment between cases and controls using univariate and multivariate generalized estimating equation (GEE) logistic regression models. We also assessed concordance between endoscopic and histologic scores.
Results: 143 patients (23 UC-PSC; 120 UC) with 205 exams (36 UC-PSC; 169 UC) were included. Cases and controls were similar except that cases were younger at first colonoscopy and more often males.
Cases had significantly more endoscopic activity (OR=4.12, 95% CI 1.67–10.20, p=0.002) and more histologic activity (OR=5.13, 95% CI 2.25–11.68, p<0.001) in the right colon compared to controls, which remained significant after adjusting for gender, age at colonoscopy, steroid use and race. Cases also had significantly greater odds of worse histologic vs. endoscopic inflammation of the right colon compared to controls (OR =3.14, 95% CI 1.24–7.97, p=0.02). In contrast, cases had significantly less histologic activity than controls in the rectum on multivariate analysis (OR=0.24, 95% CI 0.08–0.72, p=0.01).
Conclusions: UC patients with PSC in clinical remission have more frequent and severe histologic and endoscopic disease activity of the right colon compared to UC patients without PSC. We believe that these findings provide insight into the increased cancer risk of PSC patients, and warrant more careful right-sided disease activity monitoring in these at-risk patients.