Colectomy in patients with ulcerative colitis is not associated to future diagnosis of primary sclerosing cholangitis

Background: Primary Sclerosing Cholangitis (PSC) is a hepatobiliary disease closely related to ulcerative colitis (UC). In PSC patients, colectomy has been linked to improved prognosis, especially following liver transplantation. This suggests an involvement of the gut-liver axis in PSC etiology. Objective: We aimed to investigate the association between colectomy and the risk of future PSC in an epidemiological setting. Method: Through nationwide registers, we identified all adults diagnosed with UC in Sweden 1990–2018 and retrieved information on PSC diagnosis and colectomy. Within the UC cohort (n = 61,993 patients), we matched 5577 patients with colectomy to 15,078 without colectomy. Matching criteria were sex, age at UC onset (±5 years), year of UC onset (±3 years), and proctitis at the time of colectomy. Incidence rates of PSC per 1000-person year were calculated, and the Cox proportional hazard regression model estimated hazard ratios (HRs) for PSC until 31 December 2019. Results: During the follow-up, 190 (3.4%) colectomized UC patients and 450 (3.0%) UC comparators developed PSC, yielding incidence rates of 2.6 and 2.4 per 1000 person-years (HR 1.07 [95% CI 0.90–1.28]). The cumulative incidence of colectomy decreased remarkably over calendar periods, but the cumulative incidence of PSC remained unchanged. The risk of developing PSC in colectomized versus comparators changed over time (HR 0.68 [95% CI; 0.48–0.96] in 1990-97 and HR 2.10 [95% CI; 1.37–3.24] in 2011-18). Conclusions: In UC patients, colectomy was not associated with a decreased risk of subsequent PSC. The observed differences in the risk of PSC development over calendar periods are likely due to changes in PSC-diagnosis and UC-treatment.