Background and aims Ulcerative colitis (UC) associated with primary sclerosing cholangitis (PSC) is usually clinically mild. The aim of the study was to assess whether there is an association between severity of PSC and activity of UC, comparing the course of UC in patients with PSC not needing liver transplantation (LT) and those eventually transplanted.

Methods Between 1990 and 2009, 96 consecutive patients with PSC/UC were seen in the authors' institution. Data were evaluated from a database regarding UC activity (median follow-up 144 months). Follow-up was censored at time of LT or last clinical review.

Results Patients with PSC/UC were divided into two groups: 46 did not need LT (no-LT) and 50 were transplanted (LT). There were no significant differences concerning duration of UC or PSC and extent of UC. The LT group had significantly (p=0.002) more clinically quiescent UC compared with the no-LT group. The LT group had fewer UC flare-ups (p=0.04) and required fewer steroid courses (p=0.025) with shorter duration (p=0.022) and less use of azathioprine (p=0.003). There was an increased need for surgery in the no-LT group (p=0.006). Colon carcinoma and high grade dysplasia were more frequent in the no-LT group (p=0.004). The no-LT group had increased inflammation in the colonic mucosa at histology (p=0.011), but without visual difference at colonoscopy.

Conclusions Clinically progressive PSC requiring LT is associated with a milder course of UC (reduced disease activity and less use of steroids, azathioprine and surgery). This is paralleled by less histological activity and reduced incidence of dysplasia and colon carcinoma.