The Burden of Large and Small Duct Primary Sclerosing Cholangitis in Adults and Children: A Population-Based Analysis

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Abstract
The epidemiology of primary sclerosing cholangitis (PSC) has been incompletely assessed by population-based studies. We therefore conducted a population-based study to determine: (a) incidence rates of large and small duct PSC in adults and children, (b) the risk of inflammatory bowel disease on developing PSC, and (c) patterns of clinical presentation with the advent of magnetic resonance cholangiopancreatography (MRCP). All residents of the Calgary Health Region diagnosed with PSC between 2000 and 2005 were identified by medical records, endoscopic, diagnostic imaging, and pathology databases. Demographic and clinical information were obtained. Incidence rates were determined and risks associated with PSC were reported as rate ratios (RR) with 95% confidence intervals (CI). Forty-nine PSC patients were identified for an age- and gender-adjusted annual incidence rate of 0.92 cases per 100,000 person-years. The incidence of small duct PSC was 0.15/100,000. In children the incidence rate was 0.23/100,000 compared with 1.11/100,000 in adults. PSC risk was similar in Crohn's disease (CD; RR 220.0, 95% CI 132.4–343.7) and ulcerative colitis (UC; RR 212.4, 95% CI 116.1–356.5). Autoimmune hepatitis overlap was noted in 10% of cases. MRCP diagnosed large duct PSC in one-third of cases. Delay in diagnosis was common (median 8.4 months). A minority had complications at diagnosis: cholangitis (6.1%), pancreatitis (4.1%), and cirrhosis (4.1%). Pediatric cases and small duct PSC are less common than adult large duct PSC. Surprisingly, the risk of developing PSC in UC and CD was similar. Autoimmune hepatitis overlap was noted in a significant minority of cases.