title: Incidence of primary sclerosing cholangitis: a systematic review and meta-analysis.
abstract: Incidence studies of primary sclerosing cholangitis (PSC) are important for describing the disease's burden and for shedding light on the disease's etiology. The purposes of this study were to conduct a systematic review of the incidence studies of PSC with a meta-analysis and to investigate possible geographic variations and temporal trends in the incidence of the disease. A systematic literature search of MEDLINE (1950-2010) and Embase (1980-2010) was conducted to identify studies investigating the incidence of PSC. The incidence of PSC was summarized with an incidence rate (IR) and 95% confidence intervals. The test of heterogeneity was performed with the Q statistic. Secondary variables extracted from the articles included the following: the method of case ascertainment, the country, the time period, the age, the male/female incidence rate ratio (IRR), and the incidence of PSC subtypes (small-duct or large-duct PSC and inflammatory bowel disease). Stratified and sensitivity analyses were performed to explore heterogeneity between studies and to assess effects of study quality. Time trends were used to explore differences in the incidence across time. The search retrieved 1669 potentially eligible citations; 8 studies met the inclusion criteria. According to a random-effects model, the pooled IR was 0.77 (0.45-1.09) per 100,000 person-years. However, significant heterogeneity was observed between studies (P < 0.001). Sensitivity analyses excluding non-population-based studies increased the overall IR to 1.00 (0.82-1.17) and eliminated the heterogeneity between studies (P = 0.08). The IRR for males versus females was 1.70 (1.34-2.07), and the median age was 41 years (35-47 years). All studies investigating time trends reported an overall increase in the incidence of PSC.
  
  
  CONCLUSIONS
  The incidence of PSC is similar in North American and European countries and continues to increase over time. Incidence data from developing countries are lacking, and this limits our understanding of the global incidence of PSC.
authors.affiliation: University of Calgary, Calgary, Alberta, Canada.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Molodecky
authors.forename: Hashim
authors.initials: H
authors.lastname: Kareemi
authors.forename: Rohan
authors.initials: R
authors.lastname: Parab
authors.forename: Herman W
authors.initials: HW
authors.lastname: Barkema
authors.forename: Hude
authors.initials: H
authors.lastname: Quan
authors.forename: Robert P
authors.initials: RP
authors.lastname: Myers
authors.forename: Gilaad G
authors.initials: GG
authors.lastname: Kaplan
mesh_terms: D015209:Cholangitis, Sclerosing / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male