The incidence of inflammatory bowel disease in Northern China: a prospective population-based study

Abstract

Aims & backgrounds: Although inflammatory bowel diseases (IBD) are emerging and increasing in China, epidemiologic data are rarely available. This study was to investigate the epidemiological and clinical characteristics of IBD in Northern China.

Methods: This is a prospective, population-based study of incidence of IBD in Daqing, Heilongjiang province of Northern China from March 1, 2012 to February 28, 2013. All incident patients with IBD were clinically identified by IBD specialist group from five main General Hospitals covering the healthcare service for 1,343,364 residents in the urban areas of Daqing. IBD cases included in this study were followed-up for three months for diagnosis confirmation.

Results: A total of 27 new IBD cases including 25 cases of ulcerative colitis (UC) and 2 cases of Crohn's disease (CD) were identified. The population at risk was 1,343,364 person years. Age-adjusted incidence for total IBD, CD and UC were 1.77, 0.13, and 1.64 per 100,000 population, respectively. A male predominance was found in CD patients (male to female ratio was 2 ∶ 0). In contrast, no obvious gender predominance was found in UC patients (male to female ratio was 1 ∶ 1.1). CD patients were diagnosed at an average age of 39.5 years. The main disease phenotypes of UC were distal colitis with a 24% of proctitis and 56% of left-sided colitis. The mean diagnostic age of UC patients was 48.9 years.

Conclusions: This is the first report on the incidence of IBD in the Northern Chinese population. A lower incidence of IBD, similar male predominance for CD, similar disease phenotype of UC, and lower disease activity was observed in Daqing compared to that in Southern China.

Figure 1. The flow chart of case capture.

The flow chart described the procedure of case capture. Firstly, any patients with suspected or diagnosed IBD were checked medical history and investigations and then were follow-up for 3 months. Then expert team including IBD specialists and pathology experts determined the diagnosis. Finally, a retrospective search was performed to avoid missing cases.