Prevalence and incidence rates of Crohn's disease in mainland China: a meta-analysis of 55 years of research.

Objectives: To better understand the occurrence of Crohn's disease in mainland China and to give an updated overview of the current status of the disease.

Methods: We previously performed a computer-based literature search using 50 years of records from the Chinese Database of Biology and Medicine (1979 to 2002), combined with a manual year-by-year search of the literature from 1950 to 1978. Using a similar method, descriptive epidemiological data of the last 5 years (2003 to September 2007) were collected, pooled with our previous data and re-analyzed.

Results: In total, 3618 cases of Crohn's disease since 1950 have been reported from 29 provinces and cities in mainland China, comprising 2112 male and 1506 female patients, with a male predominance of 1.40:1. More than 75 percent of the patients were aged from 20 to 50 years old, with a mean age of 36.9 +/- 4.4 (1- 84) years. The extrapolated disease incidence and prevalence rates are 0.848/10(5) and 2.29/10(5) person/year, respectively.

Conclusion: The incidence and prevalence rates of Crohn's disease have been increasing rapidly, and the disease is no longer uncommon in China, but these rates are still lower than those in developed countries and other Asian countries. An underestimation may occur because patients who were misdiagnosed or did not seek medical advice could not be included in the study. A future population-based survey is warranted.