title: Epidemiology of lower gastrointestinal bleeding in China: single-center series and systematic analysis of Chinese literature with 53,951 patients.
abstract: OBJECTIVE
  The epidemiology of lower gastrointestinal bleeding (LGIB) in Western populations has been reported; however, there are scant Asian reports. The aim of the present study was to determine the etiology of LGIB in a Chinese population by reporting a retrospective case series and a systematic analysis of Chinese literature.
  
  
  METHODS
  A large colonoscopy database in a tertiary endoscopic center was searched to identify all patients with the indication of LGIB. The data, including patients' sex, age, endoscopic and pathological findings, were collected and analyzed. A comprehensive database search of the Chinese literature was carried out to obtain all relevant studies.
  
  
  RESULTS
  In our series, a total of 720 patients with LGIB were included. There were 425 males and 295 females with a median age of 50 years, the most common etiologies of LGIB were inflammatory bowel disease (IBD; 30.2%), polyps (23.4%) and cancer (10.7%). In 30.2% of all the patients, no obvious causes were identified. A systematic analysis of Chinese literature found an additional 160 studies providing relevant data in 53,951 patients. Overall, colorectal cancer (24.4%), colorectal polyps (24.1%), colitis (16.8%), anorectal disease (9.8%) and IBD (9.5%) were the most common etiologies of LGIB. The main etiologies were different between adults, the elderly and children.
  
  
  CONCLUSIONS
  The study shows colorectal cancer, colorectal polyps, colitis, anorectal disease and IBD were the most common etiologies of LGIB in the Chinese adult and elderly population, whereas colorectal polyps, chronic colitis and intussusception were the main causes of LGIB in Chinese children. Whereas diverticulum, the most common cause of LGIB in Western populations, is uncommon in China.
authors.affiliation: Digestive Endoscopy Center, Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Bai
authors.forename: Jun
authors.initials: J
authors.lastname: Peng
authors.forename: Jun
authors.initials: J
authors.lastname: Gao
authors.forename: Duo-Wu
authors.initials: DW
authors.lastname: Zou
authors.forename: Zhao-Shen
authors.initials: ZS
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D016009:Chi-Square Distribution; D002681:China / Q000453:epidemiology; D003113:Colonoscopy; D005260:Female; D005767:Gastrointestinal Diseases / Q000150:complications / Q000175:diagnosis / Q000208:ethnology*; D006471:Gastrointestinal Hemorrhage / Q000175:diagnosis / Q000208:ethnology* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult