title: Epidemiology of functional constipation and comparison with constipation-predominant irritable bowel syndrome: the Systematic Investigation of Gastrointestinal Diseases in China (SILC).
abstract: BACKGROUND
  The epidemiology and effects of functional constipation (FC) on Chinese people remain unclear.
  
  
  OBJECTIVE
  To investigate the epidemiology of FC and its distinction from constipation-predominant irritable bowel syndrome (IBS-C) in China.
  
  
  METHODS
  A cross-sectional survey was conducted in a representative adult Chinese population (n = 16,078), which was selected from five regions using randomised, stratified, multistage sampling methodology. All respondents completed the modified Rome II questionnaire; 20% were asked to complete the 36-item Short Form (SF-36) and the Epworth Sleepiness Scale (ESS).
  
  
  RESULTS
  Overall, 948 respondents (6%) had FC and FC was more prevalent in women than in men (8% vs. 4%, P < 0.001). Straining and hard stools were the two most frequent symptoms. FC was associated significantly with dyspepsia and abdominal bloating. All SF-36 domain scores were lower for respondents with FC than for those without. The prevalence of clinically meaningful daytime sleepiness was significantly higher in respondents with FC than in those without (22% vs. 14%, P = 0.003). Respondents with FC were more likely to strain, but less likely to have a feeling of incomplete emptying after a bowel movement than those with IBS-C. Respondents with IBS-C experienced similar demographics, quality of life and daytime sleepiness to those with FC.
  
  
  CONCLUSIONS
  The prevalence of FC in China is substantially lower than that in Western countries. FC has negative effects on quality of life and daytime sleepiness. The demographics and burden of illness are similar between FC and IBS-C, although the clinical symptoms are somewhat different.
authors.affiliation: Department of Health Statistics, Second Military Medical University, Shanghai, China.
authors.forename: Y-F
authors.initials: YF
authors.lastname: Zhao
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Ma
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.forename: X-Y
authors.initials: XY
authors.lastname: Yan
authors.forename: Z-S
authors.initials: ZS
authors.lastname: Li
authors.forename: D-W
authors.initials: DW
authors.lastname: Zou
authors.forename: J
authors.initials: J
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003248:Constipation / Q000453:epidemiology* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D003672:Defecation / Q000502:physiology; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012423:Rural Health / Q000706:statistics & numerical data; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D014504:Urban Health / Q000706:statistics & numerical data; D055815:Young Adult