title: The high prevalence of knee osteoarthritis in a rural Chinese population: the Wuchuan osteoarthritis study.
abstract: OBJECTIVE
  To estimate the prevalence of radiographic and symptomatic knee osteoarthritis (OA) in a remote rural region of northern China, and compare them with those reported in Beijing and with data from the Framingham (Massachusetts) cohort.
  
  
  METHODS
  A population-based cross-sectional survey was conducted among 1,030 residents of Wuchuan County, Inner Mongolia, age > or =50 years. Survey participants, mostly farmers reporting heavy physical occupational activity, completed an interviewer-based questionnaire, and bilateral weight-bearing posteroanterior semiflexed knee radiographs were obtained.
  
  
  RESULTS
  Whereas the overall prevalence of radiographic knee OA was similar to that demonstrated in the Beijing OA study, men in Wuchuan had approximately double the prevalence of severe radiographic knee OA (prevalence ratio [PR] 2.5, 95% confidence interval [95% CI] 1.6-3.8) and symptomatic knee OA (PR 1.9, 95% CI 1.3-2.9). Women in Wuchuan also had a higher prevalence of both severe radiographic (PR 1.4, 95% CI 1.0-2.0) and symptomatic knee OA (PR 1.6, 95% CI 1.2-2.1) compared with their Beijing counterparts. The prevalence of bilateral OA and lateral compartment disease were 2-3 times higher in both Chinese cohorts compared with estimates from the Framingham OA study.
  
  
  CONCLUSIONS
  The prevalence of symptomatic knee OA in rural areas of China is much higher than reported from urban regions of China or in the Framingham cohort. The higher representation of bilateral and lateral compartment disease in China suggests a unique phenotype to OA. These findings will be useful for guiding the distribution of future health care resources and preventive strategies.
authors.affiliation: People's Hospital, Peking University, Beijing, China.
authors.forename: Xiaozheng
authors.initials: X
authors.lastname: Kang
authors.forename: Marlene
authors.initials: M
authors.lastname: Fransen
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hu
authors.initials: H
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Ke
authors.forename: Ming
authors.initials: M
authors.lastname: Lu
authors.forename: Steve
authors.initials: S
authors.lastname: Su
authors.forename: Xiongying
authors.initials: X
authors.lastname: Song
authors.forename: Yong
authors.initials: Y
authors.lastname: Guo
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Jingbo
authors.initials: J
authors.lastname: Niu
authors.forename: David
authors.initials: D
authors.lastname: Felson
authors.forename: Jianhao
authors.initials: J
authors.lastname: Lin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000208:ethnology*; D015995:Prevalence; D011859:Radiography; D012424:Rural Population / Q000706:statistics & numerical data*; D014505:Urban Population / Q000706:statistics & numerical data