title: Lower prevalence of chondrocalcinosis in Chinese subjects in Beijing than in white subjects in the United States: the Beijing Osteoarthritis Study.
abstract: OBJECTIVE
  Chondrocalcinosis, which can promote joint inflammation and cartilage degeneration, is highly prevalent in elderly white subjects. Data on its prevalence are scarce in other ethnic populations. This study was undertaken to compare the prevalence of chondrocalcinosis in Chinese subjects with that in white subjects.
  
  
  METHODS
  We recruited a random sample of Beijing residents ages >or=60 years. Participants underwent standard weight-bearing anteroposterior knee radiography and posteroanterior hand radiography using the protocols developed in the Framingham Osteoarthritis Study. Radiographic chondrocalcinosis was defined as present in a knee or wrist when there was evidence of definite linear cartilage calcification. We compared the prevalence of chondrocalcinosis in Chinese subjects with that in white subjects using age-standardized prevalence ratios. We used identical methods to collect samples of tap water from 2 cities and measured their levels of calcium, magnesium, and phosphate in the same laboratory.
  
  
  RESULTS
  Chinese subjects had a much lower prevalence of knee chondrocalcinosis (1.8% in men, 2.7% in women) than did white subjects (6.2% in men, 7.7% in women), with the age-standardized prevalence ratio being 0.34 (95% confidence interval [95% CI] 0.20-0.54) and 0.43 (95% CI 0.31-0.59) in men and women, respectively. Wrist chondrocalcinosis was rare in elderly Chinese subjects (prevalence 0.3% in men and 1.0% in women), with the age-standardized prevalence ratio being 0.06 (95% CI 0.01-0.18) in Chinese men and 0.18 (95% CI 0.10-0.30) in Chinese women. Calcium levels in the tap water in Beijing were 15-fold higher than in Framingham, whereas no difference was found in magnesium and phosphate levels.
  
  
  CONCLUSIONS
  Knee chondrocalcinosis and wrist chondrocalcinosis are far less common in Chinese subjects in Beijing than in US white subjects in Framingham, Massachusetts. Given the current lack of understanding of the etiology of chondrocalcinosis, further epidemiologic studies of the impact of genetic and environmental factors on occurrence of chondrocalcinosis are indicated.
authors.affiliation: Boston University Medical Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Robert
authors.initials: R
authors.lastname: Terkeltaub
authors.forename: Michael
authors.initials: M
authors.lastname: Nevitt
authors.forename: Ling
authors.initials: L
authors.lastname: Xu
authors.forename: Tuhina
authors.initials: T
authors.lastname: Neogi
authors.forename: Piaran
authors.initials: P
authors.lastname: Aliabadi
authors.forename: Jingbo
authors.initials: J
authors.lastname: Niu
authors.forename: David T
authors.initials: DT
authors.lastname: Felson
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D002805:Chondrocalcinosis / Q000208:ethnology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000208:ethnology; D015995:Prevalence; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*