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 โฅ60 years. Participants underwent standard weightโbearing 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 ageโstandardized 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 ageโstandardized prevalence ratio being 0.34 (95% confidence interval [95% CI] 0.20โ0.54) and 0.43 (95% CI 0.31โ0.59) 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 ageโstandardized prevalence ratio being 0.06 (95% CI 0.01โ0.18) in Chinese men and 0.18 (95% CI 0.10โ0.30) in Chinese women. Calcium levels in the tap water in Beijing were 15โfold higher than in Framingham, whereas no difference was found in magnesium and phosphate levels.
Conclusion
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.