Prevalence of pediatric Kashin-Beck disease in Tibet

To estimate the prevalence of Kashin-Beck disease (KBD) among children in 2017 in Changdu of Tibet.

We adopted a four-step recruitment to include children aged 7-12 years from seven identified historically endemic counties in Changdu. Posterior-anterior radiographs of right hand and wrist were taken and were graded at four sites (metaphysis, epiphysis, and bony end of phalanges and metacarpal and carpal bones). Two trained researchers independently read the films. Inter-rater reliability was assessed using weighted Kappa and percentage agreement. We fitted logistic regression model to examine the association of age, sex, and altitude of residential village with prevalence of KBD. We examined association between site involvement and severity of KBD using chi-square test.

We recruited 13,573 children (mean age = 9.3 years, 48.40% girls) with a response rate of 95.81%. The overall prevalence of radiographic KBD was 0.26%. Luolong County had the highest prevalence (0.69%), followed by Bianba (0.26%), Basu (0.24%), Mangkang (0.14%), Zuogong (0.14%), Dingqing (0.07%), and Chaya (0.00%). A higher risk of radiographic KBD was associated with older age (P for trend <0.001) and girls (OR=1.86, 95% CI: 0.94, 3.70), but not the altitude of residential village (P for trend=0.957). Metaphysis was involved in all cases of KBD while lesions in epiphysis and bony end of phalanges and metacarpals were only observed in severe cases.

The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu compared with previous census data, suggesting the effectiveness of preventative measures. Key Points • In this study, 13,573 Tibetan children were taken X-ray films of their hands and wrists. • The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu of Tibet. • The preventative measures against KBD launched by Chinese government were effective in decreasing new onsets of KBD among Tibetan children.