[1] Capital Med Univ, Beijing Friendship Hosp, Natl Clin Res Ctr Digest Dis, Beijing, Peoples R China
[2] Peking Univ, Int Hosp, Dept Endocrinol & Metab, Beijing, Peoples R China
[3] Peking Univ, Hlth Sci Ctr, Sch Publ Hlth, Dept Epidemiol & Biostat, Beijing 100191, Peoples R China
[4] Univ Cambridge, Sch Clin Med, Primary Care Unit, Cambridge, England
[5] McMaster Univ, Dept Clin Epidemiol & Biostat, Hamilton, ON, Canada
[6] Peking Univ, Peoples Hosp, Dept Endocrinol & Metab, Beijing, Peoples R China